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Pelagic Longline Take Reduction Team Update: Abundance and MortalitySeptember 16 2010
Dr. Lance P. Garrison
Dr. Patricia Rosel
Southeast Fisheries Science Center
Abundance Estimate
(CV)Nmin
Potential Biological Removal
Combined Short-finned and Long-
finned(2009 SAR)
31,139 (0.27) 24,866 249
Long-finned pilot whale
(Draft 2010 SAR)12,619 (0.37) 9,333 93
Short-finned pilot whale
(Draft 2010 SAR)24,674 (0.45) 17,190 172
Revised Abundance Estimates: Draft 2010 SAR
Average Mortality and Serious Injury (combined) 2004-2008: 175 (CV = 0.14)
Splitting Abundance Estimates: Approach
Analytical Approach: Logistic regression to predictthe probability of a sample being from shortfin(or longfin) pilot whale based on location of sample, waterdepth, surface water temperature, surface chlorophyll
Habitat Data: Remotely sensed habitat SST (1 km) and CHL (4km) 8-day composites used to extract values based on sample location/collection date. Bottom depth from 1-minuteresolution bathymetry grid.
Prediction: Predict the probability that an observed groupof pilot whales is of a particular species based on environmental conditions at sighting location. Use thisprobability to partition abundance estimates from 2004surveys.
Year Month Long-finned Short-finned Total
1998 July 55 0 551998 August 2 0 22001 August 1 0 12004 June 0 6 62004 July 45 27 722005 July 6 77 832006 July 0 87 872006 August 0 3 32007 July 1 0 12007 August 11 17 28
TOTAL 121 217 338
Pilot Whale Abundance Estimates: Biopsy Samples from June-August
Includes both Field Collection and Bycatch
Pilot Whale Abundance Estimates: Biopsy Samples from June-August
Pilot Whale Abundance Estimates: Logistic Regression Results
Best model included Depth, SST and their Interaction effect
Pilot Whale Abundance Estimates: 2004 Summer Pilot Whale Sightings
All sightings in the NEC aerial surveys are expected to be long-finned pilot whales.Abundance estimate:11,038 (CV = 0.4)
All sightings in the SEC ship survey are expected to be short-finned pilot whalesAbundance estimate:21,056 (CV = 0.5)
Sightings in the NEC ship survey are in the mixed zone.
Pilot Whale Abundance Estimates: Probability of Being Short-finned
SpeciesBootstrap
Mean Abundance
Bootstrap 95% Confidence
Limit
Short-finned
3,618 1,112 – 8,294
Long-finned
1,581 130 – 5,307
Pilot Whale Abundance Estimates
Survey Latitude Range SpeciesAbundance estimate
(CV)
Atlantic Cetacean Survey (SEFSC )
28° N to 38° N Short-finned 21,056 (0.52)
Northeast Cetacean Survey - Vessel (NEFSC)
38° N to 41° N MixedSF - 3,618 (0.50)
LF - 1,581 (0.86)
Northeast Cetacean Survey - Aerial (NEFSC )
41° N to ~45° N Long-finned11,038(0.40)
Total Abundance Estimates (CV)Short-finned 24,674 (0.45)
Long-finned 12,619 (0.37)
Pilot Whale Abundance Estimates
Pilot Whale Bycatch and Biopsy Data
Limited Data to Parse Out Mortality Estimates
Longline Observer Biopsy Samples
false killer whale
Risso’s dolphin
SF pilot whale, common dolphin
minke whale
bottlenose dolphin
pantropical spotted dolphin
pantropical spotted dolphinsperm whalepygmy sperm whale
Longline Observer Biopsy Samples
We have received 10 biopsy samples between November 2008 and April 2010
• Wide variety of species• 1 short-finned pilot whale off of New Jersey
