The vertical and horizontal distribution of bigeye tuna ... · 14th PICES The vertical and...

14th PICES

The vertical and horizontal distribution of The vertical and horizontal distribution of bigeyebigeye tuna (tuna (ThunnusThunnus obesusobesus) and ) and

yellowfinyellowfin tuna (tuna (ThunnusThunnus albacaresalbacares) related ) related to ocean structureto ocean structure

Eun Jung Kim 1,2, Suam Kim1, Dae-Yeon Moon2 and Jeong-Rack Koh2

1Pukyong National University2National Fisheries Research & Development Institute

Eun Jung Kim 1,2, Suam Kim1, Dae-Yeon Moon2 and Jeong-Rack Koh2

1Pukyong National University2National Fisheries Research & Development Institute

IntroductionIntroduction

The tuna fishing area in the Tropical Pacific

Longline Fishing area

NINO3.4Warm pool High density areaPurse seine fishing area

depth

Schematic vertical distribution of tuna species in Pacific

W170E130 E150 E170

Skipjack tuna & environmental factors

Bigeye tuna

(Thunnus obesus)

Yellowfin tuna

(Thunnus albacares)

ObjectiveObjective

To find the response of spatial & vertical distribution of bigeye &

yellowfin tuna related to the oceanographic condition

Horizontal distribution

of bigeye and yellowfin tuna

Horizontal distribution

of bigeye and yellowfin tuna

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Materials & MethodsMaterials & Methods

FISHING AREAFISHING AREA

Fishing data

• About 200 Korean longline vessels

• Jan. 1999 –Dec. 2000

• Catch numbers of bigeye and yellowfin tuna

georeferenced in 5° grids of latitude and longitude.

• Fishing gravity centre of CPUE(G) in month j

Gj = ∑iLi(Cij/Eij)/∑i(Cij/Eij)

ResultsResults

170W 160W 150W 140W 130W

5N

5S

0

1999 sep-nov

1999-2000 dec-feb

2000 march-may1999 jun-aug

2000 sep-nov

1999 mar-may2000 jun-aug

170W 160W 150W 140W 130W

5N

5S

02000 jun-aug 1999 mar-may

1999 jun-aug

1999 sep-nov

1999-2000 dec-feb

2000 march-may

2000 sep-nov

Seasonal change (3 months) of fishing centroids

Yellowfin tuna

Bigeye tuna

ResultsResults

Monthly change of centroids

Longitudinal centroids Latitudinal centroids

170

180

190

200

210

220

230

240

Jan-

99

Mar

-99

May

-99

Jul-9

9

Sep-

99

Nov

-99

Jan-

00

Mar

-00

May

-00

Jul-0

0

Sep-

00

Nov

-00

-6

-4

-2

0

2

4

r=0.449 (<0.05)

yellowfin

bigeye 4N2N

02S4S6S

130W

150W

170W

170E

Jan-

99

Mar

-99

May

-99

Jul-9

9

Sep-

99

Nov

-99

Jan-

00

Mar

-00

May

-00

Jul-0

0

Sep-

00

Nov

-00

Not significant

yellowfin

bigeye

What causes this change?

190

195200

205

210

215220

225

230

1999

-01

1999

-03

1999

-05

1999

-07

1999

-09

1999

-11

2000

-01

2000

-03

2000

-05

2000

-07

2000

-09

2000

-11

23

24

25

26

27

28

190

195

200

205210

215

220

225

230

1999

-01

1999

-03

1999

-05

1999

-07

1999

-09

1999

-11

2000

-01

2000

-03

2000

-05

2000

-07

2000

-09

2000

-11

23

24

25

26

27

28

Yelloiwfin tuna

Longitudinal centroid of bigeye

SST in NINO3.4SST in NINO3.4

Longitudinal centroid of yellowfin

Not significantr=-0.465 (<0.05)

