Diversity of finfish species in the Scotia–Fundy region

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Diversity of Finfish Species in the Scotia-Fundy Region

M. Strong and A. Hanke

Biological Station St. Andrews, N. B. EOG 2X0

January 1995

Canadian Technical Report of Fisheries and Aquatic Sciences No. 2017

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141 Fisheries Pêches and Oceans et Océans Canadâ

Canadian Technical Report of Fisheries and Aquatic Sciences 2017

January 1995

Diversity of Finfish Species in the Scotia-Fundy Region

by

Michael Strong and Alex Hanke

Depa rtment of Fisheries and Oceans Biological Station

St. Andrews, New Brunswick EOG 2X0 Canada

This is the two hundred and eighteenth Technical Report of the Biological Station, St. Andrews, N. B.

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© Minister of Supply and Services Canada 1994 Cat. No. Fs 97-612017E ISSN 0706-6457

Correct citation for this publication:

Strong, M., and A. Hanke. 1995. Diversity of finfish species in the Scotia-Fundy Region. Can. Tech. Rep. Fish. Aquat. Sci. 2017: viii + 106 p.

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TABLE OF CONTENTS

Page

Abstract ....................................................................viIntroduction .................................................................1Methods ....................................................................1

Data source ...........................................................1Vessels and sampling gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Fishing protocols . . . . . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Data analysis .......................................................... 1

Results .....................................................................4Data analysis .......................................................... 4General summaries by stratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Discussion ................................................................. 31Effects of sampling intensity and gear performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Factors related to diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Implications for resource management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Conclusions ............................................................ .. 33Acknowledgments ............................................................ 33References ................................................................. 34Tables .................................................................... 35Figures .................................................................... 48

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LIST OF TABLES

Page

Table 1. Summary by stratum of summer survey sampling effort, mean number of species per tow, total number of species observed since 1970, percentage of species determined as long-term residents and mean number of species observed per year since 1984 35

Table 2. Summary of summer survey data by stratum in 4-yr time periods from 1970. (A) number of tows fished, (B) mean number of species per tow, and (C) species reported per time period 36

Table 3. Common and scientific names of species in Scotia-Fundy 37

Table 4. Summary of seasonal survey data from 1979-85. (A) the number of tows fished, (B) the mean number of species per tow, and (C) the number of species reported per season 46

Table 5. Residency status by stratum of species compliment by season. The total number of species observed by stratum from all seasonal surveys, the percentage of species occurring in spring, the percentage of species occurring in summer, the percentage of species occurring in fall, the percentage of species occurring in all seasons 47

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LIST OF FIGURES

Page

Fig. 1. Scotia-Fundy summer survey stratification scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Fig. 2. Offshore banks and basins of the Scotia-Fundy Region . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Fig. 3. Cumulative number of species reported per stratum from summer data for strata 440-445 .. 49Fig. 4. Cumulative number of species reported per stratum from summer data for strata 446-451 .. 49Fig. 5. Cumulative number of species reported per stratum from summer data for strata 452-457 .. 49Fig. 6. Cumulative number of species reported per stratum from summer data for strata 458-463 .. 49Fig. 7. Cumulative number of species reported per stratum from summer data for strata 464-472 .. 50Fig. 8. Cumulative number of species reported per stratum from summer data for strata 473-478 .. 50Fig. 9. Cumulative number of species reported per stratum from summer data for strata 480-485 .. 50Fig. 10. Cumulative number of species reported per stratum from summer data for strata 490-495 . . 50Fig. 11. Sampling effort and effectiveness per stratum from summer data for strata 440-495 ...... 51Fig. 12. Spatial patterns of diversity in summer 1970-73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Fig. 13. Spatial patterns of diversity in summer 1974-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Fig. 14. Spatial patterns of diversity in summer 1978-81 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Fig. 15. Spatial patterns of diversity in summer 1982-85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Fig. 16. Spatial patterns of diversity in summer 1986-89 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Fig. 17. Spatial patterns of diversity in summer 1990-93 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Fig. 18. Trend in mean number of species per tow 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Fig. 19. Species composition of stratum 440 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 56Fig. 20. Species composition of stratum 441 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 56Fig. 21. Species composition of stratum 442 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 57Fig. 22: Species composition of stratum 443 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 57Fig. 23: Species composition of stratum 444 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 58Fig. 24: Species composition of stratum 445 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 58Fig. 25: Species composition of stratum 446 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 59Fig. 26: Species composition of stratum 447 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 59Fig. 27: Species composition of stratum 448 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 60Fig. 28: Species composition of stratum 449 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 60Fig. 29: Species composition of stratum 450 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 61Fig. 30: Species composition of stratum 451 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 61Fig. 31: Species composition of stratum 452 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 62Fig. 32: Species composition of stratum 453 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 62Fig. 33: Species composition of stratum 454 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 63Fig. 34: Species composition of stratum 455 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 63Fig. 35: Species composition of stratum 456 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 64Fig. 36: Species composition of stratum 457 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 64Fig. 37: Species composition of stratum 458 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 65Fig. 38: Species composition of stratum 459 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 65Fig. 39: Species composition of stratum 460 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 66Fig. 40: Species composition of stratum 461 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 66Fig. 41: Species composition of stratum 462 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 67Fig. 42: Species composition of stratum 463 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 67Fig. 43: Species composition of stratum 464 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 68Fig. 44: Species composition of stratum 465 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 68Fig. 45: Species composition of stratum 466 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 69Fig. 46: Species composition of stratum 470 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 69Fig. 47: Species composition of stratum 471 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 70Fig. 48: Species composition of stratum 472 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 70Fig. 49: Species composition of stratum 473 in summer 1970-93 . . . . . . . . . . . . . . . . . . . . . . . . . . 71Fig. 50: Species composition of stratum 474 in summer 1970-85 . . . . . . . . . . . . . . . . . . . . . . . . . . 71

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Figure Legends (cont'd)

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Fig. 51: Species composition of stratum 475 in summer 1970-93 72 Fig. 52: Species composition of stratum 476 in summer 1970-93 72 Fig. 53: Species composition of stratum 477 in summer 1970-93 73 Fig. 54: Species composition of stratum 478 in summer 1970-93 73 Fig. 55: Species composition of stratum 480 in summer 1970-93 74 Fig. 56: Species composition of stratum 481 in summer 1970-93 74 Fig. 57: Species composition of stratum 482 in summer 1970-93 75 Fig. 58: Species composition of stratum 483 in summer 1970-93 75 Fig. 59: Species composition of stratum 484 in summer 1970-93 76 Fig. 60: Species composition of stratum 485 in summer 1970-93 76 Fig. 61: Species composition of stratum 490 in summer 1970-93 77 Fig. 62: Species composition of stratum 491 in summer 1970-93 77 Fig. 63: Species composition of stratum 492 in summer 1970-93 78 Fig. 64: Species composition of stratum 493 in summer 1970-93 78 Fig. 65: Species composition of stratum 494 in summer 1970-93 79 Fig. 66: Species composition of stratum 495 in summer 1970-93 79 Fig. 67: Relative species diversity and inventory by stratum " 80 Fig. 68: Spatial patterns of diversity in spring 1979-85 81 Fig. 69: Spatial patterns of diversity in summer 1979-85 81 Fig. 70: Spatial patterns of diversity in fall 1979-85 81 Fig. 71: Species composition of stratum 440 by season 1979-85 82 Fig. 72: Species composition of stratum 441 by season 1979-85 82 Fig. 73: Species composition of stratum 442 by season 1979-85 83 Fig. 74: Species composition of stratum 443 by season 1979-85 83 Fig. 75: Species composition of stratum 444 by season 1979-85 84 Fig. 76: Species composition of stratum 445 by season 1979-85 84 Fig. 77: Species composition of stratum 446 by season 1979-85 85 Fig. 78: Species composition of stratum 447 by season 1979-85 85 Fig. 79: Species composition of stratum 448 by season 1979-85 86 Fig. 80: Species composition of stratum 449 by season 1979-85 86 Fig. 81: Species composition of stratum 450 by season 1979-85 87 Fig. 82: Species composition of stratum 451 by season 1979-85 87 Fig. 83: Species composition of stratum 452 by season 1979-85 88 Fig. 84: Species composition of stratum 453 by season 1979-85 88 Fig. 85: Species composition of stratum 454 by season 1979-85 89 Fig. 86: Species composition of stratum 455 by season 1979-85 89 Fig. 87: Species composition of stratum 456 by season 1979-85 90 Fig. 88: Species composition of stratum 457 by season 1979-85 90 Fig. 89: Species composition of stratum 458 by season 1979-85 91 Fig. 90: Species composition of stratum 459 by season 1979-85 91 Fig. 91: Species composition of stratum 460 by season 1979-85 92 Fig. 92: Species composition of stratum 461 by season 1979-85 92 Fig. 93: Species composition of stratum 462 by season 1979-85 93 Fig. 94: Species composition of stratum 463 by season 1979-85 93 Fig. 95: Species composition of stratum 464 by season 1979-85 94 Fig. 96: Species composition of stratum 465 by season 1979-85 94 Fig. 97: Species composition of stratum 466 by season 1979-85 95 Fig. 98: Species composition of stratum 470 by season 1979-85 95 Fig. 99: Species composition of stratum 471 by season 1979-85 96 Fig. 100: Species composition of stratum 472 by season 1979-85 96 Fig. 101: Species composition of stratum 473 by season 1979-85 97

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Figure Legends (cont'd)

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Fig. 102: Species composition of stratum 474 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . . 97Fig. 103: Species composition of stratum 475 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . . 98Fig. 104: Species composition of stratum 476 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . . 98Fig. 105: Species composition of stratum 477 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . . 99Fig. 106: Species composition of stratum 478 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . . 99Fig. 107: Species composition of stratum 480 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 100Fig. 108: Species composition of stratum 481 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 100Fig. 109: Species composition of stratum 482 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 101Fig. 110: Species composition of stratum 483 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 101Fig. 111: Species composition of stratum 484 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 102Fig. 112: Species composition of stratum 485 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 102Fig. 113: Species composition of stratum 490 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 103Fig. 114: Species composition of stratum 491 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 103Fig. 115: Species composition of stratum 492 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 104Fig. 116: Species composition of stratum 493 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 104Fig. 117: Species composition of stratum 494 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 105Fig. 118: Species composition of stratum 495 by season 1979-85 . . . . . . . . . . . . . . . . . . . . . . . . 105Fig. 119: Seasonal changes in species diversity and inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

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ABSTRACT


Spatial and temporal trends in the diversity of finfish species were investigated from summer data collected on Scotia-Fundy bottom-trawl research surveys from 1970-93, and from spring and fall data collected from 1979-85.

To reveal time and spatial trends, contour plots of the number of species captured per representative survey set were created. The summer data indicated that the most diverse areas were found to exist in the Bay of Fundy and the in the "Gully" region east of Sable Island. The least diverse areas were found in the La Have Bank area, and in the mid-depth region south of Banquereau Bank. The season of highest diversity for most areas was the fall, while the Bay of Fundy was the highest area.

The relative complexity and dynamics of communities found in offshore regions was summarized by plots of their respective species composition, and the frequencies of occurrence of all species repo rted by time and season. Long-term decreases in the frequencies of occurrence of 26 species were detected in the sumrrter season, the most pronounced cases including smooth skate (Raja senta), thorny skate (Raja radiata), monkfish (Lophius americanus), cusk (Brosme brosme), haddock (Melanogrammus aeglefinus) and wolffish (Anarhichas lupus).

RÉSUMÉ


Les tendances spatiales et temporelles des diverses espèces de poissons ont été étudiées à partir des données recueillies au cours des relevés effectués à l'aide de chaluts de fond dans la région de Scotia-Fundy durant l'été, de 1970 à 1993, et à partir de données recueillies le printemps et l'automne de 1979 à 1985.

Pour découvrir les tendances temporelles et spatiales, on a crée des tracé de contours du nombre d'espèces capturées par trait de chalut représentatif. Les données de l'été indiquaient que les régions les plus diversifiées se trouvaient dans la baie de Fundy et dans la région "Le Gully", à l'est de l'île de Sable. Les régions les m000ins diversifiées se trouvaient dans la région du banc de La Have et dans la région de mi-profondeur au sud du banc Banquereau. Dans la plupart des régions, l'automne était la saison la plus diversifiée et la baie de Fundy le secteur le plus riche.

La complexité relative et la dynamique des communautés trouvées dans les zones extracôtières ont été résumées en fonction des tracés de la composition respective des espèces, et la fréquence des occurrences de toutes les espèces a été signalée selon la saison et le moment. En été, on a décelé des diminutions à long terme de la fréquence des occurrences de 26 espèces, les cas les plus marqués étant notamment la raie lisse (Raja senta), la raie épineuse (Raja radiata), la baudroie (Lophius americanus), le brosme (Brosme brosme), l'aiglefin (Melanogrammus aeglefinus) et le poisson-loup (Anarhichas lupus).

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INTRODUCTION

The biodiversity of marine ecosystems isdifficult to assess given their size and theinaccessibility of the organisms involved. TheScotia-Fundy bottom trawl surveys, althoughgeared towards the assessment of commerciallyimportant groundfish, provides a means ofstudying a relatively large marine ecosystem.

The Scotia-Fundy summer surveystratification scheme, in place since 1970, wasused to summarize the relative differences in thefinfish diversity of offshore areas. The scope ofthe database enabled the examination of the totalspecies composition of each area, and thefrequency of occurrence for each species, byseason (1979-85), and for summer data from1970-93. By examining seasonal and long-termsummer data, it was possible to identify timeperiods and localities that were the most dynamicor stable in terms of community structure.

METHODS

when the "Lady Hammond" was used. All springand fall surveys from 1979-85 were conductedwith the "Lady Hammond," the Western IIA beingused exclusively.

FISHING PROTOCOLS

A tow duration of 30 min and speed of3.5 knots was targeted for all survey sets, toachieve a towed distance of 1.75 naut mi. Warpto depth ratios were adjusted on the "A.T.Cameron" to achieve a constant gear spread withfishing depth, whereas a constant scope of 3:1was employed on the "Lady Hammond" and"Alfred Needler." Only tows of a minimum 20 minduration and maximum of 40 min wereconsidered representative provided there was nodamage to the trawl. For more documentation onsurvey protocols, refer to the Manual for MarineFish Bottom Trawl Surveys of the Scotia-FundyRegion by M. Strong and S. Gavaris, available atthe Biological Station, St. Andrews N.B. EOG2X0.

DATA SOURCE

Canadian Department of Fisheries andOceans bottom trawl surveys in the Scotia-FundyRegion have been conducted every summersince 1970, and every spring and fall from 1979to 1985 for the Scotian Shelf, Gulf of Maine andBay of Fundy. The surveys used a stratified-random sampling scheme of 48 strata (Fig. 1)numbered from 440-495, and the sampling stratawere defined on the basis of location (Fig. 2) anddepth increments of 50 fath (Doubleday 1981).Sampling effort was initially allocated based uponstratum area with a default of two stations forsmall strata. Station allocation was subsequentlyadjusted according to the historic abundances ofcod, haddock and pollock.

VESSELS AND SAMPLING GEAR

The research vessel "A.T. Cameron" wasused from 1970-81 for summer surveysemploying a Yankee 36 ottertrawl. In 1982, the"Lady Hammond" was used with an AtlanticWestern IIA trawl, and thereafter, the "AlfredNeedler" with the same gear, except in 1990

DATA ANALYSIS

Summer data 1970-93

Sampling effort and effectiveness

Sampling effort was determined as theratio of the number of representative survey setsto the stratum area. Cumulative distributions ofthe number of previously unobserved species perstratum were used to evaluate the effectivenessof the sampling in resolving true speciescomposition, recognizing this measure might alsoreflect changes in sampling effort and incidentalvisitations of exotic species. The rate at whichpreviously unobserved species were beingreported per stratum was determined byregression on these values since 1984. Thosestrata with the lowest slopes were considered thebest sampled.

Index of species diversity

A community is deemed to be highlydiverse if it has many species and theirabundances are fairly even, and less so if it hasfew species and abundances of uneven

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distribution (Pielou 1969). The relative diversity ofeach stratum was assessed using the meannumber of species captured per tow. As a crudemeasure of abundance, the frequencies ofcapture for each species per stratum wasdetermined.

Trends in diversity with time

Contour mappinp of diversity by time period.The number of species captured perrepresentative survey set and positional datawere determined by 4-yr time period from 1970-93. Contour plots were produced using Aconsoftware (Black 1993), which aggregated the datainto 5 naut mi squares and performed contouringby Delauney triangulation and an inversedistance weighted smoothing gradient algorithm(Watson and Philip 1985). Areas considered ashaving high diversity reported 15 species or moreper tow, and those of low diversity reported fiveor less.

Long-term trends in diversity acrossstrata. A median polish of the mean number ofspecies per tow (mspt) in every stratum and yearwas used to reduce the observed values intotrend and residual components (Tukey 1977).Residual values were tested for any remainingyear and stratum effects and the presence of ayear by stratum interaction. The time series oftrend values was modeled using regressiontechniques.

resolved on the database, and may only bereported to the family level, or incorrectly to thespecies level. These would include primarilygroups such as the Zoarcids (eelpouts),Myctophids (lanternfishes), the Rajids (skates),Cottids (sculpins), Cyclopterids (lumpfish andseasnails), Agonids (alligatorfishes), and theStichaeids (blennies and shannies). Unresolvedspecies are reported in this document as non-specific categories as they are recorded in theregional research surveys database, and areindicated by the common name followed by "NS"or "unseparated" on the axis labels of the speciescomposition plots.

The species composition for each stratumwas determined, and species were rankedaccording to their frequency of occurrence; aratio of the total number of tows in which aspecies was observed and the total number ofvalid tows for a given time period. The frequencyof occurrence of each species was calculated foreach 4-yr period since 1970 to reveal trends withtime.

In order to assess the stability of thesummer communities found within each stratum,species were classified as either residents ortransients based on theirfrequency of occurrenceduring the 24-yr sampling period, and thepercentage within each category wasdetermined. The categories were defined asfollows.

Species composition and frequency ofoccurrence

Species identification was routinelyperformed at sea by Department of Fisheries andOceans staff using the current referenceliterature. Verifications were performed whennecessary by returning specimens to the AtlanticReference Centre. The degree of taxonomicresolution tended to increase with time as morestringent sampling protocols were applied. Anumber of species originally grouped togetherwere later resolved into two or more species.Examples of this include offshore hake and silverhake, black-bellied rosefish and redfish (still agrouping of three other species), red hake andwhite hake, little skate and winter skate, bluebackherring and gaspereaux. A number of taxonomicgroups with many species still remain poorly

Summer residents: Species wereconsidered residents if they were present in fouror more of the six time periods since 1970.

