Akihiko Yatsu, Masatoshi Moku, Hiroshi Nishida, Kaori Takagi, Norio Yamashita and Hiroshi Itoh
description
Transcript of Akihiko Yatsu, Masatoshi Moku, Hiroshi Nishida, Kaori Takagi, Norio Yamashita and Hiroshi Itoh
Possible Ecological Interactions between Small-pelagic and Mesopelagic Fishes in the Kuroshio-Oyashio Transition Zone and Kuroshio
Extension in Spring
Akihiko Yatsu, Masatoshi Moku,
Hiroshi Nishida, Kaori Takagi,
Norio Yamashita and Hiroshi Itoh
Horizontal DistributionVertical DistributionStomach Contents
Survey Area (Spring)
Lantern Fish Migration: Myctophum asperum (left) and Symbolophorus californiensis (right)
After Sassa (2001)
Backgrounds and Purpose Kuroshio-Oyashio Transition Zone (KOTZ) and Kuroshio Extension (KE) are the key areas for recruitment of sardine, anchovy, and mackerel
Mortality of anchovy larvae in KOTZ-KE is mainly caused by predation by black snake mackerel (Nealotus tripes).
Biological interactions between juvenile small pelagics and myctophids may be possible because 1) myctophids are abundant in KOTZ and 2) both are zooplankton feeder
Seek for possible interaction between small pelagics and micronectonic mesopelagic fishes in KOTZ
Day Night
Small pelagics
Meso-pelagics
?
Surface Trawl Survey in Kuroshio/OyashioTransition Zone in Spring since 1996
Net opening diam.: 27m
Towing at: 3.5 knots at night
Typical towing depth: 0-30m
Tansyu Maru (499GT, 1800HP): -1999 Hokuho Maru (664 GT, 2200HP ) 2000-
CPUE (kg / 30 min tow) of Japanese Sardine and SST
2004
2001
2000
1996
1997
1998
1999
2002
2003
1000m and 3000m isobath
Emperor Sea Mt.
Survey Index of and Estimated Recruit No.
0
2
4
6
8
10
12
1996 1998 2000 2002 2004
Rec
ruitm
ent
(bill
ion)
050100150200250300350400450
Abu
ndan
ce in
dexRecruit
Index
0
5
10
15
20
25
30
35
40
45
1996 1998 2000 2002 2004
Rec
ruits
(10̂
5)
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
Sur
vey
inde
x
RecruitIndex
Chubmackerel
Sardine
Fairly good relation indicate early survival is mainly determined after the feeding larvae distributing in Kuroshio and KOTZ
1.E+071.E+081.E+091.E+101.E+111.E+121.E+131.E+141.E+151.E+16
78 80 82 84 86 88 90
Year class
Pop
ulat
ion
num
bers
Egg
Yolk- saclarvae
Feedinglarvae
Recruit
Sardine (Watanabe et al., 1995)
CPUE kg/ 30min
0 10 20 30 40
Anchovy adult
Miscellaneous
Myctophids (juv.+ad.)
Sharks
Anchovy larvae
Neon flying squid
Club-hook squid
Common squid
Spotted mackerel ad.
Mackerel larvae
Sardine
Chub mackerel ad.
Catch WeightComposition in 2002
(0-30m depth)
Club-hook squid
Enoploteuthidae
Anchovy larvae Myctophids
Scomber juv. Jack juv.
2002Symbolophoruscaliforniensis
Ceratoscopeluswarmingii
Myctophumasperum
Diaphusperspicillatus
others
2003
Symbolophoruscaliforniensis
Ceratoscopeluswarmingii
Myctophumasperum
Diaphusperspicillatus
others
Adult Myctophid Biomass Composition in 2002 and 2003 (0-30m depth)
CPUE (kg / 30 min tow) of Small Pelagic Fishes and Myctophids (juv+ad) in 2000
Sardine
juv
Scomber spp. juv
Anchovy
larvae
Symbolophorus californiensis
Ceratoscopelus warmingii
Myctophum asperum
Diaphus perspicillatus
1000m and 3000m isobath
SST
Anchovy.
050
100150200250
0 25 50 75 100 125 150
Body length (mm)
0
1000
2000
3000
0 20 40 60 80 100 120 140
0
1000
2000
3000
0 20 40 60 80 100 120 140
0200400600800
1000
0 20 40 60 80 100 120 140
0100200300400500
0 20 40 60 80 100 120 140
0+
1+ 2+~
2+
0+ 1+
0+ 1+
1+ S. californiensisN = 11,266
C. warmingiiN = 8,281
M. asperumN = 4,453
D. perspicillatusN = 1,895
Scomber spp.
0102030405060
0 25 50 75 100 125 150
Fork length (mm)
J apanese sardine
0
2
4
6
8
0 25 50 75 100 125 150
Fork length (juv.) or Body length (ad.) (mm)
Size Composition ofSmall Pelagic Fishes and Myctophids in 2002
Juv. Sardine ad.
Scomber spp. Juv.