Field Identification Genetic IdentificationUnknown marine mammal Sperm whalePilot whale False killer whaleBottlenose dolphin Not run yetRisso’s dolphin Not run yetPantropical spotted dolphin Pantropical spotted dolphinPilot whale sp. Short-finned pilot whaleCommon dolphin Common dolphinUnidentified large whale Minke whalePantropical spotted dolphin Pantropical spotted dolphinDwarf sperm whale Pygmy sperm whale
Observed Interactions - 2009
Quarter CAR FEC GOM MAB NEC NED SAB SAR TUN Total
1 0.00 12.09 9.31 4.10 - - 22.40 22.77 0.00 11.90
2 0.00 6.00 58.25 7.36 0.00 0.00 8.18 42.94 9.42 30.12
3 - 8.38 7.44 9.22 14.36 16.57 4.52 - 0.00 9.24
4 - 10.35 11.53 10.52 28.61 0.00 15.59 32.81 0.00 12.06
Total 0.00 9.54 22.40 9.08 14.11 12.43 11.96 27.42 3.31 15.80
Percent Observer Coverage - 2009
Observed Interactions - 2009
Species DeadSerious Injury Released Alive Total
Pilot Whale 0 2 2 4
Risso's Dolphin 0 2 3 5
Bottlenose Dolphin 0 2 1 3
Common Dolphin 1 0 0 1
Pantrop. Spotted Dolphin 0 4 1 5
Unid. Dolphin 0 0 1 1
Unid. Marine Mammal 0 1 0 1
Total 1 11 8 20
Pilot Whale Bycatch Rates- 2009
Quarter Area2005-2008
CPUE2005-200895% CI
2009CPUE
200995% CI
1 MAB 0.2996 0.1349 – 0.6649 0 -
2 MAB 0.1114 0.0339 – 0.3669 0 -
3 MAB 0.1783 0.1065 – 0.2984 0.0208 0.0041 – 0.1065
3 NEC 0.0091 0.0019 – 0.0443 0.0272 0.0053 – 0.1389
4 MAB 0.1148 0.0596 – 0.2210 0.0406 0.0116 – 0.1382
Pilot whale bycatch rates were lower than normal in each quarter. No interactions in quarters 1 & 2. No serious injuries observed in quarter 3.
Risso’s Bycatch Rates- 2009
Quarter Area2005-2008
CPUE2005-200895% CI
2009CPUE
200995% CI
3 MAB 0.0046 0.0009 – 0.0226 0.0242 0.0047 – 0.1239
3 NEC 0.0258 0.0075 – 0.0891 0.0689 0.0245 – 0.1934
3 NED 0 - 0.0274 0.0054 – 0.1401
4 MAB 0.0271 0.0110 – 0.0670 0 -
4 NEC 0.0476 0.0097 – 0.2327 0 -
Risso’s Dolphin bycatch rates were higher in the 3rd quarter, but lower in the 4th Quarter.
Estimated Annual Bycatch - 2009Species Alive
Alive 95% CI
Serious Injury/Mortality
SI 95% CI
Total
Common Dolphin 0 - 8.5 1.7 – 43.4 8.5
Bottlenose Dolphin
11.3 2.2 – 57.6 11.6 3.0 – 44.8 22.9
Pantropical Spotted Dolphin
12.5 2.4 – 63.9 14.0 4.4 – 45.5 26.5
Risso’s Dolphin 27.1 9.1 – 80.9 11.4 3.3 – 39.9 38.5
Pilot Whale 19.2 5.4 – 67.9 16.5 4.8 – 56.8 35.7
Unid. Dolphin 1.6 0.3 – 8.2 0 - 1.6
Unid. Marine Mammal
0 - 8.0 1.6 – 41.2 8.0
Pilot Whale Bycatch and Effort Trends
Risso’s Dolphin Bycatch and Effort Trends
Observed Bycatch Quarters 1 and 2 of 2010
Species Region# Released Un-
injured# Dead # Serious Injury
Pantropical Spotted Dolphin GOM 1 0 0
Unidentified Marine Mammal GOM 0 1 0
Pilot Whale FEC 0 0 1
Minke Whale SAB 1 0 0
Species Region# Released Un-
injured# Dead # Serious Injury
Un-identified Dolphin GOM 1 0 0
Bottlenose DolphinGOM(Exp.)
0 0 1
Unidentified Marine Mammal GOM 0 0 1
Pygmy Sperm Whale GOM 0 1 0
Pilot Whale MAB 0 0 3
Bottlenose Dolphin SAB 1 0 0
Quarter 1
Quarter 2
Observed Bycatch Quarters 1 and 2 of 2010
Quarter Species Area2005-2009
CPUE
2005-200995% CI
2010CPUE
201095% CI
1 Pilot Whale FEC 0 - 0.07020.0137 – 0.3588
1 Pilot Whale MAB 0.27810.1251 –
061880 -
2 Pilot Whale MAB 0.00680.0201 –
0.2220.8403
0.1607 – 4.309
Bycatch Rates Quarters 1 and 2 of 2010
Very high bycatch rate in quarter 2. 3 Pilot whale SI in one set.
Mainline Length in MABBefore and After PLTRP Rule