Summer transients: Species thatoccurred in three or fewer time periods since1970 were regarded as transients. These specieswere typically of very low frequency, andconsisted of incidental migrants or remnants ofpopulations that were residents during anotherseason. It is recognized that some species, dueto a restricted distribution within a stratum, lowabundance, or constraints of the sampling gearused, may not have been caught with sufficientfrequency to qualify as residents, even thoughthey always inhabit a given stratum.

Summer immigrants: Species thatoccurred in the last three consecutive periods

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with increasing frequency of occurrence were considered immigrants.

Summer emigrants: Species that did not appear in the last two time periods after successive decreasing frequencies of occurrence,were considered emigrants from that stratum.

Species diversity by strata group

Strata were generally placed into five groups based on their bathymetry and geography. The degree to which strata characteristics were associated with species diversity was investigated by examining the distribution of stratum groups relative to the total number of species repo rted per stratum and the mean number of species reported per tow. The strata were grouped as follows.

Gulf of Maine and Bay of Fundy: These areas (strata 484, 485, 490-495) are generally under the influence of strong tidal mixing by the Fundy tides, and have the coastal influence of estuaries and river systems in the Bay of Fundy.

Basins: These areas (strata 461, 471, 482, 483) were all >100 fath. LaHave (471) and Emerald (461) are landlocked by shallower Scotian Shelf strata. The Gulf of Maine basins (482, 483) are somewhat different as they are influenced by the Fundian Channel and the Bay of Fundy tides.

Banks: These areas (strata 447, 448, 455, 456, 458, 463, 464, 473, 474, 475, 480) were all under 50 fath, of relatively uniform bathymetry, and have been heavily exploited by bottom trawls for c,ommercially important species.

Edge: These areas (strata 440-446, 451- 453, 459, 466, 478) fringe the continental shelf, have great ranges in bathymetry, and are influenced by external hydrography. Strata 440- 446 are heavily influenced by waters discharged by the Gulf of St. Lawrence, while the remaining strata are influenced by slope waters of the continental shelf.

Mid-depth: These areas (strata 449, 450, 454, 457, 460, 462, 465, 470, 472, 476, 477,

481) occupy the 51-100 fath range between banks and basins on the Scotian Shelf.

Seasonal data 1979-85

Contour mapping of diversity

Using the same methods described under summer data, contour plots of the mean number of species captured per tow from representative sets were plotted for the three seasons defined by the following aggregations: spring (February, March, April), summer (June, July, August), and fall (September, October, November).

Species composition and frequency of occurrence

The species composition and the frequencies of occurrence of each species was determined by season for each stratum from spring, summer, and fall survey data. Frequencies of occurrence were determined as the ratio of the number of representative survey sets in which a given species was observed in a given season relative to the number of representative survey sets performed in that season.

Seasonal impact on species inventory and diversity

The relative seasonal dynamics of the communities found in each stratum was assessed by determining the percentage of species that were present year round as opposed to those that were seasonal in nature. The following groupings were used.

Native: Species that were present within a stratum in all seasons sampled (spring, summer and fall).

Seasonal: Species that were present within a stratum in two seasons or less.

The seasonal effect on the total number of species reported and the mean number of species per tow (diversity) was examined using the same strata groupings as the summer data.

4

RESULTS

DATA ANALYSIS

Summer Data

Sampling effort and its effectiveness

The sampling effort per stratum was determined by the number of tows completed per naut mi2 since 1970 (Table 1), and by the number of valid tows per 4-yr time period (Table 2). The effectiveness of the sampling in providing a good assessment of the species composition of the summer communities found within each stratum was assessed by examining the cumulative distributions of new species since 1970 (Fig. 3-10) and by the rate at which new species were being reported per year since 1984 (Table 1). To summarize sampling effort and effectiveness, a distribution of strata by sampling density and the rate of new species acquisition is given in Fig. 11.

Most strata appeared to be well sampled for species composition, in that the rate at which new species were reported became low in the later part of the sampling period despite the effect of improving taxonomic resolution, suggesting that the species composition of the samples were representative of the complete species inventories of the strata. The strata that were poorly sampled included many of the edge strata such as 440, 441, 442, 444, 445, 452 and 466. In most cases, ineffective sampling occurred due to low sample densities. However, strata 452 and 466 demonstrated high rates of species acquisition in spite of relatively high sampling effort. The Basin and Fundy strata appeared to be well sampled with a minimum of sampling effort, with the exception of strata 482 and 484 which are deep water regions in the Gulf of Maine. Most of the Banks strata appeared to be adequately sampled except strata 448 (Banquereau Bank), 464 (Western Bank), 456 (Sable Island Bank) and 475 (Baccaro Bank), the last of which had a very high sampling density. The mid-depth strata were generally well sampled except strata 460 and 465 which are found north and south of Emerald Basin.

Species diversity by time period from contour plots

The contour maps of species diversity for the six time periods from 1970-93 indibated spatial and temporal shifts in diversity (Fig. 12- 17). Note that because stratum boundaries are overlaid on each plot, individual strata or other features such as banks or basins can be identified using Figures 1 and 2 as keys. A summary of the sampling effort, the mean number of species per tow, and total number of species reported, by time period, can be found by stratum in Table 2. The trends found in diversity by area and time are described below where the time periods are: period 1 (1970-1973), period 2 (1974-1977),period 3 (1978-1981), period 4 (1982-1985), period 5 (1986-1989) and period 6 (1990-93).

Hiqh diversity areas. In time period 1, the only area of high diversity was in the Bay of Fundy. This region, associated with coastal Nova Scotia from Methegan to Digby (stratum 490), expanded with time until the end of time period 3 and persisted until period 6 . By time period 4, additional areas of high diversity developed southwest of the Saint John river and southwest of Grand Manan and persisted until period 6.

In the remainder of the Scotia-Fundy region, centers of high diversity appeared in periods 2-6, but none were as persistent in terms of location as those in the Bay of Fundy. The "Gully" area (stratum 452) demonstrated high diversity in periods five and six (1986-93). Other areas of periodic high diversity appeared to the north and west of Middle Bank (periods 2,4,5 and 6), on northeast Emerald Basin (stratum 461; periods 4 and 6), along coastal Nova Scotia (strata 470, 476, 481; periods 2, 4 and 5), west of Sable Island (strata 455, 456; periods 4, 5 and 6) and on northwest Western Bank (stratum 464; • period 6).

Stratum diversities given for 4-yr increments (Table 2) revealed a period of high diversity between 1982 and 1985. Eighteen strata recorded their highest diversity during this time, compared to frequencies of 5-9 strata for the other time periods.

5

Low diversity areas. Several areas demonstrated consistently low diversity throughout the time series. These regions were LaHave Bank, Baccaro Bank and Roseway Bank (strata 473 to 477), the Emerald Bank area (strata 463, 465), the Misaine Bank area (strata 443, 444, 445), and the Banquereau Bank area (strata 447, 448, 449).

Long-term trends in diversity across strata. A median polish of the mean number of species per tow in every stratum and year reduced the data into trend and residual components. An analysis of variance determined that the residual component was devoid of any year, strata or year by strata effects. A regression of the trend values on time indicated a significant addition of new species between 1970-93 (b=.039,P<.05 ; a=5.87, P<.05) (Fig. 18). The regression of trend values on the two halves of the time series resulted in a different interpretation. During the period the Cameron was active (1970-81) there was no change in species per tow (b=-.017,P>.05 ; a=9.92, P<.05). In the time period that the "Needier" was active (1982-93) there were more species per tow caught but also a significant decline since its inception (b=-.059,P<.05 ; a=14.61). All regressions of the trend values on time for individual strata were identical to those above except for differences in the intercepts.

Species composition and frequency of occurrence

Species composition and frequency of occurrence by stratum are depicted in Fig. 19-66. Common names of the species are used in these figures and in the following text, and the corresponding scientific names are listed in Table 3.

The plots of frequency of occurrence by time period revealed a decreasing frequency of occurrence for 26 species. The most severely affected species, in decreasing order of magnitude, were smooth skate (20 strata), thorny skate (12 strata), anglerfish (10 strata), cusk (9 strata), haddock (8 strata), wolffish (7 strata), halibut (6 strata), dogfish and witch (5 strata), and hagfish and white hake (4 strata). The trend of increasing frequency of occurrence occurred less often, with only 15 species affected, 13 of

which affected only a single stratum. Pollock and herring increased in occurrence in 5 and 4 strata respectively.

The most dynamic strata in terms of diminishing frequencies of occurrence were strata 458 (6 species), 454, 459, 461 and 492 (5 species), 446, 462, 463, 466, 472, 473 and 477 (4 species) and 451, 456, 465, 470, 480 and 493 (3 species). The most dynamic strata in terms of recruiting new species were 485 (4 species) and 453 (3 species).

Although the frequency of occurrence seemed to diminish for a greater number of species and strata, the latest time periods exhibited the greatest increase in the number of species captured per stratum (Table 2). Thus the inventory of species may be increasing in the Scotia-Fundy Region even though certain species are in decline.

Species inventory and diversity by strata group

The stability of the species composition of the summer communities with time was examined by determining the percentages of species that remained residents throughout the sampling period. The percentage of species per stratum considered long-term residents ranged from 34-74%, and are reported in the general summaries per stratum. Generally, the edge strata reflected the least stable summer community with only 44% of the species identified as long term residents. This was followed by the basins (51.5%), banks (55.1%), mid-depth strata (55.4%) and the Fundy strata with 58.8% of the species qualifying as long-term residents.

The distribution of strata relative to the total species inventory and the number of mean species captured per tow is depicted in Fig. 67. Letter symbols and stratum numbers were used to identify strata grouped together on the basis of similarities in their bathymetry and geography. Based on frequency of capture and total species inventory alone, similarities among the strata emerge that relate to the strata groups.

The strata that repo rted a high species inventory and demonstrated a high frequency of capture were best typified by the Bay of Fundy

6

and Edge strata. Examples of these strata include 490, 493, 491, 452, 492, 485, 446, and 478.

Strata that repo rted a high species inventory with species of a low frequency of capture was characteristic of the Edge and Mid-depth strata. Examples of these strata included 442, 444, 465 and 466.

Strata that reported a low species inventory with species of average to high frequency of capture were represented by all groups including most of the Basin group, examples of these strata including 470, 476, 461 and 471.

Strata that had a low species inventory with species of a low frequency of capture were best typified by the Banks group. Examples of these strata include 473, 449, 474, 475, 447 and 463.

Seasonal data

Sampling adequacy

The reader is cautioned that because the number of species reported increases with the number of stations observed, that a valid comparison of the number of species repo rted by season for some strata may be biased due to large inequities in the number of stations observed per season, as in strata 440-444 (Table 4). Inadequate sampling effort in the springtime may reflect fewer species relative to other seasons for the edge strata (Fig. 119). These areas are frequently inaccessible due to the presence of pack ice in the spring, and consequently may never be sampled adequately.

Contour mapping of species diversity

Spring. A contour plot of the springtime diversity can be found in Fig. 68. The distribution of high diversity areas during this season was very fragmented with many small aggregations. The areas of highest diversity in the springtime were primarily in the region south of Grand Manan in the Bay of Fundy (strata 492 and 493), with smaller areas represented in strata 485 and 490. Other areas of high diversity during

springtime included a large area between the Bacarro and LaHave banks that extended from LaHave Basin to the edge of the Scotian Shelf (strata 477, 476, 477, 478, 466, 453), the western edge of Western Bank (strata 462, 465), areas west of Middle Bank (strata 459, 462), coastal Nova Scotia (stratum 470), no rthern LaHave Basin (stratum 471), and the Gully area (stratum 452). Areas of low diversity were apparent in the Misaine Bank area (strata 443, 444, 445), Banquereau Bank (strata 447,448), Laurentian Edge (strata 446, 449), Middle Bank (stratum 458), Sable Island region (strata 455, 456, 464), Emerald Bank (stratum 463), LaHave Bank (stratum 473) and Roseway Bank (stratum 474).

Summer. A contour plot of the summer diversity can be found in Fig. 69. Areas of high diversity appeared to diminish in number and size in the summer season. High diversity concentrations in the Bay of Fundy shifted southeastward from spring locations to strata 485 and 490, with smaller areas evident in strata 491 and 492. Other points of high diversity included an area north of Eastern Brown's Bank (stratum 481), the no rtheastern Emerald Basin area (strata 460, 461), and an area north of Middle Bank (stratum 459). Areas of low diversity included coastal Cape Breton (stratum 442), the Laurentian Edge (strata 440, 446, 449), the Misaine Bank area (strata 443, 444, 445), Banquereau Bank (strata 447, 448), the Eastern Sable Island area (strata 454, 455, 456, 457), southern Emerald area (strata 463, 465), LaHave Bank (stratum 473), Roseway Bank (stratum 474), and an area south of Brown's Bank (stratum 481).

Fall. A contour plot of the spring diversity can be found in Fig. 70. The distribution of high diversity sites in the fall became more fragmented than in the summer, but not to the extent found in the spring. Once again, the Bay of Fundy demonstrated the highest diversity. The distribution patterns within the Bay of Fundy expanded and shifted relative to the summertime to the interior of the bay, with a large concentration along the western borders of strata 494 and 495, bridging the bay from Saint John to Digby. Another large region of high diversity occurred along the southwestern coastal region of Nova Scotia north of Brown's Bank (strata 476,

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481, 485), a vestige of which was present in thesummer distribution. Other small patches wereevident along the edge of the Scotian shelf(strata 478, 466, 453, 451), the Gully (stratum452), central Western Bank (stratum 464), and inthe region of the Owl and the Cowpen in stratum462. Areas of low diversity included the MisaineBank Region (strata 443, 444, 445), coastal CapeBreton (stratum 442), the eastern Sable Islandregion (strata 455, 456), Middle Bank (stratum458), the Emerald Bank area (strata 463, 465),LaHave Bank (stratum 478), Roseway Bank(stratum 474), and the western Brown's Bankregion (strata 480, 481).

Species composition and frequency ofoccurrence

The frequency of occurrence of allspecies reported per stratum are depicted byseason in Figures 71-118. Common names ofspecies are used in these figures, and thecorressponding scientific names are found inTable 3.

summer and fall being the seasons with the mostspecies reported. The number of speciesreported in the edge strata was found to increasedramatically from the spring to the summer,which may be indicative of the arrival of migratoryvisitors. However, the previously mentioned biasin sampling may have caused under-representation of the true species compliment inthe spring. The basin strata were noted tochange little in the number of species reported byseason.

A summary of the mean number ofspecies captured per tow by stratum and seasoncan be found in Table 4, and in the generalsummaries by stratum. An examination of Fig.119 reveals a trend for the mid-depth, edge andFundy strata to decrease in diversity from springto summer, and then to increase from summer tofall. The banks and basins demonstrate acontinuous increase in diversity from spring tofall, although the basins change little by season.

Summary of high diversity strata byseason

Seasonal impact on species inventoryand diversity

The percentage of the total number ofspecies that occurred in a given season, and therate of residency of species that remained in allseasons, is reported by stratum in Table 5 and inthe general summaries.

The rate of year-round residency rangedfrom 19-67%. When examined by strata group,the edge strata were found to have the lowestwith only 41.5% of the species reported presentin all seasons, representing the group mostdynamic seasonally. This group was followed bythe basin strata (48.2%), Fundy and bank strata(50.6%), and the mid-depth strata with 53.9%.

A summary of the number of speciesreported and the diversity of each group of strataby season is given in Fig. 119. The residencyrates by season and stratum (Table 5) indicatethat 27 strata experienced the highest number ofspecies in the fall, followed by 20 and 8 strata inthe summer and spring, respectively. The groupsof strata that demonstrated the highestinventories were the edge and Fundy strata, with

The fall was generally the season ofgreatest diversity for the majority of strata. Thefollowing is a summary of the strata exhibiting thegreatest diversity by season.

Spring. The strata exhibiting the highestdiversity in this season include strata 440, 443,445, 446, 449, 450, 451, 459, 460, 462, 465,466, 470, 471, 475, 476, 477, 482, 484 and 492.Note that these strata were almost exclusivelydeep and mid-depth areas, with the exception ofstrata 443 and 475.

Summer. The strata exhibiting the highestdiversity in this season include strata 447, 455,472, 474 and 483. These strata were bank areasexcept strata 472 and 483.

Fall. The strata exhibiting the highestdiversity in this season include strata 441, 442,444, 448, 452, 453, 454, 456, 457, 458, 461,463, 464, 473, 478, 480, 481, 485, 490, 491,493, 494 and 495. With the exceptions of strata452, 453, 461, and 478, these strata were mainlyshallow coastal, bank, and mid-depth areas.

8

GENERAL SUMMARIES BY STRATUM

Stratum 440: The Laurentian Edge (north)

This stratum occupies the 51-100 fathcontour inshore of stratum 440, and covers 1000naut mi2, about the average stratum area.

This stratum is found in depths >100 fathoff Cape Breton along the Laurentian Channel,and occupies an area of 924 naut mi2, smallerthan the average stratum size of 1042 naut mi2.

Sampling effort during summer surveysincreased in 1985 from 3 to 4 stations, with atotal of 83 stations fished successfully. Thisrepresents a sampling effort of 0.09 stations pernaut mi2, below the average sampling level of0.12 stations per naut mi2. The rate of capture ofnew species since 1984 was relatively high at1.12 species per year, indicating that this stratumis poorly sampled for species composition (Table1 and Fig. 3, 11).

A total of 53 species have been reportedin this stratum from summer surveys, well abovethe average of 40 species for all strata (Fig. 19).Of the total species reported, only 34% wereclassified as long-term summer residents, theremaining species being transient in nature. Thediversity of the summer community as measuredby the mean number of species per tow fromsummer survey data was about average at 9.6 ±0.3.

Examining seasonal data from 1979-85,42 species were reported ( Fig. 71). Of these,36% were considered year-round residents, andthe remainder as seasonal species. The seasonreporting the most species was the summer, with88% present, in comparison to 76% and 43%present in the fall and spring respectively (Table5). The relative diversity by season from seasonalsurvey data as measured by the mean number ofspecies captured per tow was greatest in thespring with 12, followed by 11 in the fall and 10in the summer (Table 4). Species stronglyinfluenced by season include marlin spikegrenadiers, long-finned hake, hagfish, dogfishand striped woiffish as summer/fall residents.Other species like sea raven and northernwolffish are strictly springtime residents.

Sampling effort on summer surveysincreased from 3-5 stations in 1985, with a totalof 85 stations fished successfully. This representsa sampling effort of 0.09 stations per naut miz,which below is the average sampling level of0.12 stations per naut mi2 for all strata. The rateof capture of new species since 1984 wasrelatively high at 1.28 species per year, indicatingthat this stratum is poorly sampled for speciescomposition (Table 1, Fig. 3, 11). The diversity ofthe summer community as measured by themean number of species per tow from summersurvey data was about average at 9.1 ±0.4.

