Distribution and Population Dynamics of Japanese Sardine ...Sardine flourish 16.2ºC 22.0ºC...
Transcript of Distribution and Population Dynamics of Japanese Sardine ...Sardine flourish 16.2ºC 22.0ºC...
Distribution and Population Dynamics of Japanese Sardine, Anchovy and Chub
Mackerel in the Kuroshio/Oyashio System: Seeking for Mechanistic Responses to
Regime Shifts
Akihiko Yatsu1, Hiroshi Kubota1, Akinori Takasuka1, Motomitsu Takahashi2, Norio Yamashita1, Hiroshi
Nishida1, Chikako Watanabe1, and Yoshioki Oozeki1
1 National Research Institute of Fisheries Science, Japan2 Integrative Oceanography Division, Scripps Institution of Oceanography, USA
Recent Distribution of Japanese Sardine, Anchovy, Mackerels in the Northwestern Pacific
Sardine (Low Stock) Anchovy (High Stock) Chub mackerel
Distribution
=Feeding gr.
Spawning ground
Distribution
Spawning ground
Feeding ground
Distribution
=Feeding ground
=Spawning ground
3 species share common feeding ground and to some extent spawning ground
Anchovy spawning and feeding grounds are overlapping
Japanese Catch of Japanese Sardine, Anchovy, Mackerels during 1905-2001
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
1905 1915 1925 1935 1945 1955 1965 1975 1985 1995
Cat
ch in
ton
(Sar
dine
)
0
500,000
1,000,000
1,500,000
2,000,000
Cat
ch in
ton
(Anc
hovy
, M
acke
rels
)SardineAnc hovyMac ke re lsRe g ime s hift
Mackerels: chub mackerel + spotted mackerel
Regime shift years: after Yasunaka and Hanawa (2002) excl. 1998/99
Alternation of 3 species in a decadal scale is probably related to climatic regime shifts
Locations of Spawning Ground of Japanese
Sardine during1960s-90sEstimatedfrom the
Egg CensusSurvey
(Hiramoto, 1996)
Expand beyond Kuroshio during high stock period, but not to KOTZ
Kuroshio
Egg Distribution of Japanese Anchovy (Zenitani and Kimura, 1997)
Expand to KOTZ during high stock period, but not south of Kuroshio
Kuroshio
KOTZ
Driftnet CPUE at 155E during June, 1976-1999, by Hokkaido University
マイワシ
32.5
35.0
37.5
40.0
42.5
45.0
75 80 85 90 95 100
Year
緯度
(N
)
= 5000
= 1000= 200= 50
カタクチイワシ
32.5
35.0
37.5
40.0
42.5
45.0
75 80 85 90 95 100
西暦
緯度
(N
)
= 5000
= 1000= 200= 50
マサバ
32.5
35.0
37.5
40.0
42.5
45.0
75 80 85 90 95 100
西暦
緯度
(N
)
= 5000
= 1000= 200= 50
Sardine
Anchovy
Chub mackerel
Year (1900+)
Year (1900+)
Latit
ude
(N)
Latit
ude
(N)
Latit
ude
(N)
Driftnet monitoring sites at 155E
Adult distribution expand to open ocean
during high stock period, in the 3 species
Basic Biology Japanese sardine Japanese anchovy Chub mackerel
Life span about 7 yr about 3 yr 7 yr or moreMax size BL 25 cm 14 cm 40 cm
Fist maturity age(year)
1 (Low Stock) or3 (High Stock) 1 2 (Low Stock) or
3 (High Stock)
Fist maturity BL 17 cm 6 cm 30 cm
Spawning season winter spring-autumn spring
Spawning area
southern Honshu -Kyushu
(expand to open ocean beyond Kuroshio in the
High Stock period )
northern Honshu -Kyushu
(expand to open ocean in KOTZ in the High
Stock period)
central Honshu - Kyushu
Prey
phytoplankton (Diatom) and zooplankton
(Calanus, Oncaea, Corycaeus,
Paracalanus)
zooplankton (Oncaea, Microsetella,
Corycaeus, Eucalanus, Paracalanus, Oithona)
zooplankton (Neocalanus, Eucalanus, Krill),
anchovy, squid, salps
Correlation Coefficient (r) Map between Winter SSTand LNRR of Japanese Sardine (Yatsu et al., 2005)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
0 5000 10000 15000
SSB (1000t)
Recru
itm
ent
(10^6
) 80
86
77
88
LNRR=
ln (Recruitment Residuals)
Ricker curve
●: positive r
○: negative r
KESA
36
38
40
42
-4 -2 0 2 4
PDO
OYSL
OYSL: Oyashio (1st br.) Southern Limit
Correlation Coefficient (r) Map between Winter SSTand LNRR of Chub Mackerel (Yatsu et al., 2005)
0
5,000
10,000
15,000
20,000
25,000
0 1,000 2,000 3,000 4,000
SSB (1000t)
Recru
itm
ent
(mill
ion)
64
67
71
79
63
77
85
69
66
Chub mackerel
LNRR=
ln (Recruitment Residuals)
Ricker curve
●: positive r
○: negative r
Principal spawning grounds
KOTZ: Key Area for Recruitment
Early survival is mainly determined after the feeding larvae distributing in KOTZ
1.E+07
1.E+08
1.E+09
1.E+10
1.E+11
1.E+12
1.E+13
1.E+14
1.E+15
1.E+16
78 80 82 84 86 88 90
Year class
Popu
lation n
um
bers
Egg
Yolk-saclarvae
Feedinglarvae
Recruit
Watanabe et al. (1995)
0
20
40
60
80
100
120
140
1996 1998 2000 2002 2004
Recr
uitm
ent
(10 m
illio
n)
0
1
10
100
1,000
Pre
-re
cru
itm
ent
Ind
exRecruitment
Index
KOTZ
Sardine
Sardine
0
10
20
30
40
50
1996 1998 2000 2002 2004
Rec
ruitm
ent
(10 m
illio
n)
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
Pre
-re
crui
tmen
t In
dexRecruitment
Index
Chub mackerel
Cladocera75% 76%
Sardine Anchovy
N=12, SL=30.4-47.5mm N=5, SL=32.2-40.7mm
Calanus spp.
