Post on 23-Jan-2021
transcript
Michael P. SekiNOAA Fisheries
Pacific Islands Fisheries Science Center
Micronekton in the North Pacific … what do we know?
““micronekton” defined …micronekton” defined …
Small but actively swimming organisms ranging from ca. 2 to 10 Small but actively swimming organisms ranging from ca. 2 to 10 cm; mainly mesopelagic (200-1000 m depths)cm; mainly mesopelagic (200-1000 m depths)
Taxa too vagile to be caught with conventional plankton nets Taxa too vagile to be caught with conventional plankton nets yet too small to be retained by most large trawls.yet too small to be retained by most large trawls.• Fishes – mainly mesopelagics and juveniles of epipelagic Fishes – mainly mesopelagics and juveniles of epipelagic
nektonnekton• Crustaceans – includes adult euphausiids, pelagic Crustaceans – includes adult euphausiids, pelagic
decapods, mysids, hyperiid amphipodsdecapods, mysids, hyperiid amphipods• Cephalopods – small adults and subadults of large Cephalopods – small adults and subadults of large
oceanics oceanics Many undertake extensive diel vertical migrationsMany undertake extensive diel vertical migrations
Why do we care?Why do we care?
● Represents a substantial biomass in the Represents a substantial biomass in the world’s oceansworld’s oceans
● A critical but poorly understood A critical but poorly understood intermediate (missing?) trophic link intermediate (missing?) trophic link between the mesozooplankton & higher between the mesozooplankton & higher trophic levels (i.e., fish, marine mammals, trophic levels (i.e., fish, marine mammals, etc.)etc.)
● Significant contributors to the “biological Significant contributors to the “biological pump” (i.e., rapid transport of Cpump” (i.e., rapid transport of Csurfacesurface, as , as well as pollutants, to deep sea).well as pollutants, to deep sea).
Relatively scant attention paid to Relatively scant attention paid to micronekton as a wholemicronekton as a whole
In 1997, PICES establishes a WG to In 1997, PICES establishes a WG to assimilate knowledge of micronekton assimilate knowledge of micronekton & their sampling in the North Pacific& their sampling in the North Pacific
Broadly, much of what is known Broadly, much of what is known results from research of the 1960s & results from research of the 1960s & 70s70s
… … most focused on the marginal seas most focused on the marginal seas around the basin rim (i.e., we know around the basin rim (i.e., we know least about the open ocean)least about the open ocean)
… … and little effort expended in and little effort expended in comparing relative sampling comparing relative sampling efficiencies and selectivity of the gearsefficiencies and selectivity of the gears
Some history and milestones of micronekton Some history and milestones of micronekton research around Hawaii and the Central North research around Hawaii and the Central North Pacific:Pacific:
● King & Iversen (1962): oceanic Central Pacific & Hawaii – 6’ & 10’ King & Iversen (1962): oceanic Central Pacific & Hawaii – 6’ & 10’ IKMT; zIKMT; zmaxmax ~ 350 m ~ 350 m
● Clarke, Young, and others (1972-78): off Hawaii; 6’ & 10’ IKMT, Cobb Clarke, Young, and others (1972-78): off Hawaii; 6’ & 10’ IKMT, Cobb trawl; ztrawl; zmaxmax to 1200 m to 1200 m
● Wilson, Boehlert and others (1985-88): Hancock Smts – Wilson, Boehlert and others (1985-88): Hancock Smts – “engybenthic” micronektonic fauna; qualitative acoustics“engybenthic” micronektonic fauna; qualitative acoustics