A total of 49 species have been reportedin this stratum from summer survey sets, abovethe average of 40 species for all strata (Fig. 20).Of the 49 species reported, 43% are classified aslong term summer residents. The remaining 51%are low frequency species classified astransients, being either visitors from another areaor species normally found in another season.

Examining seasonal data from 1979-85,47 species were reported ( Fig. 72). Of these,32% of the species were considered year-roundresidents, and the remainder as seasonalspecies. The season reporting the most specieswas the summer, with 79% present, incomparison to 72% and 38% present in fall andspring respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with10.7, followed by the spring and summer with 9.7(Table 4). Species strongly influenced by seasoninclude summer and fall natives like haddock andwitch which are not present in the spring.

Stratum 441: Cape Breton mid-depths

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Stratum 442: Coastal Cape Breton

This stratum is found in depths less than50 fath east of Cape Breton and occupies anarea 1437 naut mi2, slightly larger than theaverage stratum.

Sampling effort during summer surveyswas historically maintained at 3 stations, butincreased from 1985-93 to 6 stations, with a totalof 88 stations fished successfully. This representsa sampling effort of 0.06 stations per naut mi2,which is less than the average of 0.12 stationsper naut mi2. The rate of capture of new speciessince 1984 was very high at 1.43 species peryear, indicating that this stratum is poorlysampled for species composition (Table 1, Fig. 3,11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was very low at5.6±0.3, which is far below the mean 9.1 for allstrata.

A total of 48 species have been reportedin this stratum from summer surveys (Fig. 21).This is above the average of 40 species for allstrata. Of the 48 species reported from summersurveys, only 35% were classified as long termsummer residents, the remaining species beingtransient in nature. Of the long-term summerresidents, haddock and long-horned sculpinsappear to be in serious decline. Of the transientspecies, spiny dogfish appear to be potentialimmigrants as summer residents.

Examining seasonal data from 1979-85,42 species were reported (Fig. 73). Of these,only 19% of the species were considered year-round residents, and the remainder as seasonalspecies. The season reporting the most specieswas the summer, with 76% present, incomparison to 67% and 26% present in fall andspring, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with 7.4species, followed by 6.3 in the summer and 5.3in the spring (Table 4). Species stronglyinfluenced by season include summer and fallnatives like thorny skate, haddock, white hake,smooth skate which all but disappear in thespring. Species like winter skate and arctic

eelpout are strictly springtime residents. Fallspecies include silver hake and mackerel.

Stratum 443: Misaine Bank

This stratum is found in depths less than50 fath in the Misaine Bank area and occupiesan area 1318 naut mi2, slightly larger than theaverage stratum. This stratum is fragmentedwithin an area of mixed depths represented alsoby stratum 444 (51-100 fath) and stratum 445(>100 fath), and therefore does not represent asingle region.

Sampling effort during summer surveyshas remained unchanged at 4 stations, with atotal of 91 stations fished successfully. Thisrepresents a sampling effort of 0.07 stations pernaut mi2, which is below the mean of 0.12stations per naut mi2 for all strata. The rate ofcapture of new species since 1984 was very lowat 0.38 species per year, indicating that thisstratum is well sampled for species composition(Table 1, Fig. 3, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data wasvery low at 5.6±0.2, which is far below the meanof 9.1 for all strata.

A total of 35 species have been reportedin this stratum from summer surveys (Fig. 22),which is below the average of 40 species for allstrata combined. Of the 35 species reported fromsummer surveys, 46% were classified as longterm summer residents, the remaining speciesbeing transient in nature. Of the long termsummer residents, yellowtail and witch appear tobe in serious decline.

Examining seasonal data from 1979-85,37 species were reported (Fig. 74). Of these,49% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer, with 78% present, incomparison to 70% and 62% in the fall andspring respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with6.7 species, followed by 6.4 in the fall and 6.0 inthe summer (Table 4). Species stronglyinfluenced by season include witch as a summerresident, lumpfish as spring resident, winter skate

10

as a summer/fall resident, and silver hake as a strictly fall resident.

Stratum 444: Eastern Shelf mixed depths 51- 100 fath

This stratum is found in depths 51-100 fath in the Misaine Bank area and occupies an area 3,925 naut mi2 , almost four times as large as the average stratum. This stratum is fragmented within an area of mixed depths represented also by stratum 443 (<51 fath) and stratum 445 (>100 fath), and therefore does not represent a single region.

Sampling effort during summer surveys increased from 4 to 8 stations in 1990, with a total of 127 stations fished successfully. This represents a sampling effort of 0.03 stations per naut mi2 , which is far below the mean of 0.12 stations per naut mi 2 for all strata. The rate of capture of new species since 1984 was very high at 1.54 species per year, indicating that this stratum is poorly sampled for species composition (Table 1, Fig. 3, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was very low at 7.5+0.3, which is below the mean of 9.1 for all strata.

A total of 54 species have been reported in this stratum from summer surveys, above the average of 40 for all strata combined (Fig. 23). Of the 54 species reported from summer surveys, 43% were classified as long-term summer residents, the remaining species being transient in nature. Of the long-term summer residents, haddock appear to be in serious decline.

Examining seasonal data from 1979-85, 46 species were reported (Fig. 75). Of these, 46% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the summer, with 82% of the species present, in comparison to 67% and 59% in the fall and spring, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 9 species, followed by 8.6 in the spring and 7.8 in the summer (Table 4). Species strongly influenced by season include herring as a

spring/fall resident, silver hake and winter skate as summer/fall residents, and sea raven as strictly a spring resident.

Stratum 445: Eastern Shelf mixed depths >100 fat h

This stratum is found in depths >100 fath in the Misaine Bank area and occupies an area 1,023 naut mi2 , about the average stratum size. This stratum is fragmented within an area of mixed depths represented also by stratum 443 (1 50 fath) and stratum 444 (51-100 fath), and therefore does not represent a single region.

Sampling effort during summer surveys has remained unchanged at 4 stations, with a total of 99 stations fished successfully. This represents a sampling effort of 0.10 stations per naut mi 2 , slightly below the average s «ampling level of 0.12 stations per naut mi 2 . The rate of capture of new species since 1984 was very high at 1.25 species per year, indicating that this stratum is poorly sampled for species composition (Table 1, Fig. 3, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was average at 9.1+0.4.

A total of 57 species have been reported in this stratum from summer surveys, the highest level of all 48 sampling strata, well above the average of 40 species (Fig. 24). Of the 57 species reported from summer surveys, 40% were classified as long-term summer residents, the remaining species being transient in nature. As a summer resident, haddock has only been reported in the 1982-89 period.

Examining seasonal data from 1979-85, 54 species were reported (Fig. 76). Of these, 46% were considered year-round residents, and the remainder were classified as seasonal . species. The season reporting the most species was the summer, with 83% of the species reported, in comparison to 72% and 59% in the fall and spring respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 11.2 species, followed by 10.4 in the fall and 8.9 in the summer (Table 4). Species strongly influenced by season include yellowtail, herring,

11

halibut and lumpfish as spring species, long-finned hake as a summer/fall species, longhorned sculpin and red hake as a spring/fall species, mailed sculpin as a fall species, and dogfish as a summer species.

Stratum 446: The Laurentian Edge (south)

This stratum is found in depths >100 fath east of the Misaine Bank area along the Laurentian Edge and occupies an area 491 naut mi2 , about half the size of an average stratum.

Sampling effort during summer surveys has remained unchanged at 3 stations, with a total of 70 stations fished successfully. This represents a sampling effort of 0.14 stations per naut mi2 , above the average sampling level of 0.12 stations per naut mi 2. The rate of capture of new species since 1984 was relatively low at 0.79 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 4, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was higher than average at 10.4+0.4.

A total of 49 species have been reported in this stratum from summer surveys, above the average of 40 species for all strata c,ombined (Fig. 25). Of the 49 species reported from summer surveys, 43% were classified as long-term summer residents, the remaining species being transient in nature. As summer residents, fourbeard rocklings and hagfish appear to be diminished. Winter skate appear to be increasing in occurrence as a summer residents. Dogfish and haddock, normally springtime residents, are potential immigrants as long-term summer residents.

Examining seasonal data from 1979-85, 55 species were reported (Fig. 77). Of these, 38% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 75% of the species reported, in comparison to 73% and 29% in the summer and spring respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 11.9 species, followed by 11.4 in the summer

and 10.4 in the fall (Table 4). Species strongly influenced by season include yellowtail, herring, halibut and lumpfish as spring species, long-finned hake as a summer/fall species, longhorned sculpin and red hake as a spring/fall species, mailed sculpin as a fall species, and dogfish as a summer species.

Stratum 447: East Banquereau Bank

This stratum is found in depths < 50 fath south of the Misaine Bank area and occupies an area of 1616 naut mi 2 , larger than the average stratum size of 1043 naut mi 2 .

Sampling effort during summer surveys has increased from 4 to 7 stations since 1986, with a total of 121 stations fished successfully. This represents a sampling effort of 0.08 stations per naut mi2 , lower than the average sampling level of 0.12 stations per naut mi 2 . The rate of capture of new species since 1984 was relatively low at 0.65 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 4, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was lower than average at 7.3+0.3.

A total of 32 species have been reported in this stratum from summer surveys, below the average of 40 species for all strata (Fig. 26). Of the 32 species reported from summer surveys, 50% were classified as long-term summer residents, the remaining species being transient in nature. As summer residents, silver hake, mackerel and pollock have not been recorded since the 1986-89 period. Smooth skate, normally found year-round, appears diminished as a summer resident.

Examining seasonal data from 1979-85, 26 species were reported (Fig. 78). Of these, 50% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 88% of the species reported, in comparison to 77% and 69% in the summer and spring, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the summer with 8 species, followed by 7.3 in the fall and 7.1

12

in the spring (Table 4). Species strongly influenced by season include haddock, silver hake, witch, mackerel and angler as summer/fall species, and lumpfish as a spring species.

Stratum 448: West Banquereau Bank

This stratum is found in depths < 50 fath south of the Misaine Bank area and occupies an area of 1449 naut mi2 , slightly larger than the average stratum size.

Sampling effort during summer surveys has increased from 4 to 7 stations since 1986, with a total of 115 stations fished successfully. This represents a sampling effort of 0.08 stations per naut mi 2 , lower than the average sampling level of 0.12 stations per naut mi2 . The rate of capture of new species since 1984 was relatively low at 0.88 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 4, 11). The diversity of the summer c,ommunity as measured by the mean number of species per tow from summer survey data was lower than average at 6.9+0.3.

A total of 36 species have been reported in this stratum from summer surveys (Fig. 27), below the average of 40 species for all strata. Of the 36 species reported from summer surveys, 45% were classified as long term summer residents, the remaining species being transient in nature. As summer residents, smooth skate and silver hake appear to be diminished.

Examining seasonal data from 1979-85, 33 species were reported (Fig. 79). Of these, 52% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 88% of the species repo rted, in comparison to 73% and 64% in the summer and spring, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 8.5 species, followed by 7.8 in the summer and 6.7 in the spring (Table 4). Species strongly influenced by season include haddock, silver hake, witch, redfish and white hake as summer/fall species, and lumpfish and pollock as a spring/fall species.

Stratum 449: Southeastern Edge

This stratum is found in depths 51-100 fath southeast of the Banquereau Bank area and occupies an area of only 144 naut mi2 , the smallest stratum.

Sampling effort during summer surveys has remained constant at 2 stations per year since 1970, with a total of 47 stations fished successfully. This represents a sampling effort of 0.32 stations per naut mi2 , the highest sampling level of all strata. The rate of capture of new species since 1984 was relatively low at 0.15 species per year, indicating that this stratum is very well sampled for species composition (Table 1, Fig. 4, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was extremely low at 6.1+0.4.

A total of 24 species have been reported in this stratum from summer surveys, far below the average of 40 species for all strata (Fig. 28). Of the 24 species reported from summer surveys, 58% were classified as long-term summer residents, the remaining species being transient in nature. As summer residents yellowtail and smooth skate appear to be diminished.

Examining seasonal data from 1979-85, 28 species were reported (Fig. 80). Of these, 32% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the spring, with 79% of the species reported, in comparison to 64% and 60% in the fall and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 8.9 species, followed by 6.8 in the fall and 6.4 in the summer (Table 4). Species strongly influenced by season include witch as a summer/fall species, winter skate, halibut, pollock and wolffish as spring/summer species, and lumpfish as a spring species.

Stratum 450: East Gully Slope

This stratum is found in depths 51-100 fath southwest of the Banquereau Bank area and

13

occupies an area of 383 naut mi2, less than halfthe size of average strata.

Sampling effort during summer surveyshas remained at 3 stations per year, with a totalof 69 stations fished successfully. This representsa sampling effort of 0.18 stations per naut mi2,higher than the average sampling level of 0.12stations per naut miz. The rate of capture of newspecies since 1984 was relatively low at 0.61species per year, indicating that this stratum iswell sampled for species composition (Table 1,Fig. 4, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data wasslightly below average at 8.2±0.3.

A total of 36 species have been reportedin this stratum from summer surveys, below theaverage of 40 species for all strata (Fig. 29). Ofthe 36 species reported from summer surveys,50% were classified as long term summerresidents, the remaining species being transientin nature. As summer residents, angler andhagfish appear to be diminished. Longhornsculpin, normally a springtime resident, appearsto be increasing in occurrence.

Sampling effort during summer surveyshas remained at 2 stations per year, with a totalof 47 stations fished successfully. This representsa sampling effort of 0.32 stations per naut mi2,the second highest of all strata; the averagebeing 0.12 stations per naut mi2 for all strata. Therate of capture of new species since 1984 wasrelatively low at 0.75 species per year, indicatingthat this stratum is well sampled for speciescomposition (Table 1, Fig. 4, 11). The diversity ofthe summer community as measured by themean number of species per tow from summersurvey data was 9.9+0.5, signifying slightly higherdiversity relative to other strata which average 9.1species.

A total of 39 species have been reportedin this stratum from summer surveys, slightlybelow the average of 40 species for all strata(Fig. 30). Of the 39 species reported fromsummer surveys, 46% were classified as long-term summer residents, the remaining speciesbeing transient in nature. As summer residents,marlin spike grenadiers, anglers and cusk appearto be diminished. Spiny dogfish frequentlyoccurred in the 1982-89 period, but have notbeen reported since.

Examining seasonal data from 1979-85,40 species were reported (Fig. 81). Of these,48% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 75% species reported, incomparison to 70% and 68% in the summer andspring, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with10.8 species, followed by 10.7 in the fall and 8.7in the summer (Table 4). Species stronglyinfluenced by season include silver hake as asummer/fall species, and lumpfish and longhornsculpin as spring species.

Stratum 451: Scotian Shelf Edge (east)

This stratum is found in depths >100 fathsouth of the Banquereau Bank area and occupiesan area of only 147 naut miZ, the second smalleststratum. This stratum is very narrow running eastto west, bordering the southeastern edge of theScotian Shelf.

Examining seasonal data from 1979-85,51 species were reported (Fig. 82). Of these,45% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 78% of the species, incomparison to 61% in both the summer andspring (Table 5). The relative diversity by seasonfrom seasonal survey data as measured by themean number of species captured per tow wasgreatest in the spring with 11.9 species, followedby 9.9 in the fall and 9.9 in the summer (Table4). A species of high frequency stronglyinfluenced by season is dogfish, a spring/summerspecies.

Stratum 452: The Gully

This small stratum is found in depths>100 fath southwest of Banquereau Bank in anarea called "The Gully" and occupies an area of345 naut miZ. The bathymetry of this region iscomplex, and represents a major invagination ofthe Scotian Shelf edge.

14

Sampling effort during summer surveyshas remained constant at 2 stations per year,with a total of 53 stations fished successfully.This represents a sampling effort of 0.15 stationsper naut mi2, slightly above the average of 0.12stations per naut mi2. The rate of capture of newspecies since 1984 was relatively high at 1.1species per year, indicating that this stratum ispoorly sampled for species composition (Table 1,Fig. 5, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data was11.7±0.5, signifying higher diversity relative toother strata which average 9.1 species.

Sampling effort during summer surveysdecreased from 3 to 2 stations per year in 1987,with a total of 64 stations fished successfully.This represents a sampling effort 0.25 stationsper naut mi2, well above the average of 0.12stations per naut miz for all strata. The rate ofcapture of new species since 1984 was very lowat 0.22 species per year, indicating that thisstratum is very well sampled for speciescomposition (Table 1, Fig. 4, 11). The diversity ofthe summer community as measured by themean number of species per tow from summersurvey data was 9.2±0.4, about average diversityrelative to other strata.

A total of 45 species have been reportedin this stratum from summer surveys, above theaverage of 40 species for all strata (Fig. 31). Ofthe 45 species reported from summer surveys,49% were classified as long-term summerresidents, the remaining species being transientin nature. Yellowtail flounder were high frequencysummer visitors from the 1974-85 period, buthave since disappeared. Herring have madesignificant occurrences since 1986.

Examining seasonal data from 1979-85,54 species were reported (Fig. 83). Of these,39% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 76% species reported, incomparison to 63% and 57% in the summer andspring, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with14.6 species, followed by 12.3 in the summerand 12.1 in the spring (Table 4). Species stronglyinfluenced by season include four beard rocklingsand hagfish as summer/fall species, cusk andyellowtail as spring/summer species, alewife,longhorn sculpins and lumpfish as spring species,and herring and hookeared sculpins as fallspecies.

Stratum 453: Scotian Shelf Edge (Sable Islandarea)

This small stratum is found in depths>100 fath south of Sable Island along the edge ofthe Scotian Shelf, and occupies an area of 259naut mi2.

A total of 45 species have been reportedin this stratum from summer surveys, above theaverage of 40 species for all strata (Fig. 32). Ofthe 45 species reported from summer surveys,47% were classified as long-term summerresidents, the remaining species being transientin nature. Three high frequency residents thathave not been reported since the 1986-89 periodare cusk, monkfish and lanternfishes. Smoothskate and marlin spike grenadiers have similarlydiminished in frequency of occurrence. Haddock,pollock and cod have all increased in frequencyof occurrence, and may be potential immigrantsas summer residents.

Examining seasonal data from 1979-85,55 species were reported ( Fig. 84). Of these,47% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 75% of the species reported, incomparison to 67% and 64% in the summer andspring, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with12.8 species, followed by 12.7 in the spring and10.6 in the summer (Table 4). Species stronglyinfluenced by season include lanternfishes assummer/fall species, spiny dogfish asspring/summer species, and little skate as aspring species.

Stratum 454: Sable Slope

This small stratum is found in depths of51-100 fath south of Sable Island along the edge

15

of the Scotian Shelf, and occupies an area of 499 naut mi 2 .

