to climatic regime shifts?

Transcription

1 Can we explain and predict stock fluctuations of Japanese common squid, Todarodes pacificus related to climatic regime shifts? Yasunori SAKURAI 1, Jun YAMAMOTO 2, Ken MORI 3 Tsuneo GOTO 4 and Hideaki KIDOKORO 4 1 Graduate School of Fisheries Sciences, Hokkaido University, 2 Hakodate Branch, Field Science Center for Northern Biosphere, Hokkaido University 3 Hokkaido National Fisheries Research Institute 4 Japan Sea National Fisheries Research Institute

2 Background Recruitment success in squids depends largely on environmental conditions at the spawning and nursery grounds Stock size in Japanese common squid, Todarodes pacificus might fluctuate due to environmental factors such as the winter wind stress, air temperature, and mixed layer depth at the spawning grounds. Objective How to predict stock fluctuation of common squid related to climate change, based on the new reproduction and recruitment scenario.

3 N Autumn-spawning group 40 Feeding migration (Apr ~Aug) Spawning migration(sep ~Nov) Winter-spawning group 30 Spawning area (Oct ~ Dec) E 30 Spawning area (Jan~Mar) Feeding migration (Jun~Dec) Spawning migration (Nov~Jan) E Spawning grounds and migration routes of T. pacificus

4 Warm Regime Cool Regime Warm Regime Japan + Korea The Sea of Japan Pacific Catch (x 1,000 t) Annual fluctuation in common squid, T. pacificus catches of Korea and Japan during (Data derived from the Japan Sea Research Institute, Japan and the National Fisheries Research and Development Institute, Korea).

5 Regime shift Sea surface temperature anomaly in February (Noto & Yasuda, 1999)

6 S September Warm Regime October 400, ,000 Routes of spawning migration based on the release & catch data of tagged squids Korea Japan Sea of Japan Catch (t) 200, S September Cool Regime October 100, , , Catch (t) 200, , Kidokoro (Pers. Com.)

7 S September Warm Regime October ?? Routes of spawning migration based on the release & catch data of tagged squids 漁獲量 ( トン ) 400, , , ,000 0 韓国日本日本海 ( 日本漁船 ) Kidokoro (Pers. Com.)

8 ~ ~ No data 1980s 1990s Changes of distribution patterns of T. pacificus paralarvae of autumn spawning group in 1980 s (cool regime) and 1990 s (warm regime). (No. of paralarvae/tow). (T. Goto et al., 2005)

9 abundance 曳網点当たり平均採集個体数 of T. pacificus paralarvae Cool regime Warm regime CPUE 沖合漁獲量 (kg/day) (- -) Fig. Annual changes of abundance of T. pacificus paralarvae / 1000m 3 (Oct-Nov) and CPUE (kg/day, May-Oct, Japan Sea) (Goto et al, 2002)

10 Stock fluctuations of Japanese common squid ( (Todarodes related to climate change Todarodes pacificus) *How do climatic changes affect stock size through the reproduction and recruitment process? Is it sea water temperature, wind stress or MLD? *How do changes of wind stress, sea and air temperature or MLD affect the success of reproduction?

11 Weak wind stress Strong wind stress Shallow MLD Deep MLD Warm water Warm water No survival eggs cold water Continental slope Continental slope cold water

12 Natural egg mass survey using ROV ROV ( Expert Nova System, KOWA Co.Ltd. ) Equipments : Two pairs of thrusters Horizontal and Vertical 3 Cameras 3CCD,video and 35-mm Capacity to resist depth : 400m Horizontal thruster Vertical thruster 水温躍層 3CCD camera Video camera 35mm film camera Schema of ROV observation

13 128E 128E 129E 129E 130E 130E 131E 131E 33N 33N 34N 34N 35N 35N 36N 36N E 128E 129E 129E 130E 130E 131E 131E 33N 33N 34N 34N 35N 35N 36N 36N Korea Japan Busan Fukuoka N E Depth 122m 18 Oct. 2003

14 Gelatinous sphere mass resembling T. pacificus egg mass observed by J. Yamamoto (Depth:80m, Temp:21,Oct. 18, 2003) Animation disengaged

15 Gelatinous sphere mass resembling T. pacificus egg mass (Depth:80m, Temp:21,Oct. 18, 2003) Egg mass of T. pacificus in captivity

16 Operation #1 (Otc.18) Temperature ( o C) T D S salinity Density (σ t) Vertical hydrographic features at the ROV station The egg masses of T. pacificus are thought to occur within or above the pycnocline at temperatures suitable for egg development (15-23 ) However, we found a jelly-like mass at 21, not in cold water.

17 Survey areas for meteorological and MLD analysis Dec Dec Jan Feb

18 weak 勢力弱 勢力強 strong -2 5Yrs mean raw Annual 図 4. change アリューシャン低気圧 of Aleutian low pressure index. (Nakamura and Honda, 2002)

19 Sea surface temp.( ) 12.0 Catch of winter cohort Wind speed at sea surface Feb Year Wind Sp d (m/s)

20 stage2 stage2 stage2 stage3 0 stage3 stage3 2 stage3 3 What development stage can hatchlings ascend from near thermocline to the surface in the same temperature range of for normal embryonic development? (Miyanaga et. al., 2006) Development stage of hatchling (Watanabe et al., 1996)

21 30cm 1.5m 2m Measurement of vertical swimming speed of hatchling at different development stage and temperature (15-23 ) ) using a transparent columnar tank.

