Review of Population Dynamics of Japanese Sardine in the Northwestern Pacific

Akihiko Yatsu, Masayuki Noto, Minoru Ishida, Hiroshi Nishida and Maki Suda

National Research Institute of Fisheries Science

• Distribution, migration and population dynamics

• Inter-annual and inter-decadal variations

• Possible factors causing these variations

• Existing models for Japanese sardine dynamics

Japanese Catch of Japanese Sardine, Anchovy, Mackerels and Jack during 1905-2001

Scomber: chub mackerel + spotted mackerel

0500,000

1,000,0001,500,0002,000,0002,500,0003,000,0003,500,0004,000,0004,500,0005,000,000

1905 1915 1925 1935 1945 1955 1965 1975 1985 1995

Cat

ch in

ton

(Sar

dine

)

0200,000400,000600,000800,0001,000,0001,200,0001,400,0001,600,0001,800,000

Cat

ch in

ton

(Oth

ers)

S ardineAnc ho vyS c o mbe rJac k mac ke re l

Distribution and migration of Japanese sardine and California sardine

Transition Zone

Sardine Biomass, Oyashio Southern Limit (OYSL) and Zooplankton Density in Oyashio and KOTZ

(Yatsu et al., in press Fish Oceanogr)

0

5,000

10,000

15,000

20,000

25,000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Bio

mas

s (1

000t)

050

100150200250300350400

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Densi

ty (m

g m

-3)

OY zooplankton

KOTZ zooplankton

34

36

38

40

42

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Lat

itude OYSL

•Sardine biomass increased with intensified Oyashio

•Intrusion of Oyashiowould enhance productivity

•But, ZP density was inversely related to Oyashio

•Predation by sardine (Tadokoro et al., in press Fish. Oceanogr.) : Sardine fed 32-138% of daily Neocalanusproduction in 1984

Kuroshio Transport, Kuroshio Northern Limit and Oyashio Southern Limit

20

40

60

80

100

120

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Tra

nsp

ort

(SV

)

KR Sverdrup transport

KR Geostrophic transport

34

36

38

40

42

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Lat

itude

OY southern limit

KR northern limit

Winter SST of Kuroshio Extension South Area (KESA) and Early Mortality Noto and Yasuda (1999, CJFAS)

Possible mechanistic linkIntensified vertical mixing in winter　⇒　Low winter SSTIntensified westerly wind ⇒　More transport of Oyashiowaters ⇒　Low SST

Survival of Feeding Larvae is the Key

0

2

4

6

8

10

12

1996 1998 2000 2002 2004

Recru

itm

ent

(bill

ion)

050100150200250300350400450

Abundan

ce indexRecruit

Index Fairly good relation indicate early survival is mainly determined after the feeding larvae distributing in Kuroshio and 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)

Correlation Coefficient (r) Map between Winter SSTand LNRR of Japanese Sardine (Yatsu et al., in press)

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

Extended Ricker Modelln RPS= -0.00017 SSB -1.59 KESASST + 30.68

-1

0

1

2

3

4

5

6

7

8

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

ln R

PS

Observed

Model

r2=0.37

RPS=Recruitment No. per Spawning Stock Biomass (SSB)

Correlation Map between OCTS/SeaWiFS Spring Chl-a and Japanese Sardine LNRR during 1996-2000

Saito (unpublished)

Days after hatching

(after Umeda 1996)Kuroshio Spec. Vol., 19

Mean total length (mm)

by prey density

Tank Exp

Kuroshio Extension and KOTZ as Key Areas of Sardine Recruitment: Implications of SST

• Vertical mixing and Intensified Oyashio - bottom up

• Stratification - timing of spring bloom • ZP species/size compositions• Growth of sardine larvae• More arrival of tropical tunas

and squids

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

1976 1981 1986 1991 1996 2001

Ski

p jac

k cat

ch (

May

-A

ug)

in N

ort

hern

Jap

an (

ton)

16.0

16.5

17.0

17.5

18.0

18.5

SST (

℃)

Skipjack catch

KESA winter SST

Days after hatching

(after Umeda and Iwasaki, 2001; Biocosmos Report)

Mean total length (mm) by temp.

Tank Exp

Prey Composition of Juvenile Small Pelagic Fishesand Myctophids (Adults & Juveniles) in May 2002

0% 20% 40% 60% 80% 100%

Myctophum asperum Juv.

Myctophum asperum Ad.

Myctophum nitidulum

Diaphus perspicillatus Juv.

Diaphus perspicillatus Ad.

Symbolophorus californiensis

Notoscopelus resplendens

Notoscopelus japonicus

Ceratoscopelus warmingii Juv.

Ceratoscopelus warmingii Ad.