Sampling effort during summer surveys decreased from 3 to 2 stations per year in 1987, with a total of 64 stations fished successfully. This represents a sampling effort of 0.13 stations per naut m 1 2 , slightly above the average of 0.12 stations per naut m 12 for all strata. The rate of capture of new species since 1984 was relatively low at 0.67 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 5, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 7.8+0.3, below the average of 9.1 species for all strata.

A total of 37 species have been reported in this stratum from summer surveys, below the average of 40 species for all strata (Fig. 33). Of the 37 species repo rted from summer surveys, 46% were classified as long-term summer residents, the remaining species being transient in nature. One summer resident that has not been reported since the 1986-89 period is sea raven. White hake, smooth skate, angler and halibut have all seriously diminished in frequency of occurrence as summer residents. Spiny dogfish was repo rted in high frequency in the 1982 to 1989 period, but has since disappeared.

Examining seasonal data from 1979-85, 49 species were reported (Fig. 85). Of these, 39% were considered year-round residents, and the remainder were classified as seasonal species. The season repo rt ing the most species was the fall, with 82% of the species reported, in comparison to 59% in the summer and spring (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 11.1 species, followed by 8.9 in the spring and 8.3 in the summer (Table 4). Species strongly influenced by season include white hake, redfish and sea ravens as summer/fall species, spiny dogfish as spring/summer species, long-finned hake and gulf stream flounder as spring/fall species, and lumpfish as a spring species.

Stratum 455: Sable Island Bank (south)

This stratum is found in depths of < 50 fath south of Sable Island, and occupies an area of 2122 naut m 1 2 , about twice the size of an average stratum.

Sampling effort during summer surveys was increased from 7 to 10 stations per year in 1990, with a total of 180 stations fished successfully. This represents a sampling effort of 0.09 stations per naut mi2 , below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was relatively low at 0.53 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 5, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.5+0.4, above the average of 9.1 species for all strata.

A total of 35 species have been reported in this stratum from summer surveys, below the average of 40 species for all strata combined (Fig. 34). Of the 35 species repo rted from summer surveys, 69% were classified as long-term summer residents, the remaining species being transient in nature. Monkfish, smooth skate and halibut have all seriously diminished in frequency of occurrence as summer residents. Pollock are recent immigrants to this stratum and are increasing in frequency of occurrence.

Examining seasonal data from 1979-85, 34 species were repo rted (Fig. 86). Of these, 58% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species is summer/fall, with 85% of the species reported, in comparison to 65% in the spring (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the summer with 10.5 species, followed by 9.9 in the fall and 7.6 in the spring (Table 4). Species strongly influenced by season include silver hake, witch, red hake, mackerel, white hake and monkfish as summer/fall species, and lumpfish as a spring species.

16

Stratum 456: Sable Island Bank (north)

This stratum is found in depths of < 50 fath no rt h of Sable Island, and occupies an area of 955 naut mi 2 , which is about average in area.

Sampling effort during summer surveys was increased from 6 to 8 stations per year in 1990, with a total of 146 stations fished successfully. This represents a sampling effort of 0.15 stations per naut mi2 , above the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was relatively high at 0.95 species per year, indicating that this stratum is poorly sampled for species composition (Table 1, Fig. 5, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.6+0.3, above the average of 9.1 species for all strata.

A total of 43 species have been reported in this stratum from summer surveys, above the average of 40 species for all strata (Fig. 35). Of the 43 species reported from summer surveys, 63% were classified as long-term summer residents, the remaining species being transient in nature. As in other strata, monkfish, smooth skate and halibut are occurring less frequently as summer residents.

Examining seasonal data from 1979-85, 39 species were reported (Fig. 87). Of these, 59% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species is summer/fall, with 82% of the species reported, in comparison to 72% in the spring (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 10.2 species, followed by 9.7 in the summer and 7.3 in the spring (Table 4). Species strongly influenced by season include silver hake, witch, herring, red hake, white hake, mackerel and ocean pout as summer/fall species.

Stratum 457: Gully Slope (west)

This stratum is found in depths of 51-100 fath north of Sable Island, and occupies an area of 811 naut mi2 , slightly smaller than the average stratum.

Sampling effort during summer surveys has remained constant at 2 stations per year, with a total of 54 stations fished successfully. This represents a sampling effort of 0.07 stations per naut mi2 , well below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was relatively low at 0.82 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 5, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 8.3+0.6, below the average of 9.1 species for all strata.

A total of 40 species have been reported in this stratum from summer surveys, about the average for all strata (Fig. 36). Of the 40 species reported from summer surveys, 48% were classified as long-term summer residents, the remaining species being transient in nature. Monkfish have disappeared as summer residents. Capelin are new high frequency visitors in the 1990-93 period.

Examining seasonal data from 1979-85, 42 species were reported (Fig. 88). Of these, 50% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 86% of the species reported, in comparison to 69% being reported in both the spring and summer (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 11.6 species, followed by 10.4 in the spring and 7.9 in the summer (Table 4). Species strongly influenced by season include redfish, silver hake, white hake and herring as summer/fall species, pollock and mailed sculpin as spring/fall species, and longfinned hake as a fall species.

Stratum 458: Middle Bank

This stratum is found in depths of < 50 fath north of Sable Island, and occupies an area of 658 naut mi2 , about half the area of an average stratum.

Sampling effort during summer surveys was increased from 3 to 8 stations per year in 1990, with a total of 97 stations fished

17

successfully. This represents a sampling effort of 0.15 stations per naut mi 2 , above the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was relatively low at 0.74 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 6, 11). The diversity of the summer community as measured by the mean number of species per tow from summer su rvey data was 7.4+0.2, below the average of 9.1 species for all strata.

A total of 34 species have been reported in this stratum from summer surveys, below the average of 40 for all strata (Fig. 37). Of the 37 species reported from summer surveys, 57% were classified as long-term summer residents, the remaining species being transient in nature. Monkfish and mackerel have disappeared as summer residents in the 1990-93 period. Smooth skate, white hake, halibut and wolffish all demonstrate greatly diminished frequencies of occurrence.

Examining seasonal data from 1979-85, 33 species were repo rted (Fig. 89). Of these, 49% were considered year-round residents, and the remainder were classified as seasonal species. No season demonstrates a noticeably greater species compliment in this stratum, with 73% of the species reported during the spring and fall, and 70% in the summer (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 8.7 species, followed by 8.1 in the summer and 5.1 in the spring (Table 4). Species strongly influenced by season include cod, haddock, silver hake, white hake and mackerel as summer/fall species.

Stratum 459: Mixed depths

This stratum is found in mixed depths north of Middle Bank, and occupies an area of 3148 naut mi2 , and at three times the size of an average stratum is second largest in area.

Sampling effort during summer surveys was increased from 4 to 6 stations per year in 1989, with a total of 104 stations fished successfully. This represents a sampling effort of 0.03 stations per naut mi2 , far below the average

of 0.12 stations per naut mi2 . The rate of capture of new species since 1984 was relatively low at 0.48 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 6, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.9+0.4, above the average of 9.1 species for all strata.

A total of 50 species have been reported in this stratum from summer surveys (Fig. 38), which is above the average for all strata. Of the 50 species reported from summer surveys, 66% were classified as long-term summer residents, the remaining species being transient in nature. White hake, monkfish, smooth skate, red hake and mackerel all demonstrate greatly diminished frequencies of occurrence in the 1990-93 period. Vahl's eelpout, capelin and sea poachers are all increasing in frequency of occurrence.

Examining seasonal data from 1979-85, 51 species were reported (Fig. 90). Of these, 65% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the summer, with 92% of the species reported compared to 71% and 73% in the spring and fall, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 11.2 species, followed by 11 in the fall and 10.3 in the summer (Table 4). Species strongly influenced by season include ocean pout, hookeared sculpins and argentine as summer/fall species, capelin as a spring/summer species, and dogfish as a fall species.

Stratum 460: Emerald Coastal

This stratum is found in depths of 51-100 . fath north and west of Emerald Basin, and occupies an area of 1344 naut mi 2 , about average in stratum area.

Sampling effort during summer surveys was increased from 2 to 3 stations per year in 1989, with a total of 56 stations fished successfully. This represents an average of 0.04 stations per naut mi2 , far below the average of 0.12 stations per naut mi 2 . The rate of capture of

18

new species since 1984 was relatively high at 1.01 species per year, indicating that this stratum is poorly sampled for species composition (Table 1, Fig. 6, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 10.3+0.5, above the average of 9.1 species for all strata combined.

A total of 40 species have been reported in this stratum from summer surveys, about the average for all strata (Fig. 39) . Of the 40 species repo rted from summer surveys, 55% were classified as long-term summer residents, the remaining species being transient in nature. Wolffish and sea ravens have ceased to be repo rted as summer residents in the 1990-93 period. Argentine and ocean pout demonstrate greatly diminished frequencies of occurrence in the 1990-93 period. Cusk appears to be increasing in frequency of occurrence.

Examining seasonal data from 1979-85, 36 species were reported (Fig. 91). Of these, 67% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the summer, with 86% of the species reported compared to 83% and 75% in the spring and fall, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 12.7 species, followed by 11.7 in the summer and 10.6 in the fall (Table 4). Species strongly influenced by season include alewives as a spring/summer species, hagfish and fourbeard rockling as spring/fall species, and smooth skate as a spring species.

Stratum 461: Emerald Basin

This stratum is found in depths >100 fath east of La Have Basin, and occupies an area of 1154 naut mi2 , about average in size.

Sampling effort during summer surveys has remained constant at 2 stations per year, except for 1987 and 1986 when 3 stations were fished, with a total of 50 stations fished successfully. This represents a sampling effort of 0.04 stations per naut mi 2 , far below the average of 0.12 stations per naut mi 2 . The rate of capture

of new species since 1984 was very low at 0.33 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 6, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.0+0.4, matching the average of 9.1 species for all strata.

A total of only 30 species have been repo rted in this stratum from summer surveys, which is below the average of 40 for all strata (Fig. 40). Of the 30 species reported from summer surveys, 50% were classified as long-term summer residents, the remaining species being transient in nature. Thorny skate and smooth skate have ceased to be reported as summer residents in the 1990-93 period. Witch, spiny dogfish and haddock demonstrate greatly diminished frequencies of occurrence in the 1990-93 period.

Examining seasonal data from 1979-85, 32 species were reported (Fig. 92). Of these, 47% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the summer/fall period, with 72% of the species reported compared to 66% in the spring (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 10.9 species, followed by 10.7 in the summer and 10 in the spring (Table 4). Species strongly influenced by season include mackerel as a summer species, and alewives as a spring species.

Stratum 462: Emerald Mid-Depths (north)

This stratum is found in depths of 51-100 fath east of Emerald Basin, and oc,cupies an area of 2116 naut mi2 , twice the area of an average • stratum.

Sampling effort during summer surveys has remained constant at 4 stations per year, with a total of 100 stations fished successfully. This represents a sampling effort of 0.05 stations per naut mi2 , far below the average of 0.12 stations per naut mi2 . The rate of capture of new species since 1984 was 0.72 species per year, indicating that this stratum is adequately sampled

19

for species composition (Table 1, Fig. 6, 11). Thediversity of the summer community as measuredby the mean number of species per tow fromsummer survey data was 10.0±0.3, slightly abovethe average of 9.1 species for all strata.

A total of 39 species have been reportedin this stratum from summer surveys, which isabout average for all strata (Fig. 41). Of the 39species reported from summer surveys, 62%were classified as long-term summer residents,the remaining species being transient in nature.Thorny skate and argentine demonstrate greatlydiminished frequencies of occurrence in the1990-93 period. Smooth skate and hagfish haveceased to be reported as summer residents inthe 1990-93 period.

Examining seasonal data from 1979-85,42 species were reported ( Fig. 93). Of these,67% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer, with 83% of the speciesreported compared to 76% and 79% in the springand fall, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with12.1 species, followed by 11.2 in the summerand fall (Table 4). Species strongly influenced byseason include alewives as a spring species, anddogfish, gulf stream flounder, buttertish andherring as spring/summer species.

Stratum 463: Emerald Bank

This stratum is found in depths of <50fath south of Emerald Basin, and occupies anarea of only 302 naut mi2, much smaller than themean stratum area of 1043 naut mi2.

Sampling effort during summer surveyshas remained constant at 2 stations per year,with a total of 50 stations fished successfully.This represents a sampling effort of 0.17 stationsper naut mi2, above the average of 0.12 stationsper naut mi2 for all strata. The rate of capture ofnew species since 1984 was very low at 0.20species per year, indicating that this stratum isvery well sampled for species composition (Table1, Fig. 6, 11). The diversity of the summercommunity as measured by the mean number of

species per tow from summer survey data was7.7±0.5, well below the average of 9.1 speciesfor all strata.

A total of 32 species have been reportedin this stratum from summer surveys, which isbelow the average of 40 for all strata (Fig. 42).Of the 32 species reported from summer surveys,63% were classified as long-term summerresidents, the remaining species being transientin nature. Thorny skate and monkfishdemonstrate greatly diminished frequencies ofoccurrence, and woiffish and white hake haveceased to be reported as summer residents inthe 1990-93 period.

Examining seasonal data from 1979-85,31 species were reported (Fig. 94). Of these,48% were considered year-round residehts, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer, with 81% of the speciesreported compared to 77% and 61 % in the springand fall, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with 8.8species, followed by 8.7 in the spring and 6.9 inthe summer (Table 4). Species stronglyinfluenced by season include redfish, argentine,wolffish and herring as spring/summer species.

Stratum 464: Western Bank

This stratum is found in depths of <50fath at the western end of Sable Island Bank, andoccupies an area of 1297 naut mi2, aboutaverage in area.

Sampling effort during summer surveysincreased from 5 to 7 stations per year in 1990,with a total of 126 stations fished successfully.This represented an average of 0.10 stations pernaut mi2, slightly below the average of 0.12stations per naut mi2 for all strata. The rate ofcapture of new species since 1984 was high at0.93 species per year, indicating that this stratumis not well sampled for species composition(Table 1, Fig. 7, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data was9.7±0.4, slightly above the average of 9.1 speciesfor all strata.

20

A total of 42 species have been reportedin this stratum from summer surveys, which isnear the average of 40 for all strata (Fig. 43). Ofthe 42 species reported from summer surveys,55% were classified as long-term summerresidents, the remaining species being transientin nature. Pollock appear to be increasing infrequency of occurrence, and wolffish appearsomewhat diminished in the 1990-93 period.

Examining seasonal data from 1979-85,40 species were reported ( Fig. 95). Of these,58% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer, with 83% of the speciesreported compared to 75% and 73% in the springand fall, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the summerand fall with 9.4 species, followed by 8.6 in thespring (Table 4). Species strongly influenced byseason include silver hake, witch, mackerel andwhite hake as summer/fall species.

Stratum 465: Emerald Mid-depths (south)

This stratum is found in depths of 51-100fath surrounding Emerald Bank, and occupies anarea of 2383 naut mi2, twice the area of anaverage stratum.

Sampling effort during summer surveysincreased from 5 to 10 stations per year by 1990,with a total of 152 stations fished successfully.This represents a sampling effort of 0.06 stationsper naut mi2, well below the average of 0.12stations per naut mi2 for all strata. The rate ofcapture of new species since 1984 was high at 1species per year, indicating that this stratum isnot well sampled for species composition (Table1, Fig. 7, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data was7.5±0.4, below the average of 9.1 species for allstrata.

A total of 50 species have been reportedin this stratum from summer surveys, which isabove the average of 40 for all strata (Fig. 44).Of the 50 species reported from summer surveys,50% were classified as long-term summer

residents, the remaining species being transientin nature. Thorny skate, cusk, smooth skate andwitch all demonstrate diminished frequencies ofoccurrence in the 1990-93 period.

Examining seasonal data from 1979-85,53 species were reported ( Fig. 96). Of these,45% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer, with 72% of the speciesreported compared to 66% and 70% in the springand fall, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with11.1 species, followed by 9.4 in the fall and 9.2in the summer (Table 4). Species stronglyinfluenced by season include mackerel andherring as spring/summer species, and alewivesas spring species.

Stratum 466: Scotian Shelf Edge (EmeraldArea)

This small stratum is found in depths>100 fath on the edge of the Scotian Shelf, andoccupies an area of only 226 naut miZ.

Sampling effort during summer surveysdecreased from 3 to 2 stations per year in 1989,with a total of 61 stations fished successfully.This represents a sampling effort of 0.27 stationsper naut mi2, well above the average of 0.12stations per naut miZ for all strata. The rate ofcapture of new species since 1984 was high at0.98 species per year, indicating that this stratumis not well sampled for species compositionregardless of high sampling effort (Table 1, Fig.7, 11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was 8.7±0.5,below the average of 9.1 species for all strata. •

A total of 48 species have been reportedin this stratum from summer surveys, which isabove the average of 40 for all strata (Fig. 45).Of the 48 species reported from summer surveys,40% were classified as long-term summerresidents, the remaining species being transientin nature. Thorny skate, marlin spike grenadiers,and lanternfish have all disappeared as summerresidents in the 1990-93 period. Smooth skate

21

demonstrates a diminished frequency ofoccurrence in the 1990-93 period. Pollock maybe potential immigrants as summer residents inthis stratum.

Examining seasonal data from 1979-85,60 species were reported ( Fig. 97). Of these,37% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 73% of the species reportedcompared to 63% and 58% in the spring andsummer, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with13.1 species, followed by 10.8 in the fall and 10.4in the summer (Table 4). Species stronglyinfluenced by season include halibut, ocean poutand longhorn sculpin as spring/summer species,and spiny dogfish as spring/fall species.

Examining seasonal data from 1979-85,37 species were reported ( Fig. 98). Of these,51% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the spring, with 81% of the species reportedcompared to 70% and 78% in the summer andfall, respectively (Table 5). The relative diversityby season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with13.4 species, followed by 13.1 in the fall and 12.9in the summer (Table 4). Species stronglyinfluenced by season include cusk, dogfish,herring and wolffish as spring/summer species.

Stratum 471: LaHave Basin

This stratum is found in depths >100 fathwest of Emerald Basin, and occupies an area of1004 naut miZ, about average in size.

Stratum 470: LaHave Coastal

This stratum is found in depths of 51-100fath north of LaHave Basin along coastal NovaScotia, and occupies an area of 920 naut miz,about average in area.

Sampling effort during summer surveyshas remained constant at 2 stations per year,with a total of 50 stations fished successfully.This represents a sampling effort of 0.05 stationsper naut mi2, below the average of 0.12 stationsper naut mi2 for all strata. The rate of capture ofnew species since 1984 was low at 0.48 speciesper year, indicating that this stratum is wellsampled for species composition (Table 1, Fig. 7,11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was 11.7±0.2,above the average of 9.1 species for all strata.