22 Swimm ing rate (% ) Stage 30 n=291 n=422 n=59 n=188 n=30 n=390 n=124 n= Rearing temperature ( o C) n=45 Stage 31 n=205 n=78 n=25 n=239 n=481 n=57 n= Rearing temperature ( o C) ND ND Stage 32 n=30 n=74 n=143 n=124 n=20 n= Rearing temperature ( o C) For paralarvae reared at , swimming rates were higher at stage 31 than at stage Swimming began at stage 31.

23 Fair and high survival of eggs and hatchlings occur at 18-23, and , and can survive at the surface layer of 24. Hatch occurs at stage Hatchlings stay near the egg mass by stage 30 and ascend to sea surface after stage 31 within one day from a few hundred meters in deep o C 16 o C 18 o C 18.5 o C 19.5 o C 23 o C 24 o C Fair High survival survival Surface No survival Swim upward at stage 31 Hatch at stage 30 Pycnocline Reach the surface within one day

24 High survival of hatchlings: >25 <24 >18 < 18 < 18 New Schematic view of reproductive processes of T. pacificus

25 Occurrence of T. pacificus hatchlings (<1mm DML) at the sea surface layer in the East China Sea, February 2001 (Sakai et. al., 2006) ;100ind./1000m 3 (1mm> palararva)

26 Inferred spawning areas of winter cohort of T. pacificus (orange ) and distribution of hatchlings (< 1mm DML) during (Sakai et. al., 2006) m 500m Inds/ < < 200 < 100 < 50 < 10 0 No data No data

27 Hatchlings will be transported northeastward by the inner current of Kuroshio along the continental edge and trapped in Kuroshio frontal eddies. (Sakai et. al., 2006) Tsushima Current Transport Spawning and Hatching

28 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML<1.0mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

29 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML<1.5mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

30 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML<2.0mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

31 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML<3.0mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

32 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML<5.0mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

33 Distribution patterns of T. pacificus hatchlings ranged from 1 mm to 5 mm DML Feb., 2001 DML 5.0mm : > 250> 50> 100> (K. Mori, Ph.D. Thesis, Hokkaido University,2006)

34 Inferred spawning area of T. pacificus during recent years, (winter cohort). 30 Spent squids caught on the bottom 200m Continetal shelf and slope 19 Front of the coastal cold water 2knots 5days Occurrence of hatchlings (<1mm DML) Kuroshio 25 Inferred spawning ground (Modified from K. Mori, Ph.D. Thesis, Hokkaido University,2006)

35 During warm regime Winter wind stress (weak) Sea surface air temperature (high) >24 o C Egg mass 18 o C~23 o C ( o C) Spawning <17 o C Pycnocline <17 o C Hatch Continental shelf and slope (adapted from Sakurai et al.,2000)

36 Start of cool regime Winter wind stress (gradually strong) Sea surface air temperature(low) Egg mass Spawning >24 o C <17 o C 18 o C~23 o C ( o C) Pycnocline <17 o C Hatch Egg mass (broken?) No hatch Continental shelf and slope (adapted from Sakurai et al.,2000)

37 During cool regime Winter wind stress (very strong) Sea surface air temperature(low) Spawning >24 o C 18 Egg C~23 mass C <17 o C ( o C) Pycnocline <17 o C Hatch Egg mass (broken?) No hatch Continental shelf and slope (adapted from Sakurai et al.,2000)

38 mid-october, 2005 mid-november, 2005 mid-december, 2005

39 mid-october, 2005 mid-november, 2005 mid-december, 2005 mid-january, 2006 mid-february, 2006 mid-march, 2006

40 100 m 500 m

41 Catch (10 5 t) Anchovy, Jack mackerel Spawning temperature index (11-term running mean) Japanese anchovy Jack Results mackerel 5 Japanese anchovy Anchovy Sardine Jack mackerel Common squid Year Mackerel Japanese sardine Sardine Catch fluctuations of main pelagic species for fisheries in Japan 谷津 (2003) Mackerel Mackerels Jack mackerel Anchovy Sardine, Mackerel Japanese common squid Anchovy Sardine Mackerel Jack mackerel Sea surface temperature ( C) Similarities and differences in spawning temperature patterns represent those in the long-term population dynamics patterns. (Takasuka, 2006)

42 Summary How to predict stock fluctuations of common squid? (Especially, decline of winter stock during a cool year and regime) Strong northwest wind (fall-winter) Expansion of cold water area Feeding migration to Yellow Sea and Bohai Sea Shift of spawning migration route Segregation of spawning area between fall & winter Decrease of juvenile squid (springearly summer) and winter cohort catch (after October) Increase of mackerels? Southern shift of spawning area (winter)

43 Thanks from the squid!