Corycaeusspp.
Paracalanus spp.
Small Calanoida(PL < 1mm)
Phytoplankton
Oncaeaspp.
Unidentified plankton
Other large copepod
Other small copepod
4.9%
8.1%6.2%
7.6%
5.0%3.0%
2.6%
Oncaeaspp.
Large Calanoida(PL < 1mm)Large
Calanoida(PL < 1mm)
Prey Composition (in No.) of Juvenile Sardine and
Anchovy in KOTZ (May, 1997; Kubota et al., unpublished)
Cladocera and some copepods were common prey
Growth Rate Comparison between Simultaneously Collected Sardine (Gms) and Anchovy (Gma) in
KOTZ (Takahashi et al., PICES XIII 2004)
Gm
s(m
m d
-1)
1997
Gma (mm d-1)
1998
1999
2000
2001
2002
( )
Gms = -1.99 Gma + 2.09(n=5, r=0.84, P = 0.078)
0.4
0.6
0.8
1
0.4 0.6 0.8 11.0
1.0
Poor prey
Sardine Anchovy
Direct effect of temperature on early growth and, hence early survival if prey is sufficient in KOTZ
‘Optimal Growth Temperature’ Hypothesis(Takasuka et al., PICES XIII 2004, submitted)
10 15 20 250
0.2
0.4
0.6
0.8
1.0
Sea surface temperature (°C)
Gro
wth
rat
e (m
m d
ay–1
)
AnchovySardineAnchovySardine
10 15 20 250
0.2
0.4
0.6
0.8
1.0
Sea surface temperature (°C)
Gro
wth
rat
e (m
m d
ay–1
)
AnchovySardine Temperature shift
AnchovyAnchovy flourishSardineSardine collapse
AnchovyAnchovy collapseSardineSardine flourish
16.216.2ººCC 22.022.0ººCC
Different optimum SSTs for early growth were detected in sardine and anchovy collected from various areas and years in the NW Pacific, leading to a plausible hypothesis of regime shift
Early Growth of Chub Mackerel in KOTZ and Recruitment-per-Spawners (RPS) during 2003-2005
(Yamashita et al., unpublished)
0
5
10
15
20
1.00 1.25 1.50 1.75
Growth Rate(mm/day)
RPS (Num
ber/
kg)
2004
2005
2003
0
20
40
60
80
100
0 20 40 60Age (day)
Fork
lengt
h (m
m)
2003(n=32)
2004(n=27)
2005(n=77)
(RPS isTentative value)
Early growth may also be a key for survival of juveniles of chub mackerel --- needs more data
Prey Composition of Skipjack Tuna (2004)(Watanabe et al., unpublished)
April-May 2004 June-August 2004 June-August 2004
Kuroshio Kuroshio KOTZ
Num
ber (
%)
Wei
ght (
%)
Fishes
Frequency (%)
FishesFishes
AnchovyAnchovy
Anchovy
Amphipods
AmphipodsAmphipodsSquids
Squids
Misc
Misc
Decapods
SKJ heavily prey upon anchovy larvae and adults in recent years
Skipjack Catch (1968)
http://ss.myg.affrc.go.jp/tnf/news07/kasahara.htm
May
June
Skipjack Recruitment Anomaly in the
Western North Pacific(Inagake et al., 2005, Enyo
News 116)
More arrival of SKJ since the 1980's but anchovy larvae is less vulnerable to SKJ than sardine
and chub mackerel, due to expanded spawning area to
KOTZ
Migration and InteractionSpawningNursery
Winter
Sardine Anchovy Chub mackerel
Spring
Skipjack
WinteringFeeding
• Predation by skipjack (Kuroshio: Winter, KOTZ: Spring)• Predation of anchovy by chub mackerel (Kuroshio & KOTZ: Spring)• Competition for small copepods between sardine and anchovy (KOTZ)• Less vulnerability of anchovy larvae to skipjack (Kuroshio: Winter)
KOTZ
Kuroshio
Ecosystem Connectivity and Regime Shifts(Bakun and Broad (eds) 2002, Climate and Fisheries)
FIGURE 4. Ecosystem Connectivity. Reproductively isolated local populations may be indirectly connected via a shared resource (i.e., “bottom-up
connectivity”) or a shared predator or fishery (i.e.,“top-down connectivity”). Climatic shifts may affect any of these ecosystem levels.
Sardine Anchovy
Summary: Implications of Temperature and Food Web for the 3 Species in KOTZ
Food web Food web • Direct consumption
of anchovy by chub mackerel
• Possible competition for small copepods between sardine and anchovy
• Less vulnerability of anchovy larvae to skipjack
SSTSST• Vertical mixing and strength
Oyashio - bottom-up• Stratification - timing of spring
bloom • ZP species/size compositions• Growth and survival of larvae • Contact to skipjack (and
squids); higher mortality when SST is high - top-down
Unanswered question: Evolution of different life-histories, particularly between sardine and anchovy