A total of 37 species have been reportedin this stratum from summer surveys, which isbelow the average of 40 for all strata (Fig. 46). Ofthe 37 species reported from summer surveys,54% were classified as long-term summerresidents, the remaining species being transientin nature. Wolffish and smooth skate have bothdisappeared as summer residents in the 1990-93period. Cusk demonstrates a diminishedfrequency of occurrence in the 1990-93 period.

Sampling effort during summer surveyshas remained constant at 2 stations per year,with a total of 48 stations fished successfully.This represents a sampling effort of 0.05 stationsper naut mi2, below the average of 0.12 stationsper naut mi2 for all strata. The rate of capture ofnew species since 1984 was low at 0.19 speciesper year, indicating that this stratum is very wellsampled for species composition (Table 1, Fig. 7,11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was 8.6±0.4,below the average of 9.1 species for all strata.

A total of 27 species have been reportedin this stratum from summer surveys, which iswell below the average of 40 for all strata (Fig.47). Of the 27 species reported from summersurveys, 59% were classified as long-termsummer residents, the remaining species beingtransient in nature. Haddock, smooth skate andlong-finned hake have all disappeared assummer residents in the 1990-93 period. Cuskand thorny skate both demonstrate diminishedfrequencies of occurrence in the 1990-93 period.

Examining seasonal data from 1979-85,34 species were reported (Fig. 99). Of these,59% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most species

22

was the spring, with 85% of the species reportedcompared to 74% and 82% in the summer andfall, respectively (Table 5). The relative diversityby season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the spring with12 species , followed by 10.9 in the fall and 10.7in the summer (Table 4). Species stronglyinfluenced by season include redfish and offshorehake as summer/fall species, and herring andalewives as spring species.

Stratum 472: LaHave mid-depths

This stratum is found in depths of 51-100fath south of LaHave Basin, and occupies anarea of 1249 naut mi2, about average in size.

Sampling effort during summer surveyswas increased from 2 to 4 stations per year in1989, with a total of 66 stations fishedsuccessfully. This represents a sampling effort of0.05 stations per naut mi2, below the average of0.12 stations per naut mi2 for all strata. The rateof capture of new species since 1984 was low at0.15 species per year, indicating that this stratumis very well sampled for species composition(Table 1, Fig. 7, 11). The diversity of the summercommunity as measured by the mean number ofspecies per tow from summer survey data was8.4+0.5, below the average of 9.1 species for allstrata.

A total of 35 species have been reportedin this stratum from summer surveys, which isbelow the average of 40 for all strata (Fig. 48). Ofthe 35 species reported from summer surveys,57% were classified as long-term summerresidents, the remaining species being transientin nature. Dogfish and smooth skate have bothdisappeared as summer residents in the 1990-93period. Thorny skate, wolffish, monkfish and witchall demonstrate diminished frequencies ofoccurrence in the 1990-93 period.

Examining seasonal data from 1979-85,45 species were reported (Fig. 100). Of these,53% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 76% of the species reportedcompared to 71% in the spring and summer(Table 5). The relative diversity by season from

seasonal survey data as measured by the meannumber of species captured per tow was greatestin the summer with 10 species , followed by 9.4in the fall and 9.3 in the spring (Table 4). Speciesstrongly influenced by season include argentine,longhorn sculpins, wotffish and black-belliedrosefish as summer/fall species, and alewives asspring species.

Stratum 473: LaHave Bank

This small stratum is found in depths of<50 fath south of LaHave Basin, and occupies anarea of only 265 naut mi2.

Sampling effort during summer surveyshas remained constant at 2 stations per year,with a total of 49 stations fished successfully.This represents a sampling eff ort of 0.19 stationsper naut mi2, above the average of 0.12 stationsper naut mi2 for all strata. The rate of capture ofnew species since 1984 was low at 0.16 speciesper year, indicating that this stratum is very wellsampled for species composition (Table 1, Fig. 8,11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was 4.6±0.3, thelowest value for all strata.

A total of only 22 species have been.reported in this stratum from summer surveys,which is the lowest number for all strata (Fig. 49).Of the 22 species reported from summer surveys,50% were classified as long-term summerresidents; the remaining species being transientin nature. Thorny skate and halibut havedisappeared as summer residents in the 1990-93period. Redfish and dogfish demonstratediminished frequencies of occurrence in the1990-93 period.

Examining seasonal data from 1979-85,36 species were reported ( Fig. 101). Of these,36% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 94% of the species reportedcompared to 53% and 44% in.the spring andsummer, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with 7species , followed by 5.7 in the spring and 5.4 in

23

the summer (Table 4). Species strongly influenced by season include thorny skate, pollock, smooth skate and dogfish as summer/fall species, silver hake as a fall species, and herring and lumpfish as spring/fall species.

Stratum 474: Roseway Bank

This small stratum is found in depths of <50 fath east of LaHave Basin, and occupies an area of only 161 naut mi 2 .

Sampling effort during summer surveys has remained constant at 2 stations per year, with a total of 46 stations fished successfully. This represents a sampling effort of 0.28 stations per naut mi2 , making this stratum one of the best sampled. The rate of capture of new species since 1984 was low at 0.46 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 8, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 5.9+0.4, far below the average of 9.1 for all strata.

A total of only 28 species have been repo rted in this stratum from summer surveys, significantly below the average of 40 for all strata (Fig. 50). Of the 28 species reported from summer surveys, 42% were classified as long-term summer residents, the remaining species being transient in nature. Halibut and longhorn sculpin have disappeared as summer residents in the 1990-93 period.

Examining seasonal data from 1979-85, 40 species were repo rted (Fig. 102). Of these, 45% were considered year-round residents, and the remainder were classified as seasonal species. The season repo rt ing the most species was the fall, with 93% of the species repo rted compared to 55% and 60% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the summer with 7.1 species , followed by 6.9 in the spring and 5.8 in the fall (Table 4). Species strongly influenced by season include dogfish and lumpfish as summer/fall species, and winter skate and sea raven as spring/fall species.

Stratum 475: Baccaro Bank

This small stratum is found in depths of <50 fath east of LaHave Bank, and occupies an area of only 156 naut mi 2 .

Sampling effort during summer surveys has remained constant at 2 stations per year, with a total of 48 stations fished successfully. This represents a sampling effort of 0.30 stations per naut mi2 , making this stratum one of the best sampled. The rate of capture of new species since 1984 was high at 0.85 species per year, indicating that this stratum is not well sampled for species composition (Table 1, Fig. 8, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 7.7+0.6, below the average of 9.1 for all strata.

A total of only 31 species have been reported in this stratum from summer surveys, well below the average of 40 for all strata (Fig. 51). Of the 31 species reported from summer su rveys, 55% were classified as long-term summer residents, the remaining species being transient in nature. Sea raven, smooth skate, cusk, witch, yellowtail and silver hake have all disappeared as summer residents in the 1990-93 period. Thorny skate, mailed sculpin and redfish are all indicating diminished frequencies of occurrence. Dogfish was a high frequency visitor in the 1982-89 period.

Examining seasonal data from 1979-85, 44 species were reported (Fig. 103). Of these, 52% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 91% species reported compared to 77% and 55% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 11.9 species, followed by 11 in the fall and 8.1 in the summer (Table 4). Species strongly influenced by season include pollock, silver hake and cusk as spring/fall species, dogfish as a summer/fall species, and white hake and alewives as fall species.

24

Stratum 476: Roseway mid-depths

This stratum is found in depths of 51-100 fath no rt h of Baccaro Bank, and occupies an area of 1478 naut mi2 , slightly larger than the mean stratum area.

Sampling effort during summer surveys was increased from 2 to 4 stations per year in 1987, with a total of 64 stations fished successfully. This represents a sampling effort of 0.04 stations per naut mi 2 , much lower than the mean of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was low at 0.57 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 8, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.9+0.5, above the average of 9.1 for all strata.

A total of 35 species have been reported in this stratum from summer surveys, below the average of 40 for all strata (Fig. 52). Of the 35 species reported from summer surveys, 60% were classified as long-term summer residents, the remaining species being transient in nature. The summertime community in this stratum appears to be very stable, as no great shifts in frequency of occurrence are evident, other than herring, which have increased dramatically in the 1990-93 period.

Examining seasonal data from 1979-85, 38 species were reported (Fig. 104). Of these, 66% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 90% species reported compared to 79% and 76% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 12.9 species, followed by 12.6 in the fall and 10.5 in the summer (Table 4). Species strongly influenced by season include dogfish as a summer/fall species, and mackerel as a fall species.

Stratum 477: Baccaro mid-depthS

This stratum is found in depths of 51-100 fath south of Baccaro Bank, and occupies an area of 1 232 naut m12 , about average in size.

Sampling effort during summer surveys was increased from 2 to 5 stations per year in 1990, with a total of 68 stations fished successfully. This represents a sampling effort of 0.06 stations per naut mi2, much lower than the mean of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was 0.75 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 8, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 7.8+0.5, below the average of 9.1 for all strata.

A total of 35 species have been reported in this stratum from summer surveys, below the average of 40 for all strata (Fig. 53). Of the 35 species reported from summer surveys, 63% were classified as long-term summer residents, the remaining species being transient in nature. Smooth skate have disappeared as summer residents in the 1990-93 period. Thorny skate, cusk and wolffish are all indicating diminished frequencies of occurrence. Dogfish was a high frequency visitor in the 1982-89 period. The frequency of occurrence of pollock has increased dramatically in this stratum.

Examining seasonal data from 1979-85, 39 species were reported (Fig. 105). Of these, 64% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the fall, with 82% species reported compared to 74% and 77% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal su rvey data as measured • by the mean number of species captured per tow was greatest in the spring and fall with 11.6 species, followed by 8.7 in the summer (Table 4). Species strongly influenced by season include pollock as a spring/summer species, and herring and alewives as spring species.

25

Stratum 478: Scotian Shelf Edge (Baccaro-LaHave Area)

This small stratum is found in depths>100 fath along the edge of the Scotian Shelfwest of stratum 466, and occupies an area of233 naut mi2.

Sampling effort during summer surveysdecreased from 3 to 2 stations per year in 1987,with a total of 62 stations fished successfully.This represents a sampling effort of 0.27 stationsper naut mi2; one of the highest samplingintensities of all strata. The rate of capture of newspecies since 1984 was 0.72 species per year,indicating that this stratum is adequately sampledfor species composition (Table 1, Fig. 8, 11). Thediversity of the summer community as measuredby the mean number of species per tow fromsummer survey data was 10.1±0.3, above theaverage of 9.1 for all strata.

A total of 52 species have been reportedin this stratum from summer surveys, well abovethe average of 40 for all strata (Fig. 54). The rateof capture of new species in this stratum hasstarted to diminish, but averages about 1 speciesper year since 1984. Of the 52 species reportedfrom summer surveys, 40% were classified aslong-term summer residents, the remainingspecies being transient in nature. Offshore hakehave disappeared as summer residents in the1990-93 period.Witch and monkfish are bothindicating diminished frequencies of occurrence.Smooth skate was once a high frequency visitorin previous periods, but has not been reportedsince the 1982-85 period. The frequency ofoccurrence of red hake has increaseddramatically in this stratum.

Examining seasonal data from 1979-85,65 species were reported (Fig. 106). Of these,40% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 72% of the species reportedcompared to 52% and 71% in the spring andsummer, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with13.1 species, followed by 12.6 in the spring, and11.9 in the summer (Table 4). Species strongly

influenced by season include dogfish andalewives as spring species, halibut as a summerspecies, and lanternfishes as summer/fallspecies.

Stratum 480: Browns Bank

This stratum is found in depths < 50 fathwest of Baccaro Bank, and occupies an area of655 naut mi2, about half the size of an averagestratum.

Sampling effort during summer surveysincreased from 4 to 8 stations per year by 1990,with a total of 104 stations fished successfully.This represents a sampling effort of 0.16 stationsper naut miZ ; above the average of 0.12 stationsper naut mi2 for all strata. The rate of capture ofnew species since 1984 was low at 0.33'speciesper year, indicating that this stratum is wellsampled for species composition (Table 1, Fig. 9,11). The diversity of the summer community asmeasured by the mean number of species pertow from summer survey data was 8.0±0.3,below the average of 9.1 for all strata.

A total of 37 species have been reportedin this stratum from summer surveys, below theaverage of 40 for all strata (Fig. 55). Of the 37species reported from summer surveys, 57%were classified as long-term summer residents,the remaining species being transient in nature.Cusk have disappeared as summer residents inthe 1990-93 period. Thorny skate and dogfish areboth indicating diminished frequencies ofoccurrence.

Examining seasonal data from 1979-85,40 species were reported ( Fig. 107). Of these,50% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the fall, with 80% of the species reportedcompared to 65% and 75% in the spring andsummer, respectively (Table 5). The relativediversity by season from seasonal survey data asmeasured by the mean number of speciescaptured per tow was greatest in the fall with 10species, followed by 9.2 in the summer, and 9 inthe spring (Table 4). Species strongly influencedby season include dogfish and silver hake as

26

summer/fall species, and herring and lumpfish as spring species.

Stratum 481: Brown's Bank mid-depths

This stratum is found in depths of 51-100 fath surrounding Brown's Bank, and occupies an area of 1875 naut mi2 .

Sampling effort during summer surveys increased from 4 to 9 stations per year by 1990, with a total of 121 stations fished successfully. This represents a sampling effort of 0.07 stations per naut mi2 ; above the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was 0.76 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 9, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 9.0+0.4, the average for all strata.

A total of 45 species have been reported in this stratum from summer su rveys, above the average of 40 for all strata (Fig. 56). Of the 37 species reported from summer surveys, 62% were classified as long-term summer residents, the remaining species being transient in nature. Cusk is indicating a slightly diminished frequency of occurrence, and herring are appearing more frequently, but the overall state of the community in this stratum appears to be very stable.

Examining seasonal data from 1979-85, 46 species were reported (Fig. 108). Of these, 65% were considered year-round residents, and the remainder were classified as seasonal species. The seasons reporting the most species was the spring and fall with 80% of the species reported compared to 78% in the summer (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 11.3 species, followed by 10.8 in the spring, and 10.2 in the summer (Table 4). No species of high frequency are dramatically affected by season in this stratum.

Stratum 482: FundIan Channel

This stratum is found in depths >100 fath along the eastern contour of the Fundian

Channel, and oc,cupies an area of 1042 naut re the average size for a stratum.

Sampling effort during summer surveys increased from 2 to stations per year by 1989, with a total of 56 stations fished successfully. This represents a sampling effort of 0.05 stations per naut mi2 ; below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was high at 0.98 species per year, indicating that this stratum is not well sampled for species composition (Table 1, Fig. 9, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 8.4+0.4, below the average of 9.1 for all strata.

A total of 36 species have been reported in this stratum from summer surveys, below the average of 40 for all strata (Fig. 57). Of the 36 species reported from summer surveys, 47% were classified as long-term summer residents, the remaining species being transient in nature. Monkfish has ceased to be reported as a summer resident in the 1990-93 period. Smooth skate indicates a diminished frequency of occurrence. Black bellied rosefish may appear to have increased frequency of occurrence, but this may be a consequence of increased diligence by samplers in separating them from redfish catches.

Examining seasonal data from 1979-85, 39 species were reported (Fig. 109). Of these, 46% were considered year-round residents, and the remainder were classified as seasonal species. Spring was the season with the most species repo rted, with 77% compared to 69% being reported in both the summer and fall (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the . spring with 11.1 species, followed by 10.7 in the fall, and 10.2 in the summer (Table 4). Species strongly influenced by season include alewives, red hake and mackerel as spring/summer species, and longhorn sculpin, yellowtail and little skate as spring/fall species.

27

Stratum 483: Georges Basin

This stratum is found in depths >100 fath no rt h of Georges Bank, and occupies an area of 532 naut mi 2 , about half the size of an average stratum.

Sampling effort during summer surveys has remained constant at 2 stations per year, with a total of 47 stations fished successfully. This represents a sampling effort of 0.09 stations per naut mi2 , below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was 0.53 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 9, 11). The diversity of the summer community as measured by the mean number of species per tow from sumrrier survey data was 10.2+0.4, above the average of 9.1 for all strata.

Stratum 484: Crowell and Jordan Basins

This stratum is found in depths >100 fath in the Gulf of Maine, and occupies an area of 2264 naut mi2 , about twice the area of an average stratum.

Sampling effort during summer surveys has remained constant at 3 stations per year, with a total of 73 stations fished successfully. This represents a sampling effort of 0.03 stations per naut mi 2 , far below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was high at 0.99 species per year, indicating that this stratum is not well sampled for species composition (Table 1, Fig. 9, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 10.3+0.3, above the average of 9.1 for all strata.

A total of 34 species have been reported in this stratum from summer surveys, below the average of 40 for all strata (Fig. 58). Of the 34 species reported from summer surveys, 50% were classified as long-term summer residents, the remaining species being transient in nature. Cod indicates a diminished frequency of occurrence for the 1990-93 period. Otherwise, the summertime community in this stratum appears to be very stable.

Examining seasonal data from 1979-85, 39 species were reported (Fig. 110). Of these, 41% were considered year-round residents, and the remainder were classified as seasonal species. Summer was the season with the most species reported, with 69% compared to 64% and 59% in the spring and fall, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the summer with 12.2 species, followed by 11.1 in the spring, and 10.7 in the fall (Table 4). Species strongly influenced by season include haddock, cod and plaice as summer/fall species, pollock and monkfish as spring/summer species, and herring as a spring/fall species.

A total of 40 species have been reported in this stratum from summer surveys, about the average for all strata (Fig. 59). Of the 40 species reported from summer surveys, 50% were classified as long-term summer residents, the remaining species being transient in nature. Cod indicates a diminished frequency of occurrence for the 1990-93 period, and herring and alewives have increased in frequency of occurrence. Otherwise, the summertime community in this stratum appears to be very stable.

Examining seasonal data from 1979-85, 42 species were reported (Fig. 111). Of these, 47% were considered year-round residents, and the remainder were classified as seasonal species. Spring was the season with the most species reported, with 86% compared to 67% and 64% for the summer and fall, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 13.0 species, followed by 12.2 in the fall, and 11.3 in the summer (Table 4). Species strongly influenced by season include shad as a spring/summer species, and longf in hake as a fall species.

28

Stratum 485: Gulf of Maine (mid-depths)

This stratum is found in depths of 51-100 fath in the Gulf of Maine, and occupies an area of 1582 naut mi 2 .

Sampling effort during summer surveys has remained constant at 3 stations per year, except during the 1987-89 period when 6 stations were fished per year, with a total of 78 stations fished successfully. This represents a sampling effort of 0.05 stations per naut mi2 , far below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was 0.69 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 9, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 11.5+0.4, above the average of 9.1 for all strata.