● Reid et al. (1991): off Hawaii; Mesopelagic Boundary Community Reid et al. (1991): off Hawaii; Mesopelagic Boundary Community (MBC); IOS-RT 40 m(MBC); IOS-RT 40 m22, HU-200 m, HU-200 m22 trawl; z trawl; zmaxmax ~500-600 m ~500-600 m
● Benoit-Bird and Au: off Hawaii (2001-2003): MBC, quantitative Benoit-Bird and Au: off Hawaii (2001-2003): MBC, quantitative acoustics, horizontal migration, micro-patches)acoustics, horizontal migration, micro-patches)
● PICES (2004): off Hawaii; 6’ IKMT, Cobb trawl, HU-RT gear PICES (2004): off Hawaii; 6’ IKMT, Cobb trawl, HU-RT gear comparison; quantitative acousticscomparison; quantitative acoustics
SE Hancock Acoustic transects, July 1984SE Hancock Acoustic transects, July 1984(38 kHz Simrad echo sounder)(38 kHz Simrad echo sounder)
1941-h 0330-h 0430-h 0630-h
““Minimum no. species caught”Minimum no. species caught”
Summer ‘84Summer ‘84 Winter ‘85Winter ‘85 ‘ ‘on’ ‘off’ ‘on’ ‘off’on’ ‘off’ ‘on’ ‘off’
No. tows 12 6 12 10No. tows 12 6 12 10
Crustaceans Crustaceans 23 26 23 2923 26 23 29Fishes Fishes & cephalopods & cephalopods 21 2421 24 47 6147 61
Fishes & SquidFishes & Squid
Maurolicus muelleri
Species "on" "off" "on" "off"
Maurolicus muelleri 4.19 (2) 0.06 0.17 --Lampanyctus alatus 0.03 0.02 0.09 0.90 (5)Ceratoscopelus townsendi 0.20 0.20 0.20 0.60Vinciguerria nimbaria 0.80 0.03 0.39 0.73Vinciguerria attenuata 0.17 0.93 0.02 0.16
Iridoteuthis iris 0.35 0.03 0.25 --Onychoteuthis n. sp. D -- -- 0.24 0.46Megalocranchia cf. fisheri -- -- 0.10 0.20
Summer (Jul-Aug '84) Winter (Jan-Feb '85)
Mean densities (individuals/1000 m3 water filtered) of selected micronekton species in the vicinity of SE Hancock
(number in parentheses indicate rank among top five species)
Vinciguerria nimbariaVinciguerria nimbaria
Iridoteuthis irisIridoteuthis iris
CrustaceansCrustaceans
Gnathophausia longispina
Gennadas propinquus
Oplophorus spinosus
Euphausia gibboidesSpecies "on" "off" "on" "off"
Gnathophausia longispina 11.60 (1) 2.59 (4) 7.26 (1) --
Euphausia gibboides 1.23 (4) 5.50 (1) 6.98 (2) 3.27 (2)Euphausia hemigibba 0.82 (5) 1.93 2.65 (3) 4.28 (1)Euphausia mutica 1.38 (3) 2.24 (5) 0.24 0.28Thysanopoda monacantha 0.07 2.81 (3) 0.37 1.09 (4)Thysanopoda orientalis 0.15 3.75 (2) -- 0.06Thysanopoda tricuspidata -- 0.02 0.50 0.29Stylocheiron abbreviatum 0.19 0.91 0.76 1.57 (3)Thysanoessa gregaria -- -- 0.10 0.01
Gennadas incertus -- 0.2 -- 0.6 (5)
Oplophorus spinosus 0.01 0.29 0.03 0.29
Mean densities (individuals/1000 m3 water filtered) of selected micronekton species in the vicinity of SE Hancock
(number in parentheses indicate rank among top five species)
Summer (Jul-Aug '84) Winter (Jan-Feb '85)
Cobb trawls at large-scale frontal systems, SAFZ August 1991Cobb trawls at large-scale frontal systems, SAFZ August 1991
Subarctic Domain
Subarctic Frontal Zone
"Subarctic Boundary"
Transition Zone
Pyr
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. D*
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"Cold-water" boreal-subarctic
Salinity (PSU)
32 33 34 35 36
Tem
pera
ture
(°C)
0
5
10
15
20
25
42°N
46°N
45°N
44°N
43°N
41°N
39°N
38°N
F t = 23.0
F t = 24.0
Ft = 25.0
Ft = 26.0 Ft = 27.0 Ft = 28.0
F t = 22.0
179°30'W
Cobb trawls at large-scale frontal systems, STFZ February 1992Cobb trawls at large-scale frontal systems, STFZ February 1992
Salinity (PSS 78)33 34 35 36
Tem
pera
ture
(°C)
5
10
15
20
25
31°08.0'N152°55.6'W
29°18.7'N153°50.5'W
27°27.5'N 154°41.3'W
25°41.1'N155°42.3'W
23°40.1'N156°34.4'W
21°45.5'N157°14.6'W
Ft= 23.0
F t= 24.0
Ft= 25.0
Ft= 26.0 Ft= 27.0 Ft= 28.0
B
Transition Zone
Subtropical Frontal Zone
Subtropical Domain
Abr
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Abr
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0