Anchovy

Sardine

Spotted mackerel

Chub mackerel

Composition by number

Euphausiids

Neocalanus

Eucalanus

Metridia

Pleuromamma

Paracalanus

Corycaeus

Oncaea

CALANOIDA (broken)

Other COPEPODA

Salps

Oikopleura

Oikopleura house

Gelatinous

Eggs of Invertebrates

Fishes

Miscellaneous

Density-dependent Growth

0

20

40

60

80

100

120

140

160

180

1976 1981 1986 1991 1996

Mean

body

weig

ht

(g)

0

5000

10000

15000

20000

25000

Bio

mas

s (1

000t)

Age 0

Age 1

Age 2

Age 3

Age 4

Age 5

Biomass

If Fishing Mortality Coefficient F were Reduced

1

10

100

1,000

10,000

100,000

1985 1990 1995 2000

SS

B (

1000 t

)

Fishing control

Actual

Simulation by reduction of actual F by half after 1997, using observed RPS values

Transport and Survival Model from Spawning Ground to KE and KOTZ

(Kasai et al., 1997 Fish. Sci.)•Input 1: Egg distribution and abundance

•Input 2: Wind stress and Kuroshio transp.

•Input 3: Mortality rates day-1

0.5: offshore, 0.15: Kuroshio & coastal

step function in KOTZ

A Spatial "Individual" Based Model of Early Life(Suda and Kishida, 2003 Fish. Oceanogr.)

•Super-individual or Fish School = 1x1degree cell

Distribution of sardine larvae

after 40 days from spawning

A Spatial "Individual" Based Model of Early Life(Suda and Kishida, 2003 Fish. Oceanogr.)

•For each CELL

•Input 1: Egg census data

•Input 2: actual temperature, prey density and predator biomass for each area

• Survival and growth are both density-dependent and independent

A Spatial "Individual" Based Model of Early Life(Suda and Kishida, 2003 Fish. Oceanogr.)

Results: actual and simulated recruits

A Life history "Individual" Based Model(Suda et al., in preparation)

Spatial "IBM"Suda and Kishida

(2003)

Stock: VPA and growth

incorporating environment, predation andcompetitions

Spawning: spatially allocate

eggsSpawning

Stock Biomass

RecruitsEgg

•Input 1: Initial stock Status

•Input 2: temperature, prey density and predator biomass for each area

•Input 3: Observed spawning area

Effect of Fishing can be also evaluated

Summary• Reproductive success (RPS)= f {SSB (density effects),

SST of Kuroshio Extension, unparameterized factors (e.g., Oyashio, predators, competition with anchovy, nutrient condition of spawners)}

• Growth = f {density, water temperature, prey}• Biomass accumulation = f {

SSB, RPS, Growth, Survival (after recruit) }NB: intensive fishing may prevent stock recovery

• WSA Gyre and central NP are feeding grounds, only during high stock periods

• Possible combinations of NEMURO (PICES), Circulation Models (Kasai et al., 1997; Komatsu’s OGCM) and Spatial "IBM" (Suda et al., in prep.)

Basic Biology of Sardine and AnchovyJapanese sardine Japanese ancnovy

Life span about 7 yr about 3 yrMax size BL 25 cm 14 cm

Fist maturity age 1 (Low Stock) or3 (High Stock) 1

Fist maturity BL 17 cm 6 cm

Spawning season winter autumn and spring

Spawning area southern Honshu - Kyushu northern Honshu - Kyushu(also open ocean during HS)

Prey

phytoplankton (Diatom)and zooplankton (Calanus,

Oncea, Microsetta,Corycaeus, Paracalanus,

etc.)

zooplankton (Oncea,Microsetta, Corycaeus,

Eucalanus, Paracalanus,Oithona , etc.)

For ref.

• Only for reference

Predators of sardine during 1983-90 (Biocosmos Report)

Japanese sardine consumed by Bramajaponica, 1983-90 (Biocosmos Report)

Sardine survival and growth in tank exp.

Temperature

(after Umeda 1996)Kuroshio Spec. Vol., 19

Relative survival rate (Age 3 to 7 days)

Days after hatching

(after Umeda and Iwasaki, 2001; Biocosmos Report)

Mean total length (mm) by temp.

須田モデル

Locations of Spawning Ground

1960s-90sEstimated

fromEgg Census

Survey(Hiramoto, 1996)

Egg Distribution of Japanese Sardine

High stock periods:

Spawning grounds extend across Kuroshio current -> -> more transport to KE

Line: Kuroshio axis

Low stock periods:

Spawning grounds confined within inshore areas

Japanese Sardine Outbursts and Global Air Temperature since the 17th Century (Klyashtorin, 2002)

KESA Winter SST and Sardine Catchand Larvae/Juveniles Distribution (Noto, 2003)

KESA winter SST

Sardine catch

Arrows: Transportation and migration

Hatched: Distribution of survivors

Odate Project – On going

• Species composition of macro-zooplankton archived at TNFRI

A Spatial "Individual" Based Model of Early Life(Suda and Kishida, 2003 Fish. Oceanogr.)

Results: actual and simulated recruits

Flow chart

PDO, SOI, AO and Kuroshio

-8

-6

-4

-2

0

2

4

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Anom

aly

PDO winter

SOI winter

AO winter

AO negativeAO posAO negative

PDO positivePDO negative and La Nina dominant El Nino

AO positive

20

40

60

80

100

120

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Tra

nsp

ort

(SV

)

KR Sverdrup transport

KR Geostrophic transport