A total of 41 species have been reported in this stratum from summer surveys, about the average for all strata (Fig. 60). Of the 41 species reported from summer surveys, 59% were classified as long-term summer residents, the remaining species being transient in nature. Smooth skate have ceased to be reported as summer residents in the 1990-93 period. Cusk and witch indicated diminished frequencies of occurrence for the 1990-93 period, and ocean pout, sea raven, winter flounder and yellowtail all have increased in frequencies of occurrence.

Examining seasonal data from 1979-85, 47 species were reported (Fig. 112). Of these, 58% were considered year-round residents, and the remainder were classified as seasonal species. All seasons for this stratum reported 77% of the species present Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 15.2 species, followed by 13.9 in the spring, and 13.6 in the summer (Table 4). Species strongly influenced by season include monkfish and yellowtail as spring/summer species.

Stratum 490: Outer Bay of Fundy (south)

This stratum is found in depths of < 50 fath along the northwestern Nova Scotia shore at

the mouth of the Bay of Fundy, and occupies an area of 601 naut mi2 .

Sampling effort during summer surveys has remained constant at 3 stations per year until 1989 when 4 stations were introduced, with a total of 73 stations fished successfully. This represents a sampling effort of 0.12 stations per naut mi2 , the average for all strata. The rate of capture of new species since 1984 was 0 species per year, indicating that this stratum is extremely well sampled for species composition (Table 1, Fig. 10, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 14.0+0.5, the highest reported for all strata.

A total of 42 species have been reported in this stratum from summer surveys,• slightly above the average for all strata (Fig. 61). Of the 42 species reported from summer surveys, 74% were classified as long-term summer residents, the remaining species being transient in nature. No dramatic shifts in the frequency of occurrence of species in this stratum are evident. This summer community is clearly very stable with no immigrants or emigrants, and very diverse with many residents at a high frequency of occurrence.

Examining seasonal data from 1979-85, 48 species were reported (Fig. 113). Of these, 54% were considered year-round residents, and the remainder were classified as seasonal species. All seasons for this stratum exhibited similar species compliments with 81% of the species reported in the summer, 79% in the fall and 77% in the spring (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 16.9 species, followed by 15.7 in the summer, and 13.1 in the spring (Table 4). Species • strongly influenced by season include haddock, white hake, silver hake, alewives, dogfish, red hake, littleskate, monkfish, butterfish, mackerel and shad as summer/fall species.

Stratum 491: Outer Bay of Fundy (central)

This stratum is found in depths 01 51-100 fath between Digby Neck and Grand Manan

Island, and occupies an area of 687 naut mi2.

29

Sampling effort during summer surveys has remained constant at 3 stations per year , with a total of 73 stations fished successfully. This represents a sampling effort of 0.11 stations per naut mi2 , slightly below the average for all strata. The rate of capture of new species since 1984 was 0.39 species per year, indicating that this stratum is extremely well sampled for species composition (Table 1, Fig. 10, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 12.2+0.5, one of the highest reported for all strata.

A total of 40 species have been reported in this stratum from summer surveys; the average for all strata (Fig. (62). Of the 40 species repo rted from summer surveys, 65% were classified as long-term summer residents, the remaining species being transient in nature. No dramatic shifts in the frequency of occurrence of species in this stratum are evident. This summer community is clearly very stable with no immigrants or emigrants,and very diverse with many residents at a high frequency of occurrence.

Examining seasonal data from 1979-85, 45 species were reported (Fig. 114). Of these, 60% were considered year-round residents, and the remainder were classified as seasonal species. The season repo rt ing the most species was the fall with 89% of the species, and 76% and 73% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 14.8 species, followed by 13.6 in the summer, and 13.3 in the spring (Table 4). Species strongly influenced by season include white hake, silver hake, dogfish, arctic hookeared sculpins, shad, hagfish and monkfish as summer/fall species, and halibut as a spring/fall species.

Stratum 492: Grand Manan mid-depths

This stratum is found in depths of 51-100 fath extending from the northeast to southwest of Grand Manan Island in the Bay of Fundy, and occupies an area of 1086 naut mi2 , about average in size.

Sampling effort during summer surveys has remained constant at 3 stations per year, with a total of 75 stations fished successfully. This represents a sampling effort of 0.07 stations per naut mi2, below the average of 0.12 stations per naut mi2 for all strata. The rate of capture of new species since 1984 was 0.5 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 10, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 11.5+0.4, the sixth highest repo rted for all strata.

A total of 44 species have been repo rted in this stratum from summer surveys, slightly above the average for all strata (Fig. 63). Of the 44 species reported from summer surveys, 56% were classified as long-term summer residents, the remaining species being transient in nature. Hagfish and wolffish have ceased to be represented as summer residents in the 1990-93 period. Haddock, smooth skate and cusk also demonstrate di mi nis hed f requ e nci es of occurrence. Otherwise, the community in this stratum appears to be very diverse and stable.

Examining seasonal data from 1979-85, 43 species were reported (Fig. 115). Of these, 65% were considered year-round residents, and the remainder were classified as seasonal species. The season with the most species was the fall with 91% of the species reported, and 79% and 77% in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the spring with 14.9 species, followed by 14.7 in the fall, and 11.7 in the summer (Table 4). Species strongly influenced by season include dogfish, shad and hagfish as summer/fall species, halibut as a spring species, and hookeared sculpin, butterfish and mackerel - as fall species.

Stratum 493: Grand Manan Channel, coastal New Brunswick.

This stratum is found in depths of < 50 fath extending from the Grand Manan Channel to Saint John along the southwestern coast of New Brunswick, and occupies an area of 533 naut mi2.

30

Sampling effort during summer surveys has remained constant at 3 stations per year, with a total of 67 stations fished successfully. This represents a sampling effort of 0.13 stations per naut mi2 , about the average for all strata. The rate of capture of new species since 1984 was 0.66 species per year, indicating that this stratum is adequately sampled for species composition (Table 1, Fig. 10, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 12.2+0.4, well above the average of 9.1 species reported for all strata.

A total of 46 species have been repo rted in this stratum from summer surveys, above the average of 40 for all strata (Fig. 64). Of the 46 species reported from summer surveys, 55% were classified as long-term summer residents, the remaining species being transient in nature. Haddock, witch and smooth skate demonstrate diminished frequencies of occurrence in the 1990-93 period. Otherwise, the community in this stratum appears to be very diverse and stable.

Examining seasonal data from 1979-85, 49 species were reported (Fig. 116). Of these, 51% were considered year-round residents, and the remainder were classified as seasonal species. The season with the most species was the fall with 88% of the species reported, and 61% and 78% reported in the spring and summer, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 17.1 species, followed by 13 in the spring, and 12.8 in the summer (Table 4). Species strongly influenced by season include white hake, silver hake, dogfish, haddock, butterfish, shad, monkfish and hagfish as summer/fall species, and winter skate, yellowtail and windowpane as spring/fall species.

Stratum 494: Inner Bay of Fundy (north)

This small stratum is found in depths of < 50 fath extending from Saint John along the coast of New Brunswick to the entrance of Chignecto Bay, and occupies an area of 417 naut

.

M2i .

Sampling effort during summer surveys has remained constant at 2 stations per year, with a total of 49 stations fished successfully. This represents a sampling effort of 0.12 stations per naut mi2 , the average for all strata. The rate of capture of new species since 1984 was 0.49 species per year, indicating that this stratum is well sampled for species composition (Table 1, Fig. 10, 11). The diversity of the summer community as measured by the mean number of species per tow from summer survey data was 11.2+0.5, well above the average of 9.1 species reported for all strata.

A total of 40 species have been reported in this stratum from summer surveys, the average for all strata (Fig. 65). Of the 40 species reported from summer surveys, 58% were classified as long-term summer residents, the remaining species being transient in nature. Witch, halibut, smelt, and smooth skate have all ceased to be reported as summer residents in this stratum. Haddock and thorny skate demonstrate diminished frequencies of occurrence in the 1990-93 period.

Examining seasonal data from 1979-85, 44 species were reported (Fig. 117). Of these, 30% were considered year-round residents, and the remainder were classified as seasonal species. The season reporting the most species was the summer with 77% of the species reported, and 52% and 59% reported in the spring and fall, respectively (Table 5). The relative diversity by season from seasonal survey data as measured by the mean number of species captured per tow was greatest in the fall with 12.3 species, followed by 12.1 in the summer, and 10.6 in the spring (Table 4). Species strongly influenced by season include dogfish, white hake, silver hake, haddock, red hake, butterfish and shad as summer/fall species, windowpane as spring/fall species, smooth skate • as a spring/summer species, and pollock and witch as summer species.

Stratum 495: Inner Bay of Fundy (south)

This stratum is found in depths of < 50 fath extending from Digby along the coast of Nova Scotia to the entrance of the Minas Channel, and occupies an area of 584 naut mi2 , about half the size of an average stratum.

31

Sampling effort during summer surveyshas remained constant at about 2 stations peryear, with a total of 47 stations fishedsuccessfully. This represents a sampling effort of0.08 stations per naut mi2, below the average forall strata. The rate of capture of new speciessince 1984 was 0.65 species per year, indicatingthat this stratum is adequately sampled forspecies composition (Table 1, Fig. 10, 11). Thediversity of the summer community as measuredby the mean number of species per tow fromsummer survey data was 9.9±0.4, slightly abovethe average of 9.1 species reported for all stratacombined.

A total of 36 species have been reportedin this stratum from summer surveys, below theaverage of 40 for all strata ( Fig. 66). Of the 36species reported from summer surveys, 53%were classified as long-term summer residents,the remaining species being transient in nature.Pollock have ceased to be reported as a residentin this stratum. Haddock demonstrate adiminished frequency of occurrence in the 1990-93 period.

Examining seasonal data from 1979-85,43 species were reported (Fig. 118). Of these,40% were considered year-round residents, andthe remainder were classified as seasonalspecies. The season reporting the most specieswas the summer with 70% of the speciesreported, and 67% reported in both spring andfall (Table 5). The relative diversity by seasonfrom seasonal survey data as measured by themean number of species captured per tow wasgreatest in the fall with 14.5 species, followed by11.9 in the spring, and 11.2 in the summer (Table4). Species strongly influenced by season includehaddock, dogfish, white hake, silver hake andbuttertish as summer/fall species, windowpane asspring/fall species, smooth skate and snakeblennies as a spring/summer species, and shadand mailed sculpin as fall species.

DISCUSSION

EFFECTS OF SAMPLING INTENSITY ANDGEAR PERFORMANCE

It should be recognised that the bottomtrawl surveys were designed primarily to provide

data for the assessment of the abundance ofcommercially important species, particularly cod,haddock and pollock. Consequently, a positivebias in the station selection occurs in stratawhere these species are abundant. Conclusionsabout the relative diversity of the offshore areasdelimited by the sampling strata, were not madewithout first examining which areas have beenadequately sampled. One measure of relativesampling effort, the stations per naut mi2, rangedfrom 0.04-0.32. Typically, the better sampledstrata were smaller in area with a default of twostations sampled yearly, or larger with manystations. However, the strata with the moststations per unit area were not always adequatelysampled to provide an accurate assessment ofthe species composition and the frequencies ofoccurrence of the species reported. This effect islikely a consequence of the relative size anduniformity of the environments found in eachstratum. Large strata with a great range ofbottom types, bathymetry and hydrography havebigger potential to host more community types,and would require a sampling program withgreater resolution. Also related to the lack ofuniformity in a sampling environment is theassociated variance in the performance of thesampling gear. Trawl performance is verysensitive to changes in bottom composition,grade, depth and currents (Strong 1992), as isthe affinity for certain species for these factors.The range in bottom types and bathymetry foundin the Scotia-Fundy Region, and the variance incatch associated with trawl behavior was found toimpact on survey estimates (Clark 1993).Consequently, the reader is cautioned that thespecies described represent only a subset of theactual species compliment, those vulnerable tocapture by the gear types used.

The change in fishing vessels, crews andtrawls in 1982 may have impacted on theassessment of species composition and thefrequency at which each species was captureddue to differences in vessel horsepower, fishingmethods and selectivity between the trawls.Although depth induced variance in gear spreadwas minimized during the use of the Yankee 36trawl on the "A.T. Cameron" by observing warp todepth ratios designed to render constant spreadwith depth, a constant scope of 3 to 1 on latersurveys was observed with the Western IIAresulting in greater spreads and a lower headline

32

height for deeper tows (Strong 1992). Considering the above factors, the overall trend in the mean number of species per tow (Fig. 18) may be a vessel effect. The "Cameron" detected fewer species than the Needier and perhaps not the species that affect change in mspt. The declining trend in mspt after 1981 suggests that the Needier may have witnessed a shift in mspt due to some biological or physical processes. It is entirely possible , yet unlikely, that a massive shift in species diversity occurred in the same year as a complete change in vessel and sampling gear.

FACTORS RELATED TO DIVERSITY

Total species inventory

Certain elements appear to be characteristic of high and low diversity areas. High diversity strata clearly have a high total compliment of species, a high proportion of which demonstrate a high frequency of occurrence, which translates into a high number of species captured per tow relative to other strata. Low diversity strata are similarly low in these measures. However, all remaining strata do not fall between these extremes in a linear sense, as some areas will have a high species compliment with very few species of high frequency, and others may have low total species compliment with enough high frequency species to be of relatively high diversity. The distribution of strata relative to total species and mean species captured per tow from summer data are depicted in Fig. 67.

Seasonality

Seasonal change was a significant factor affecting diversity in many strata. The frequency of occurrence for species subject to migratory trends was impacted, translating into a change in the number of species observed per tow. The range in for all strata was a change of zero to four species per tow between seasons, where the strata exhibiting the greatest diversity were the most profoundly affected by change in season. Seasonal visitation was an important factor in making the Fundy and Gully area strata highly diverse in the fall season (Fig. 119).

Exploitation by commercial fishing

The impact of bottom trawling and other gear types on species diversity is an important consideration in fisheries management. Heavy bottom-trawling effort might make the benthic habitat less habitable and lower the survival rates of a wide range of species, thus lowering diversity from pre-exploitation levels. Alternately, selective removal of market sized fish of the commercially valuable species might increase diversity by reducing predation pressure on smaller, low frequency prey species, which would also tend to escape and survive from commercial gear. The frequency of occurrence for these secondary species would then increase enhancing diversity. To test these hypotheses, trends of diversity in regions of known fishing effort would have to be examined for changes with time.

Hydrography, bathymetry and geographic locale

Generally, the most diverse strata were found in the western region, where bottom temperatures enjoy a higher yearly mean, and are relatively moderate in annual amplitude. From the examination of the contour plots of diversity by season, one will note that high diversity areas generally shift seasonally away from the shallow bank areas to deeper locations such as basins or canyons along the shelf in the spring. By the fall, the deep water concentrations have dispersed, and new large aggregations of species form in the shallow coastal areas. Given that deeper areas in the spring provide warmer and more saline water than do the shallower regions, it might be surmised that a greater number of species prefer milder conditions, and migrate accordingly. The aggregations of species in the slope strata in the spring best illustrates this scenario.

The diminishing trends in the frequencies of occurrence of the 31 species identified in this study may in time impact upon the diversity of some strata. Examining a time series of summer strata mean temperature anomalies, where the anomalies were calculated as deviations from long-term (1970-92) strata means (Page et al. 1994), the majority of strata are below their means in recent years. However, in order to

33

relate large shifts in the frequencies ofoccurrence of the species identified in this studyto changing hydrographic conditions, thetemperature preferences of all species must beassessed and compared to the summer bottomtemperatures per stratum (Page et al. 1994).

The geographic location of each stratumappears to be of great influence in the level ofdiversity found, as many important factors are aconsequence of location. These factors wouldinclude the proximity of the stratum to coastalinfluences like islands, river systems, bays,estuaries, salt marshes and consequently, all theassociated fauna from these inshore sources.The Bay of Fundy strata are influenced by manyof these features, and not surprisingly, are themost diverse.

succeed in minimizing high by-catches, or if by-catches remained too high, such a fishery couldbe limited to gear types more selective to herring.

A mufti-species management approachshould be applied in areas where non-finfishpopulations congregate, such as in the case ofmigratory marine mammals and sea birds whichfeed on finfish. Considering that traditionalresource management methods are currentlyunder review, it is anticipated that a moreecological approach to resource management willbe adopted, and that a broader range of marinespecies be considered in the managementstrategy.

CONCLUSIONS

IMPLICATIONS FOR RESOURCEMANAGEMENT

The exercise of elucidating spatial andtemporal windows of high biodiversity iswarranted for several reasons. Ideally, suchwindows need to be identified before a multi-species approach to resource management canbe employed as an alternative to the "stock bystock" method that is currently used forcommercial fisheries.

Fundamentally, the more complex thecommunity structure found at a given place andtime, the greater the problem to design a harveststrategy for the exploitation of a single specieswithout impacting on others. It is thereforedesirable to identify the times and areasdemonstrating the highest diversity for the mostcareful harvest strategies.

As an example from this study, the Bayof Fundy strata demonstrate high diversity in thefall, which results in part from seasonalmigrations of anadromous species visiting therivers and estuaries surrounding the bay. If theimplementation of a herring fishery using seinegear were to be considered, the impact on othercommercially valuable species vulnerable tocapture by this gear type should first beassessed. As the species in this case wouldinclude alewives, Atlantic salmon, smelt andshad, altering the time and area windows might

The most diverse finfish communities inthe Scotia-Fundy Region are found in the fallseason, and primarily in the Bay of Fundy. Thelowest diversity is usually found in the spring inthe shallow bank areas. Spatial patterns of highdiversity have been found to shift with time, butremain the most persistent in the Bay of FundyRegion.

The species composition of strata varygreatly in character in terms of the number ofspecies reported, the frequency with which eachspecies is reported, and in the stability of thecommunities in terms of the number of seasonaland year-round species. Long-term shifts in thefrequency of occurrence of many species weredetected in this study, in some cases for groupsof strata in common, and an investigation of thecausal mechanisms is warranted.

The use of assessments of speciesdiversity as a fisheries management tool may bevaluable in avoiding the undesired exploitation ofspecies that share the same time and space asthe target fishery.

ACKNOWLEDGMENTS

We wish to thank Fred Page and DonClark for their support, and for the many endlessdiscussions which generated the ideas andmotivation for this study.

34

REFERENCES

Black, G. A. P. 1993. Acon Data Visualization Software User Manual. Version 7.14.MS: 232 p.

Clark, D. S. 1993, The influence on depth and bottom type on area swept by groundtrawl, and consequences for survey indices and population estimates. DFO Atl. Fish. Res. Doc. 93/40.

Doubleday, W. G., and D. Rivard. 1981. Bottom trawl surveys. Can. Spec, Publ. Fish. Aquat. Sci. 58.