2
dorsal mantle length (mm)
0 20 40 60 80 100 120 1400
3
6
9
12
15South Transition - Subtropical Frontal Zone
freq
uenc
y
0
5
10
15
20
25
30
Onychoteuthis borealijaponicaOnychoteuthis sp. D
Northern Transition Zone
0
2
4Subarctic Frontal Zone
Subarctic Domainn = 5
n = 8
n = 99n = 23
n = 51
Onychoteuthis sp. D & O. borealijaponica
• South spawning – north feeding migrations
• Spatially complementary distributions
• Past reports of extensive distribution likely a composite of 2 species
Cruise objectives:Cruise objectives: to conduct the sampling for a to conduct the sampling for a
gear comparison and to gain gear comparison and to gain a subtropical perspective of a subtropical perspective of the micronekton communitythe micronekton community
use the benign weather and use the benign weather and sea conditions to evaluate sea conditions to evaluate and refine the protocols, and refine the protocols, logistics, and design of the logistics, and design of the experimentexperiment
PICES Micronekton Inter-calibration Experiment (MIE)NOAA ship Oscar Elton Sette cruise 04-13
October 6-13, 2004
Micronekton Intercalibration Experiment – 1 Cruise participants
Michael P. Seki Evgeny Pakhomov Daniel Curran Larissa PakhomovaDonald R. Hawn University of British ColumbiaReka Domokos Dept. Earth & Ocean Sciences National Marine Fisheries Service, NOAA Pacific Islands Fisheries Science Center
Richard Brodeur Hiroki Yasuma National Marine Fisheries Service, NOAA Masayuki AbeNW Fisheries Science Center, Newport OR Hokkaido University
Graduate School of Fisheries Sciences & Faculty of FisheriesDoug Yelland Institute of Ocean Sciences Andrei Suntsov Department of Fisheries & Oceans, Canada Harbor Branch Oceanographic Institution
140 m140 m22 “Stauffer modified” “Stauffer modified” pelagic Cobb trawlpelagic Cobb trawl
Sampling gears
1.8 m IKMT
2 m Hokkaido University Rectangular Frame Trawl
MIE-1, operations tracksMIE-1, operations tracks
EK-60 38 kHz echogram, 9 October 2004:EK-60 38 kHz echogram, 9 October 2004:
Day tows ≈ 550 m
Night tows ≈ 120 m
One series night tows ≈ 550 m
NightDayNightDayNightDay
321.254390.104318.828428.696288.191472.704
6' IKMTHU-RTCobb TrawlSimrad EK-60 38 kHz, avg Nautical Area Scattering Coefficients (m2•nmi-2)
Sampling Distribution:17 Cobb trawls19 IKMTs20 HU-RFTs
0.1
1
10
100
1000
Euphau
siace
a
Mysidac
ea
Decapoda
Stomatopoda
Oegopsid
a
Tunicata
Myctophidae
Total fish
Catch m
ass,
g/m2
Den
sity
(ind
.m-2
or g
wet
wt.m
-2)
cobb HN IKTNight sampling
IKMT
0.1
1
10
100
1000
Euphau
siace
a
Mysidac
ea
Decapoda
Stomatopoda
Oegopsid
a
Tunicata
Myctophidae
Total fish
Catch m
ass,
g/m2
Den
sity
(ind
.m-2
or g
wet
wt.m
-2)
cobb HN IKTNight sampling
Gear-types for Gear-types for intercomparison (what is intercomparison (what is micronekton?): micronekton?):
MIE-1 – “what one MIE-1 – “what one defines as micronekton defines as micronekton ≠ another”; enabled all ≠ another”; enabled all size range evaluation of size range evaluation of multiple acoustic multiple acoustic λλssMIE-2 – ‘appropriate’ MIE-2 – ‘appropriate’ gear of similar mesh gear of similar mesh sizes; standard gear sizes; standard gear (RMT 1+8, IKMT?); (RMT 1+8, IKMT?); towed acoustics (high towed acoustics (high frequencies)frequencies)
Opisthoproctus soleatus
Oplophorus gracilirostris
Abralia trigonura
What now?What now?
● Advances in technologyAdvances in technology● Signal strength (acoustics)Signal strength (acoustics)● Time series – observation systemsTime series – observation systems● Refined trophic linksRefined trophic links● Ecosystem rolesEcosystem roles