ResultsResults

150W

160W

170W

140W

130W

W

150W

160W

170W

140W

130WE

(C°) (C°)W

E

Longitudinal centroids & SST of NINO3.4

Bigeye tuna

ResultsResults

170W 160W 150W 140W 130W

5N

5S

0

1999 sep-nov

1999-2000 dec-feb

2000 march-may1999 jun-aug

2000 sep-nov

1999 mar-may2000 jun-aug

170W 160W 150W 140W 130W

5N

5S

02000 jun-aug 1999 mar-may

1999 jun-aug

1999 sep-nov

1999-2000 dec-feb

2000 march-may

2000 sep-nov

Seasonal change (3 months) of fishing centroid

Yellowfin tuna

Bigeye tuna

ResultsResults

Anomaly of SOI (Southern Oscillation Index)with longitudinal centroids

-15

-10

-5

0

5

10

15

20

Jan-99

Mar-99

May-99

Jul-99

Sep-99

Nov-99

Jan-00

Mar-00

May-00

Jul-00

Sep-00

Nov-00

SOI

Longitude

190

195

200

205

210

215

220

225

230

170W

160W

150W

140W

130W

W

E

Vertical distribution

and yellowfin tuna

Vertical distribution

and yellowfin tunaof bigeyeof bigeye

Materials & MethodsMaterials & Methods

Schematic view of a “basket” of tuna longline gear

Sea surfaceFloat line→

Main line→

Branch line→

↑hook

Float

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Materials & MethodsMaterials & Methods

FISHING AREAFISHING AREA

Fishing data

• One fishing vessel, Sinyoung 53

• August 1999 – October 2000

• Catch per hook of 211 sets of longline setting

Materials & MethodsMaterials & Methods

to calculate the depth of each hook…

Yoshihara formula (1951,1954)Dj=ha+hb+L{(1+cot2φ˚)1/2-[(1-2j/n)2+cot2φ˚]1/2}

No. of

hook

1(17)

2(16)

3(15)

4(14)

5(13)

6(12)

7(11)

8(10)

9

Depth

(m)131 164 207 247 286 322 351 372 379

120-190m 191-260m 261-330m 331-400m

Materials & MethodsMaterials & Methods

Environmental data (TAO buoy data)(http://www.pmel.noaa.gov/tao/index.html)Subsurface temperature (0-500m)

ResultsResults

CPUEs of bigeye and yellowfin tuna in four depth

(No. of fish/1000 hooks)0 3 6 9

120-190m

191-260m

261-330m

331-400m

yellowfin bigeye

1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

160W 150W 140W 130W

160W 150W 140W 130W160W 150W 140W 130W-500

-400

-300

-200

-100

-500

-400

-300

-200

-100

-500

-400

-300

-200

-100

-15

-10

-5

0

5

10

15

20

Jan-99

Mar-99

May-99

Jul-99

Sep-99

Nov-99

Jan-00

Mar-00

May-00

Jul-00

Sep-00

Nov-00

SOI anomalyAugust – September, 1999

May – August, 2000October – April, 1999-2000

SummarySummary

Spatial distribution with season was not clear, but catch locations of both species look coherent longitudinally.

Bigeye tuna seem to distribute further east than yellowfin tuna.

El Niño might affect on the longitudinal fishing grounds of both species. However, yellowfintuna response more sensitively to the environmental change than bigeye tuna.

SummarySummary

Bigeye tuna located in deeper depth than yellowfin tuna.

When the SOI was negative (i.e., thermoclinewas shallow in the western area), the tuna distributions seemed to be located more in the western area, and vice versa.

The vertical movement was not clear from our study.

Future studyFuture study

Use of more vertical data over longer

period

Investigation on distribution of several

tuna species under dynamical ocean

structure

Part 3.Part 3.

Bait selectivityBait selectivity

Materials & MethodsMaterials & Methods

Bait were used…

Mackerel

Horse mackerel

Squid

Sardine

Herring

Results & Discussion

0

0.2

0.4

0.6

0.8

1

mackerel horsemackerel

squid sardine herring

fish/

100

baits

bigeye yellowfin

ResultsResults

7.2

7.2

5.4

2

8.4

9

6.9

3.6

4.6

6.8

5.9

1.8

7.3

8.9

6.3

4.3

6.2

8.4

2.7

2.1

0 10 20 30 40 50

330-400m

260-330m

190-260m

120-190m

mackerel horse mackerel squid sardine herring

Bait selectivity of bigeye tuna

(no. of fish/1000 bait)

ResultsResults

2.5

5.7

5.2

3.7

5.1

6.1

6.4

9.3

2.4

4.1

4.3

3.1

5.2

5.4

5.8

4.9

3.1

3.3

4.6

4.2

0 10 20 30 40

330-400m

260-330m

190-260m

120-190m

mackerel horse mackerel squid sardine herring

Bait selectivity of yellowfin tuna

(no. of fish/1000 bait)

SummarySummary

Sardine and horse mackerel are the efficient bait for bigeye and yellowfintuna.

The order of bait efficiency is not change even the depth difference in both species.