Page, F. H., R. J. Losier, and J. McRuer. 1994. Overview of 1993 temperature and salinity conditions within the Scotia-

Fundy Region, NAFO areas 4VWX and 5Z, during groundfish research vessel surveys. DFO Atl. Fish. Res. Doc. 94/44.

Pielou, E. C. 1969. An introduction to mathematical ecology. Wiley- Interscience, Toronto.

Strong, M. B. 1992. Variability of trawl performance on Scotia-Fundy research surveys. Can. Atl. Fish. Sci. Advis. Comm. Res. Doc. 92/58.

Tukey, J. W. 1977. Exploratory Data Analysis. Addison-Wesley, Reading MA.

Watson, D. F., and G. M. Philip. 1985. A refinement of inverse distance weighted interpolation. Geo-Processing 2: 315- 327

35

Table 1. Summary of summer survey results by stratum.

Str Area innaut mi2

Stations pernaut mi2

Mean no. ofspecies per tow

Total no. ofspecies

Percent of specieslong-term residents

New species peryear since 1984

440 924 0.089 9.6 53 34 1.12441 1000 0.085 9.1 49 43 1.28442 1437 0.061 5.6 48 35 1.43443 1318 0.069 5.6 35 46 0.38444 3925 0.032 7.5 54 43 1.54445 1023 0.097 9.1 57 40 1.25446 491 0.143 10.4 49 43 0.79447 1616 0.075 7.3 32 50 0.65448 1449 0.079 6.9 36 45 0.88449 144 0.326 6.1 24 58 0.15450 383 0.180 8.2 36 50 0.61451 147 0.320 9.9 39 46 0.75452 345 0.154 11.7 45 49 1.10453 259 0.247 9.2 45 47 0.22454 499 0.128 7.8 37 46 0.67455 2122 0.085 9.5 35 69 0.53456 955 0.153 9.6 43 63 0.95457 811 0.067 8.3 40 48 0.82458 658 0.147 7.4 34 57 0.74459 3147 0.033 9.9 50 66 0.48460 1344 0.042 10.3 40 55 1.01461 1154 0.043 9.0 30 50 0.33462 2116 0.047 10.0 39 62 0.72463 302 0.166 7.7 32 63 0.20464 1297 0.097 9.7 42 55 0.93465 2383 0.064 7.5 50 50 1.00466 226 0.270 8.7 48 40 0.98470 920 0.054 11.7 37 54 0.63471 1004 0.048 8.6 27 59 0.19472 1249 0.053 8.4 35 57 0.15473 265 0.185 4.5 22 50 0.16474 161 0.286 5.9 28 42 0.46475 156 0.308 7.7 31 55 0.85476 1478 0.043 9.9 35 60 0.57477 1232 0.055 7.8 35 63 0.75478 233 0.266 10.1 52 40 0.72480 655 0.159 8.0 37 57 0.33481 1875 0.066 9.0 45 62 0.76482 1042 0.054 8.4 36 47 0.98483 532 0.088 10.2 34 50 0.53484 2264 0.032 10.3 40 47 0.99485 1582 0.049 11.5 41 59 0.69490 601 0.122 14.0 42 54 0.00491 687 0.106 12.2 40 65 0.39492 1086 0.069 11.5 44 56 0.50493 533 0.126 12.2 46 55 0.66494 417 0.118 11.2 40 58 0.4949511 584 0.081 9.9 36 53 0.65

-11

36

Table 2: The number of tows (A), mean species per tow (B) and number of distinct species captured (C) in each stratum (Str) for each of six 4-yr time periods.

1970-73 1974-77 1978-81 1982-85 1986-89 1990-93

StrA B CA BCA B CA BCA BCA BC

440 11 10.36 24 12 9.00 21 12 9.75 25 13 10.38 30 20 10.20 28 15 11.40 37 441 11 9.36 27 10 8.00 20 12 9.00 29 14 10.00 30 17 10.59 29 21 10.67 37 442 9 5.89 19 11 4.82 18 12 5.33 22 12 6.58 31 23 6.57 27 21 7.14 37 443 14 6.43 20 14 6.36 22 15 5.67 20 17 6.18 20 18 5.50 18 13 5.38 26 444 14 8.14 23 23 8.39 31 17 6.29 23 19 8.42 34 22 7.64 31 32 9.22 39 445 16 9.56 29 14 9.71 30 17 8.06 26 17 9.53 36 18 11.00 41 17 11.35 40 446 10 10.20 26 12 9.25 22 12 10.08 27 13 12.23 38 12 11.75 33 11 12.55 31 447 17 7.59 24 18 8.61 23 17 6.94 21 16 8.25 16 24 6.96 20 29 7.14 21 448 16 8.44 25 17 7.47 21 18 7.22 21 16 7.88 21 20 6.40 19 28 6.43 23 449 8 8.88 19 9 6.00 17 7 6.57 14 7 6.29 15 8 5.38 14 8 6.00 17 450 9 7.89 23 12 9.75 22 12 8.50 23 12 8.58 25 12 9.33 25 12 9.92 28 451 7 10.86 22 8 9.38 22 9 8.11 24 8 11.63 25 8 12.00 25 7 11.14 23 452 8 9.13 25 8 11.75 25 10 12.70 29 8 11.88 32 9 14.89 31 10 14.20 35 453 10 9.30 21 12 10.00 29 12 10.92 34 12 10.33 32 9 10.00 26 9 10.44 30 454 11 8.64 24 12 8.67 26 11 8.82 21 12 7.83 25 9 10.33 26 9 8.22 20 455 26 9.46 27 26 10.38 27 28 10.18 23 29 10.83 29 30 9.57 29 41 9.71 32 456 20 9.45 29 21 10.76 25 25 10.16 37 23 9.57 34 25 10.72 32 32 10.31 41 457 8 10.13. 30 9 6.89 19 9 7.00 21 8 9.50 24 10 9.90 30 10 11.10 32 458 12 7.58 22 12 8.08 22 12 7.83 19 12 8.58 22 16 6.63 23 33 7.70 32 459 13 9.69 32 16 10.06 33 16 9.56 33 17 10.88 41 22 12.18 46 20 10.40 37 460 8 9.75 22 7 10.29 21 8 8.75 20 8 14.00 29 13 12.31 31 12 11.08 28 461 9 9.22 17 8 7.75 18 8 9.88 23 8 12.25 24 10 10.50 24 7 9.43 19 462 13 10.00 24 16 9.63 26 18 10.61 27 16 12.00 34 19 11.63 33 18 11.39 30 463 8 9.75 22 8 7.50 16 8 7.00 19 9 8.00 25 8 8.25 24 9 8.22 21 464 15 10.27 25 19 10.32 23 20 9.20 26 19 9.53 29 23 10.26 28 30 11.33 33 465 20 7.40 26 19 8.32 24 22 10.50 37 21 8.05 32 29 8.93 35 41 7.66 33 466 9 8.11 21 12 9.50 28 11 9.00 33 12 11.33 29 9 10.44 26 8 9.88 29 470 7 13.00 23 9 12.33 24 8 12.13 22 8 13.00 27 10 12.10 28 8 11.38 23 471 8 7.88 18 8 8.88 17 8 8.50 18 8 12.13 24 8 9.75 21 8 8.63 19 472 8 8.38 17 8 10.38 21 9 8.33 25 8 11.88 29 15 8.40 26 18 7.33 26 473 8 4.38 12 8 5.13 11 8 6.25 14 8 5.38 17 8 4.63 11 9 3.89 15 474 8 7.50 19 8 5.63 15 8 6.00 14 6 7.83 19 8 6.75 18 8 4.63 13 475 8 5.88 15 8 10.13 20 8 9.38 22 8 7.25 20 8 9.88 23 8 5.00 14 476 8 9.75 22 11 11.18 22 7 10.43 25 8 10.75 25 14 11.57 26 16 10.94 27 477 8 8.13 21 8 9.00 22 9 9.67 27 8 8.50 24 15 7.93 29 20 7.55 29 478 9 9.33 21 12 12,42 29 11 10.36 29 12 13.00 41 9 11.11 27 9 10.00 28 480 14 8.86 26 14 8.71 24 13 8.62 23 16 9.69 29 16 8.19 26 31 7.71 27 481 16 8.06 27 13 10.62 32 16 10.00 30 16 10.69 31 23 9.91 36 36 11.53 40 482 7 7,43 19 9 7.56 19 9 9.89 22 8 10.88 26 11 10.45 28 12 9.75 30 483 8 9.38 21 7 11.29 21 8 11.38 22 8 12.38 25 8 10.75 24 8 11.50 26 484 10 10.10 22 12 11.17 26 11 9.73 24 13 12.38 31 15 11.60 29 12 10.83 26 485 9 9.11 22 12 10.58 22 11 12.91 28 13 13.54 35 22 12.64 37 11 13.09 35 490 8 11.25 32 11 15.09 35 11 14.36 29 12 16.33 39 15 16.33 40 16 15.25 34 491 10 10.70 30 12 11.08 26 11 14.00 30 12 13.17 34 15 12.67 36 12 13,75 33 492 12 10.42 28 12 12.75 31 12 10.33 32 12 13.08 32 15 12.27 37 12 12.75 30 493 9 12.11 28 12 12.58 27 11 12.09 31 12 13.17 32 12 13.83 32 11 13.82 37 494 8 10.63 26 8 13.38 26 8 11.63 28 8 12.38 31 8 11.75 25 9 11.67 25 495 8 7.75 22 8 9.75 20 7 12.00 24 8 10.38 24 8 11.13 27 8 10.38 23

37

Table 3. Common and scientific names of Scotia-Fundy finfish species.

Common name

AlbacoreAlewifeAlligatorfishAlligatorfish, ArcticAlligatorfishes (NS)American EelAmerican PlaiceAnchovy, StripedAnglemouth, LongtoothAnglemouth, VeiledAngler, AmericanAngler, DeepseaAnglerfishes (NS)Antimora, BlueArgentine, AtlanticArgentine, Large-EyedArgentine, StriatedArgentines (N.S.)Barracudina, DuckbillBarracudina, WhiteBarracudinas (NS)BarrelfishBasses, Sea (NS)Batfish, AtlanticBeardfishBeardfish, StoutBlackbackBlackfish, CornishBlacksmelt, GoitreBlenny, SnakeBlenny, Yarrell'sBlennys (NS)BluebackBluefishBonefishBonitoBonito, StripedBrillBulleyeButterfishButterflyfish, SpotfinButterflyfishes (NS)CapelinCardinalfish, Sherborn'sCardinalfishes (NS)Charr, ArcticChimeara, DeepwaterChimera, KnifenoseChimera, Longnose

Scientific name

Thunnus alalungaAlosa pseudoharengusAspidophoroides monopterygiusAsspidophoroides olrikiAgonidae f.Anguilla rostrataHippoglossoides platessoidesAnchoa hepsetusGonostoma elongatumCyclothone microdonLophius americanusCeratias holboelliLophiiformes o.Antimora rostrataArgentina silusNansenia groenlandicaArgentina striataArgentinidae f.Paralepis atlanticaNotolepis rissoi kroyeriParafe pis sp.Hyperoglyphe perciformesSerranidae f.Dibranchus atfanticusPolymixia loweiPolymixia nobilisPseudopleuronectes americanusCento/ophus medusophagusBathylagus euryopsLumpinus lumpretaeformesChirolophus ascaniiLumpenus sp.Alosa aestivalisPomatomus saltatrixAlbula vulpesSarda sardaKatsuwonus pelamisScophthalmus aquosusCookeolus boopsPeprilus triacanthusChaetodon ocellatusChaetodontidae f.Mallotus villosusHowella sherborniApogonidae f.Salvelinus alpinsHydrolagus affinisRhinochimera atlanticaHarriotta raleighana

Scientific name Common name

38

Table 3. (cont'd)

Chub, Bermuda Cod, Atlantic Cod, Atlantic Tom Cod, Greenland Cornetfish, Bluespotted Cunner Cusk Cutlassfishes (NS) Daggertooth Dogfish, Black Dogfish, Smooth Dogfish, Spiny Dogfishes (NS) Dolphin, Common (fish) Dory, American John Dory, Buckler Dory, Red Dragonet, Spotfin Dragonets, (NS) Dragonfish, Bluenose Dragonfish, Boa Dragonfish, Threelight Dragonfish, Torpedo Dragonfishes, Bighead (NS) Dragonfishes, Scaled (NS) Dragonfishes, Scaleless (NS) Eel, American Eel, Common Wolf Eel, Conger Eel, Duckbill Oceanic Eel, Gray's Cutthroat Eel, Green Moray Eel, Margined Snake Eel, Neck Eel, Ridged Eel, Slatjaw Cutthroat Eel, Snipe Eel, Snubnose Eel, Spiny Eelblenny, Slender Eelblenny, Stout Eelpout, Arctic Eelpout, Atlantic Eelpout, Checker Eelpout, Esmark's Eelpout, Laval's Eelpout, Newfoundland Eelpout, Pale Eelpout, Polar

Kyphosus sectatrix Gadus morhua Microgadus tomcod Gadus ogac Fistularia tabacaria Tautogolabrus adspersus Brosme brosme Trichiuridae f. Anotopterus pharao Centroscyllium fabricii Mustelus canis Squalus acanthias Squalidae f. Coryphaena hippurus Zenopsis conchifera Zenopsis conchifera Cuttus roseus Callionymus agassizi Callionymidae sp. Melanostomias spilorhynchus Stomias boa ferox Trigonolampa miriceps Grammatostomias dentatus Borostomias sp. Stomias sp. Melanostomiatidae f. Anguilla rostrata Lycenchelys paxillus Conger oceanicus Nessorhamphus ingolfianus Symaphobranchus kaupi Gymnothorax funebris Ophichthus cruentifer Derichthys serpentinus Neoconger mucronatus Symaphobranchus kaupi Nemichthys scolopaceus Simenchelys parasiticus Notocanthus chemnitzi Lumpinus fabricii Lumpenus medius Lycodes reticulatus Lycodes atlanticus Lycodes vahlii Lycodes esmarki Lycodes lavalaei Lycodes terraenova Lycodes pallidus Lycodes polaris


39

Table 3. (cont'd)

Eelpout, Vachon's Eelpout, Vahl's Eelpout, Wolf Eelpouts (NS) Eels, Conger (NS) Eels, Moray (NS) Eels, Spiny (NS) Eels (NS) Escolar Filefish, Fringed Filefish, Orange Filefish, Planehead Fish (Unidentified) Fishdoctor - Flounder, American Plaice Flounder, Blackback Flounder, Deepwater Flounder, Eyed Flounder, Fourspot Flounder, Gulfstream Flounder, Smallmouth Flounder, Smooth Flounder, Spotfin Flounder, Summer Flounder, Windowpane Flounder, Winter Flounder, Witch Flounder, Yellowtail Flounders, Lefteye (NS) Flounders, Righteye (NS) Flyingfishes (NS) Footballfish, Atlantic Frogfish, Ocellated Frogfishes (NS) Frostfish Gadoids (NS) Gaspereau Goatfish, Red Graysole Greeneye, Longnose Greeneye, Short-nosed Greeneyes (NS) Grenadier, Common Grenadier, Marlin-spike Grenadier, Rock Grenadier, Roughhead Grenadier, Roughnose Grenadier, Roundnose Grenadier, Saddled

Lycodes esmarki Lycodes vahlii Lycenchelys verrilli Lycodes sp. Conger sp. Muraenidae f. Notocanthidae f. Anguillidae f. Lepidocybium flavobrunneum Monacanthus ciliatus Aluterus schoepfi Monocanthus hispidus Pisces p. Gymnelis viridis Hippoglossoides platessoides Pseudopleuronectes americanus Monolene sessilicauda Bothus ocellatus Paralichthys oblongus Citharichthys arctifrons Etropus microstomus Liopsetta putnami Cyclopsetta fimbriata Paralichthys dentatus Scophthalmus aquosus Pseudopleuronectes americanus Glyptocephalus cynoglossus Limanda ferruginea Bothidae f. Pleuronectidae f. Exocoetidae f. Himantolophus groenlandicus Antennarius ocellatus Antennariidae f. Benthodesmus elongatus Gadidae f. Alosa pseudoharengus Mu//us auratus Glyptocephalus cynoglossus Parasudis truculenta Chlorophthalmus agassizi Chlorophthalamidae f. Nezumia bairdi Nezumia bairdi Coryphaenoides rupestris Macrourus berglax Trachyrhynchus murrayi Coryphaenoides rupestris Coelorhynchus coelorhynchus

40

Table 3. (cont'd)

Common name

Grenadier, StraptailGrenadiers (NS)Grouper, RedGrouper, SnowyGrubbyGunnel, BandedGunnel, RockGurnard, FlyingGymnast, AtlanticHagfishHake, BlueHake, LongfinHake, Off-shoreHake, RedHake, SilverHake, SpottedHake, SquirrelHake, WhiteHakes (merluccius) (NS)Hakes (urophycis) (NS)Halfbeak, CommonHalibut, AtlanticHalibut, GreenlandHatchetfish, SilverHatchetfishes (NS)Herring, AtlanticHerring, BluebackHerring, RoundHerrings (NS)Jack, CrevalleLamprey, SeaLancetfish, LongnoseLancetfish, ShortnosedLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfishLanternfish

Scientific name

Malacocephalus occidentallsMacrouridae f.Epinephelus morioEpinephelus niveatusMyoxocephalus aeneusPholis fasciataPholis gunnellusDactylopterus volitansXenodermichthys copeiMyxine glutinosaAntimora rostrataUrophycis chesteriMerluccius albidusUrophycis chussMerluccius bilinearisUrophycis regiusUrophycis chussUrophycis tenuisMerluccius sp.Urophycis sp.Hyporhamphus unifasclatusHippog/ossus hippoglossusReinharditus hippoglossoidesArgyropeiscus aculeatusSternoptychidae f.Clupea harengus harengusAlosa aestivalisEtrumeus teresClupeidae f.Caranx hipposPetromzon marinusAlepisaurus feroxAlepisaurus brevirostrisLepidophanes guentheriDiogenichthys atlanticusCentrobranchus nigroocellatusDiaphus rafinesquiiDiaphus termophilusMyctophum selenopsNotoscopelus caudispinosusLampadena luminosaNotolychnus valdiviaeHygophum hygomiiDiaphus mollisHygophum taaningiDiaphus perspicillatusProtomyctophum arcticumElectrona rissoNotoscopelus resplendens


41

Table 3. (cont'd)

Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish Lanternfish, Glacier Lanternfish, Horned Lanternfish, Jewel Lanternfish, Kroyer's Lanternfish, Largescale Lanternfish, Mettalic Lanternfish, Mirror Lanternfish, Spotted Lanternfishes (NS) Lightfishes (NS) Ling, Blue Ling, European Lookdown, Atlantic Loosejaw, Lightless Loosejaws (NS) Lumpfish Lumpsucker, Atl. Spiny Lumpsucker, Leatherfin Mackerel, Atlantic Mackerel, Chub Mackerel, Frigate Mackerel, King Mackerel, Spanish Mackerels, Snake (NS) Mako Manefish, Greenland Manta, Atlantic Man-of-war Fish Marlin, Blue Martin, White Marlin-spike Menhaden, Atlantics Monkfish Moonfish, Atlantic Moras (NS)

Lobianchia gemellarii Diaphus effulgens Bolinichthys photothorax Lampanyctus macdonaldi Lampanyctus ater Ceratoscopelus warmingii Myctophum asperum Notoscopelus bolini Lampanyctus photonotus Lampanyctus pusillus Lampanyctus festivus Diaphus taaningi Lampanyctus intricarius Benthosema suborbitale Benthosema glaciale

Ceratoscopelus maderensis Lampanyctus crocodilus Notoscopelus elongatus kroyerii Symbolophorus veranyi Myctophum affine Lampadena speculigera Myctophum punctatum Myctophidae f. Gonostomatidae f. Molva dypterygia Molva molva Selene vomer Malacosteus niger Malacosteidae f. Cyclopterus lumpus Eumicrotremus spinosus Eumicrotremus derjugini Scomber scombrus Scomber japonicus Auxis thazard Scomberomorus cavalla Scombromorus maculatus Gempylidae f. lsurus oxyrinchus Caristicus groenlandicus Manta birostris Nomeus gronovii Makaira nigricans Makaira albida Nezumia bairdi Brevoortia tyrannus Lophius american Selene setapinnis Moridae f.