Larvae+Juv. (black) and adults (blue)
Symbolophorus californiensis
Ceratoscopelus
warmingii
Myctophum asperum
Diaphus perspicillatus
Standard length (mm)
Anchovy
Nighttime Vertical Distribution of Small Pelagics, Myctophids and Black Snake Mackerel in May 1995 at 37N 147E
Black Snake Mackerel Nealotus tripes as a Predator
Fi (%)
-60
-40
-20
0
20
40
60W
i (%)
Ci (
%) Unidentified fishes(1,699)
Euphausiids(2,399)
Myctophids(1,767)
Miscellaneous(702)
Anchovy larvae(543)
Squids(390)
Scomber(3)
150-220mm SL N=270
50 250100 150 20020
40
60
Fi %()
-60
-40
-20
0
20
40
60
Wi (
%)
C
i (%)
Unidentifiedfishes(1,862)
Euphausiids(1,826) Myctophids
(164)
Miscellaneous(1,009)
Anchovy larvae(163)
Squids(209)
Scomber(54)
70 - 149 mm SL N = 223
20
40
60
20 40 60 80 100 120 140 160
Index of Relative
Importance of Diets of
Black Snake
Mackerel in May 2002
Larvae BSM selectively feeds on anchovy larvae (Kubota ,2003)
Subadults
Adults
Freq
% in Weight
% in No.
Prey Composition of Juvenile Small Pelagic Fishes and Myctophids (Adults & Juveniles) in May 2002
0% 20% 40% 60% 80% 100%
Myctophum asperum J uv.
Myctophum asperum Ad.
Myctophum nitidulum
Diaphus perspicillatus J uv.
Diaphus perspicillatus Ad.
Symbolophorus californiensis
Notoscopelus resplendens
Notoscopelus japonicus
Ceratoscopelus warmingii J uv.
Ceratoscopelus warmingii Ad.
Anchovy
Sardine
Spotted mackerel
Chub mackerel
Composition by number
EuphausiidsNeocalanusEucalanusMetridiaPleuromammaParacalanus CorycaeusOncaeaCALANOIDA (broken)Other COPEPODASalpsOikopleuraOikopleura houseGelatinousEggs of InvertebratesFishesMiscellaneous
Stomach Contents of Sardine and Prey Availability in Kuroshio Extension during 1997-1998 (Saito et al., 2001)
Small copepods (<0.8mm BL, Paracaranus etc.) are abundant
Large copepods (Calanus pacificus etc.) was less abundant
Optimum prey size for juvenile sardine (25-40mm BL) is 0.8-1.2mm
Juvenile sardine (>33 mm BL) selectively fed on large copepods
Larval sardine (26-31 mm BL) preyed upon small copepods
Juveniles of both myctophids and small pelagics fed on 0.6-0.9 mm BL Paracalanus in KOTZ (our results)
Size of prey (μm)
Prey density (ind m-3)
Summary Juvenile small pelagics and myctophids (ad.+juv.) horizon
tally overlap in surface waters (0-30m) of KOTZ in spring Black snake mackerel shift their diet from anchovy larvae,
to krill and myctophids with ontogenetic descent Corycaeus and Oncea (epipelagic) were preyed by juvenil
es of small pelagics and some juvenile myctophids Krill, Pleuromamma and Metridia (deil vertical migrants wi
th photophores) were exclusively consumed by myctophids
Possible competition for large copepods Further studies are needed for 1) competition with juvenile myctophids for epipelagic ZP,
2) indirect effects of black snake mackerel, 3) quantitative evaluation
SpawningStock Biomass
and Recruitment
of Sardine
and Chub mackerel
R per SSB =f (SSB, SST
in key areas) but imperfect
050,000
100,000150,000200,000250,000300,000350,000
0 5,000 10,000 15,000SSB (1000t)
Rec
ruitm
ent
(mill
ion) 80
86
77
88
Sardine
0
5,000
10,000
15,000
20,000
25,000
0 1,000 2,000 3,000 4,000SSB (1000t)
Rec
ruitm
ent
(millio
n)
64
67
71
79
63
77
85
69
66
Chub mackerel
Myctophids: Diel Vertical Migration and Feedingin Oyashio Area (Moku et al., 2000)
Prey Composition of Juvenile Small Pelagic Fishes and Myctophids (ad.+juv.) in May 2002
0% 20% 40% 60% 80% 100%
Myctophum asperum
Myctophum nitidulum
Diaphus perspicillatus
Symbolophorus californiensis
Notoscopelus resplendens
Notoscopelus japonicus
Ceratoscopelus warmingii
Anchovy
Sardine
Spotted mackerel
Chub mackerel
Composition by number
EuphausiidsNeocalanusEucalanusMetridiaPleuromammaParacalanus CorycaeusOncaeaCALANOIDA (broken)Other COPEPODASalpsOikopleuraOikopleura houseGelatinousEggs of InvertebratesFishesMiscellaneous
CPUE (catch weight per a tow) of Small Pelagic Fishes and Myctophids (juv+ad) in 1999
Sardine
Juv.
Scomber spp. Juv.
Anchovy
larvae
Symbolophorus californiensis
Ceratoscopelus warmingii
Myctophum asperum
Diaphus perspicillatus
1000m and 3000m isobath
SST