42

Table 3. (cont'd)

Moray, Green Morays (NS) Mullets (NS) Myctophid (NS) Neckeel Ocean Pout Oilfish Opah Pearlsides, Muller's Pilotfish Pipefish (NS) Plaice, American Poachers (NS) Pollock Pomfret, Atlantic Pomfret, Bigscale Pompano, Common Porbeagle Porcupinefishes (NS) Porgies (NS) Pout, Atlantic Soft Pout, Ocean Pricklebacks (NS) Puffer, Northern Puffer, Oceanic Redfish, Acadian Redfish, Deepwater Redfish, Golden Redfish, Labrador Redfishes (NS) Remora Remora, Spearfish Rockfishes (NS) Rockling, Fourbeard Rockling, Silver Rockling, Threebeard Rocklings (NS) Rosefish, Blackbelly Rudderfish, Banded Ruff, Black Ruff, Brown Runner, Blue Sagre, Rough Sailfish, Atlantic Salmon, Atlantic Sandlance, American Sandlance, Northern Sandlances (NS) Sargassumfish

Gymnothorax funebris Muraenidae f. Mugilidae f. Myctophidae f. Derichthys serpentinus Macozoarces americans Ruvettus pretiosus Lampridae guttatus Maurolicus muellefi Naucrates ductor Syngnathus sp. Hippoglossoides platessoides Agonidae f. Pollachius virens Brama brama Taractichthys longipinnis Trachinotus carolinus Lamna nasus Diodontidae f. Sparidae f. Melanostigma atlanticum Macozoarces americans Stichaeidae f. Sphoeroides maculatus Lagocephalus lagocephalus Sebastes fasciatus Sebastes mentella Sebastes marinus Sebastes fasciatus Sebastes sp. Remora remora Remora brachyptera Scorpaena sp. Enchelyopus cimbrius Gaidropsaurus argentatus Gaidropsarus ensis Gaidropsarus sp. Helicolenus dactylo pterus Seriola zonata Centrolophus niger Centolophus medusophagus Caranx crysos Etmopterus princeps Istiophorus platypterus Salmo salar Ammodytes americanus Ammodytes dubius Ammodytidae f. Histrio histrio

43

Table 3. (cont'd)

Common name

Saury, AtlanticSawpalate, StoutSawtailfish, RibbonScabbardfish, BlackScad, BigeyeScad, MackerelScorpionfishes (NS)Sculpin, ArcticSculpin, Arctic HookearSculpin, Arctic StaghornSculpin, Atlantic HookearSculpin, BigeyeSculpin, CommonSculpin, FourhornSculpin, GrubbySculpin, Hookear (NS)Sculpin, LittleSculpin, LonghornSculpin, MailedSculpin, MoustacheSculpin, Nybelin'sSculpin, PallidSculpin, PolarSculpin, RibbedSculpin, ShorthornSculpin, Snowflake HookearSculpin, SpatulateSculpin, TwohornSculpins (NS)ScupSea LampreySea Poacher, AtlanticSea Poachers (NS)Sea RavenSea TadpoleSearobin, CommonSearobin, NorthernSearobin, StripedSearobins (NS)Seasnail, BlacksnoutSeasnail, DuskySeasnail, GelantinousSeasnail, GreenlandSeasnail, InquilineSeasnail, StripedSeasnails (NS)Seasnails (NS)Shad, AmericanShanny, Arctic

Scientific name

Scomberesox saurusSerrivomer beaniIniacanthus fasciolaApahanopus carboSelar crumenophthalmusDecapterus macaellusScorpaenidae f.Myoxocephalus scorpioidesArtediellus uncinatusGymnocanthus tricuspisArtediellus atlanticusTriglops nybeliniMyoxocephalus octodecemspinosusMyoxocephalus quadricornisMyoxocephalus aeneusArtediellus sp.Myoxocephalus aeneusMyoxocephalus octodecemspinosusTriglpos murrayiTriglpos murrayiTriglops nybeliniCottunculus thompsoniCottunculus micropesTriglops pingeliMyoxocephalus scorpiusArtediellus uncinatusIcelus spatulalcelus bicornisCottidae f.Stenotomus chrysopsPetromzon marinusAgonus decagonusAgonidae f.Hemitripterus americanusCareproctus reinhardiPriondius carolinusPriondius carolinusPrionotus evolansTriglidae f.Paraliparis copeiLiparis gibbusLiparis fabriciiLiparis tunicatusLiparis inquilinusLiparis liparisLiparis sp.Careproctus sp.Alosa sapidissimaStichaeus punctatus


■

44

Table 3. (cont'd)

Shanny, Daubed Shanny, Radiated Shark, Atl, Sharpnose Shark, Basking Shark, Blue Shark, Deepsea Cat Shark, Dusky Shark, Greenland Shark, Porbeagle Shark, Po rtuguese Shark, Sand Tiger Shark, Shortfin Mako Shark, Smooth Hammerhead Shark, Thresher Shark, White Shark, Whitetip Sharks (NS) Sharksucker Sheepshead Silverside, Atlantic Skate, Arctic Skate, Barndoor Skate, Eyed Skate, Jensen's Skate, Little Skate, Round Skate, Shorttail Skate, Smooth Skate, Soft Skate, Spinytail Skate, Thorny Skate, White Skate, Winter Skates and Rays (NS) Skates (NS) Skipjack Smelt, Rainbow Smelts/Capelins (NS) Smoothhead, Baird's Smoothhead, Bluntsnout Snailfish, Atlantic Snailfish, Dusky Snailfish, Gelatinous Snailfish, Greenland Snailfish, lnquiline Snake Mackerels (NS) Snakeblenny Sole, Gray Spiderfishes (NS)

Lumpenus maculatus Ulvaria subbifurcata Rhizoprionodon terraenovae Cetorhinus maximus Prionace glauca Apristurus profundorum Carcharhinus obscurus Somniosus microcephalus Lamna nasus Centroscymnus coelolepis Odontaspis taurus lsurus oxyrinchus Sphyma zygaena Alopias vulpinus Carcharodon carcharias Carcharhinus longimanus Squaliformes o. Echeneis naucrates Archosargus probatocephalus Menidia menidia Raja hyperborea Raja laevis Raja ocellata Raja jenseni Raja erinacea Raja fyllae Raja jenseni Raja senta Raja mollis Raja spinicauda Raja radiata Raja lintea Raja ocellata Batoidei o. Rajidae f. Katsuwonus pelamis Osmerus mordax Osmeridae f. Alepocephalus bairdii Xenodermichthys copei Liparis atlanticus Liparis gibbus Liparis fabricii Liparis tunicatus Liparis inquilinus Gempylidae f. Lumpinus lumpretaeformes Glyptocephalus cynoglossus Chlorophthalamidae f.

Common name Scientific name

45

Table 3. (cont'd)

Spiny Eels (NS) Stingray, Pelagic Stingray, Roughtail Sturgeon, Atlantic Sturgeon, Shortnosed Sturgeons (NS) Sunfish, Ocean Swallower, Black Swallowers (NS) Swordfish Tadpole, Sea Tapirfish, Backfin Tapirfish, Largescale Tapirfish, Shortspine Tapirfishes (NS) Tarpon Tautog Tilefish Tomcod, Alantic Torpedo, Atlantic Triggerfish, Gray Triggerfish, Ocean Tuna, Albacore Tuna, Atl. Bonito Tuna, Bigeye Tuna, Bluefin Tuna, False Albacore Tuna, Skipjack Tuna, Yellowfin Tunas (NS) Tunny, Little Turbot Viperfish, Sloan's Wahoo Warbonnet, Atlantic Whiting, Blue Windowpane Witch Wolf Eel, Common Wolffish, Atlantic Wolffish, Northern Wolffish, Spotted Wolffishes (NS) Wrasses (NS) Wrymouth Yellowtail Angler, Lesser Deepsea Cod, Arctic Haddock Sea Devil, Triplewart Triggerfish, Queen

Notocanthidae f. Dasyatis violacea Dasyatis centroura Acipenser oxyrhynchus Acipenser brevirostrum Acipenseridae f. Mola mola Chiasmodon niger Chiasmodontidae f. Xiphias gladius Careproctus reinhardi Lipogenys Notocanthus chemnitzi Polycanthonotus rissoanus Notocanthidae f. Megalops atlanticus Tautoga onitis Lopholatilus chamaeleonticeps Microgadus tomcod Torpedo nobilana Balistes capriscus Canthidermis sufflamen Thunnus alalunga Sarda sarda Thunnus obesus Thunnus thynnus Euthynnus alletteratus Katsuwonus pelamis Thunnus albacares Thunnus sp. Euthynnus alletteratus Reinharditus hippoglossoides Chauliodus sloani Acanthocybium solanderi Chirolophus ascanii Micromesistius poutassou Scophthalmus aquosus Glyptocephalus cynoglossus Lycenchelys paxillus Anarhichas lupus Anarhichas denticulatus Anarhichas minor Anarhichadidae f. Labridae f. Cryptacanthodes maculatus Limanda ferruginea Cryptopsaras couesi Boredgadus saida Melanogrammus aeglefinus Cryptopsaras couesi Batistes vetula

46

Table 4. Summary of seasonal survey results by stratum 1979-85. The number of tows (A), the mean number ofspecies per tow (B), and the total number of species observed (C).

Spring Summer Fall

Str A B C A B C A B C

440 3 12.0 18 22 10.0 37 16 11.0 32441 3 6.7 18 23 9.7 37 15 10.7 34442 3 5.3 11 21 6.3 32 17 7.4 28443 14 6.6 23 28 6.0 29 19 6.4 26444 16 8.6 27 32 7.8 38 26 9.0 31445 17 11.2 32 30 8.9 45 22 10.4 39446 14 12.7 29 22 11.4 40 17 11.9 41447 22 7.1 18 29 8.0 20 24 7.3 23448 22 6.7 21 30 7.8 24 24 8.5 29449 12 8.9 22 13 6.4 17 10 6.8 18450 18 10.8 27 21 8.7 28 25 10.7 30451 12 11.9 31 15 9.9 31 17 10.4 40452 12 12.1 31 16 12.3 34 24 14.6 .41453 18 12.7 35 21 10.6 37 18 12.8 41454 18 8.9 29 20 8.3 29 24 11.1 40455 40 7.6 22 50 10.5 29 41 9.9 29456 32 7.3 28 42 9.7 32 36 10.2 32457 10 10.4 29 15 7.9 29 22 11.6 36458 15 5.1 24 21 8.1 23 18 8.7 24459 17 11.2 36 29 10.3 47 25 11.0 37460 15 12.7 30 14 11.7 31 14 10.6 27461 14 10.0 21 14 10.7 23 14 10.9 23462 24 12.1 32 30 11.2 35 27 11.2 33463 13 8.7 24 15 6.9 25 12 8.8 19464 30 8.6 30 34 9.4 33 29 9.4 29465 30 11.1 35 38 9.2 38 34 9.4 37466 18 13.1 38 20 10.4 35 17 10.8 44470 15 13.4 30 14 12.9 26 12 13.1 29471 16 12.0 29 14 10.7 25 13 11.0 28472 15 9.3 32 15 10.0 32 14 9.4 34473 14 5.7 19 14 5.4 16 12 7.0 34474 10 6.9 22 12 7.1 24 12 5.8 37475 14 11.9 34 14 8.1 24 12 11.0 40476 14 12.9 30 13 10.5 29 14 12.6 34477 16 11.6 29 15 8.7 30 14 11.6 32478 17 12.7 34 21 11.9 46 17 13.1 47480 27 9.0 26 26 9.2 30 24 10.0 32481 28 10.8 37 27 10.2 36 22 11.3 37482 15 11.1 30 15 10.2 27 12 10.7 27483 8 11.1 25 14 12.2 27 13 10.7 23484 22 13.0 36 22 11.3 28 21 12.2 27485 19 13.9 36 21 13.6 36 19 15.2 36490 16 13.1 37 20 15.7 39 14 16.9 38491 15 13.3 34 20 13.6 33 18 14.8 40492 16 14.9 34 21 11.7 33 18 14.7 39493 11 13.0 30 20 12.8 38 14 17.1 43494 8 10.6 23 14 12.1 34 10 12.3 26495 9 11.9 29 14 11.1 30 10 14.5 29

47

Table 5. Residency status of species compliment by stratum and season.

Strat Total # of % of species % of species % of species % of species species in spring in summer in fall all seasons

440 42 43 88 76 36 441 47 38 79 72 32 442 42 26 76 67 19 443 37 62 78 70 49 444 46 59 82 67 46 445 54 59 83 72 46

446 55 53 73 75 38 447 26 69 77 88 50 448 33 64 73 88 52

449 28 79 60 64 32 450 40 68 70 75 48 451 51 61 61 78 45 452 54 58 63 76 39 453 55 64 67 75 47 454 49 59 59 81 39 455 34 65 85 85 58 456 39 72 82 82 59 457 42 69 69 86 50

458 33 73 70 73 49 459 51 71 92 73 65 460 36 83 86 75 67 461 32 66 72 72 47 462 42 76 83 79 67 463 31 77 81 61 48 464 40 75 83 73 58 465 53 66 72 70 45 466 60 63 58 73 37 470 37 81 70 78 51 471 34 85 74 82 59 472 45 71 71 76 53 473 36 53 44 94 36 474 40 55 60 93 45 475 44 77 55 91 52 476 38 79 76 90 66 477 39 74 77 82 64 478 65 52 71 72 40 480 40 65 75 80 50 481 46 80 78 80 65 482 39 77 69 69 46 483 39 64 69 59 41 484 42 86 67 64 47 485 47 77 77 77 58

490 48 77 81 79 54 491 45 76 73 89 60 492 43 79 77 91 65 493 49 61 78 88 51 494 44 52 77 59 30 495 43 67 70 67 40

46 •

48

50 Path 43 51 100 Path .44

100 Path 45

44.

—

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550

.1

51 •l00

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1

Figure 1 Scotia - Fundy Summer Survey Stratification Scherne

a ,..•• 0

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SCATARIE

Figure 2. Offshore Banks and Basins of the Scotia-Fundy Region.

49

Cumulative Number of Species Reported by Stratum

60 -,

40

30

20 -I

10

--+-4 4 0

--441

-6-442

••1&•443

-•t•444

ti-445

65 70 75 60 65 90 95

Year

Figure 3.

60 7

10 .-I

0

-m-452

--2-453

-4-454

--r•-4 5 5

-•+•456

-+e-457.^^n

65 70 75 t0 85 90 95

Year

Figure 5.

60 -,

50

40

30

I20

10 -i

0

-+-446

--a -447

-+-448

--o--449

•-+• 4 5 0

-+-451

65 70 75 60 as 90 95

Year

Figure 4

65

-+-+15 8

-+-459

-•-460

-- -_4 61

L

+-462

a-46311-;;!

70 75 s0 65 90 95

Year

Figure 6.

50

Cumulative Number of Species Reported by Stratum

60 -i

50

40

30

20

--- 464

---w-465

-4-466

••w•470

.•+-471

--472 a.3. i

r-" D.P^ffi .0 6.4

10 --I

0

60

30

20

10

66 70 75 80 85 90 95

Year

Figure 7.

--•,480-dm -481

-•-482

--»-•483

•-+--484

-+-485

60 -,

50

40

30

20

7 0 -I

0

--t-473

-a-474

-*-475

--w-476

--^-477

-&-47e

t

r'r

A

IM^

^

J0194

e,1► «k$(1 «V Mce4l a - mm". ,^^..t.

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65 70 75 80 85 90 95

Year

Figure 8.

60 -

5o

40

30

20

1 0 --^

-'*--490

--491

-•-492

--«•493

--é-494

-+-495

0 o

65 70 75 80 85 90 95

Year

Figure 9.

I

65 70 75 80 85 90 95

Year

Figure 10.

51

Figure 11. Sampling Effort and Effectiveness for Summer Surveys

3

2

44V

1

42V

41 45

40' 52j4g0 82^ V64 66

62 n 7 •0 46 •56

•7551^

♦

^ ^ 1 :795 9^54 •5850

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1À • 7494 80 •

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.0

• Mid-depthsV EdgeA Fundyn Basins• Banks

-1

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Stations per Square Nautical Mile

68 ° 66 64 62 60 58 56

Species per tow

1 1 1 1 1 1 68° 66 64 62 60 58 56

52

Figure 12. Diversity in summer 1970-73


53

68° 66 64 62 60 58 56


68° 66 64 62 60 58 56


54


I I I I I I

68° 66 64 62 60 58 56

I I I I I I 68° 66 64 62 60 58 56


Mea

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mbe

r of s

pec

ies

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ow

65 70 75 80 85 90 95

Year

55

Figure 18. Trends in the mean number of species caught by

the Cameron (A), the Needier (B) and across both vessels (C).

7 56

01990-93 Ili 1986-89

1982-85

1978-81

Q1111974-77

BM 1970-73

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I lYi l h I gi l l WO m111 El M il l ire9 1 41 1

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Figure 19. Species Composition of Stratum 440 in Summer since 1970

O 1990-93

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24 H

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Mean Number of Species per Tow

22 6

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Diversity of finfish species in the Scotia–Fundy region

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