Landmark for the spawning of Japanese eel

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Beverly Cameron
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1 Landmark for the spawning of Japanese eel Shingo KIMURA and Katsumi TSUKAMOTO Ocean Research Institute, Univ. of Tokyo Salinity front in the North Equatorial Current El Niño/Southern Oscillation Index Difference of water property (Particulate Organic Matter) Environmental factors spawning behaviors larval transport 2002 (El Niño) &2004 (La Niña trend) Hakuho-maru research cruises

2 Korea Japan 30 N Adult migration Trade 20 Nwind 10 N Taiwan Kuroshio Northward larval Ekman transport.. Spawning ground Mindanao Current Low-salinity region North Equatorial Current Salinity front 120 E 140 E 160 E Water circulation and distribution of water masses

3 North Equatorial Countercurrent average North Equatorial Current S.D. Temp. Salinity 27 year averaged temperature and salinity sections Mean and standard deviation

4 Salinity front Salinity front Location of the salinity front depending on ENSO

Usual years Strong current velocity south of the salinity front Good condition for appropriate larval transport Difference of water mass property Landmark for detection of the spawning ground El Niño

5 Usual years Strong current velocity south of the salinity front Good condition for appropriate larval transport Difference of water mass property Landmark for detection of the spawning ground El Niño years Southward movement of the salinity front Bad condition for the larval transport Decrease of the glass eel catch in Japan Glass eel catch in Japan and SOI Next task Confirmation of this phenomenon during El Niño Detection of factor of water property

0 100 200 300 400 500 Salinity front May 2002 34.0 34.2 34.4 34.6 34.8 34.8 34.6 34.4 35.

2 34.4 34.6 34.8 35.0 34.8 34.6 34.4 7 9 11 13 15 17 latitude ( N) 34.2 34.4 34.6 34.8 35.0 35.

6 Salinity front May latitude ( N) El Niño just started Salinity front July latitude ( N) psu Difference of location of salinity before and during El Niño

7 latitude (N) 30 mm 20 mm 10 mm Salinity front 2 indivs. 5 indivs. 10 indivs. longitude (E) Southward movement of the salinity front and leptocephali distribution associated with El Niño Salinity section and leptocephali distribution in research cruise

0 100 Rapid transport with northward shift by wind depth (m) 200 300 400 8 10 12 24 22 18 20 16 14 500 7 9 11 13 15 17 latitude (N)

8 0 100 Rapid transport with northward shift by wind depth (m) latitude (N) Tracks of Argos buoys geostrophic velocity (m/s) Current velocity Water circulation in the North Equatorial Current

9 (El Niño) δ 13 C( ) leptocephalus 0m 50m -24 Salinity front Latitude ( N) Carbon stable isotope ratio of leptocephali and POM

10 (La Niña trend) δ 13 C( ) leptocephalus 0m 50m Latitude ( N) Carbon stable isotope ratio of leptocephali and POM

11 (El Niño) 7 30 δ 15 N( ) length (cm) δ 13 C( ) δ 13 C-δ 15 N map of the Japanese eel leptocephali

12 (La Niña trend) δ 15 N( ) length (cm) δ 13 C( ) δ 13 C-δ 15 N map of the Japanese eel leptocephali

100 particles from the spawning ground Entrainment

13 Delay of arrival in Korean coasts Winddriven transport to west coast of Taiwan Trajectories of 100 particles from the spawning ground Entrainment into gyre Results of numerical simulation of larval transport

14 20 N 120 E 131 E 137 E Kuroshio Salinity front 10 N 16 N 16 N Mindanao Current 50m Northward transport by the trade wind Ekman layer Vertical migration Larval transport NEC Adult migration Spawning migration of the Japanese eel

15 Korea Japan 30 N Migration 20 N Taiwan Kuroshio NEC.. 10 N Mindanao Current Spawning ground Salinity front 120 E 140 E 160 E Latitude difference of bifurcation and salinity front

16 Correspondence to climatic regime shift Catch of glass eel (t) Loire in France Total catch in Japan culture including import Tanegashima Kagoshima Catch of glass eel (Kg) Glass eel catch in Japan and Europe

17 North Atlantic Oscillation Index European eel case: unclear temperature gradient causes losing detection of hot spot Southern Oscillation Index Coincidence of large change Fluctuations of NAO index and SOI in last 130 years

18 Conclusion Hot spot for the Japanese eel is located in the NEC and related to salinity front Large southward displacement of salinity front associated with El Niño Narrow highway between 10 N and 15 N for appropriate larval transport Distribution of smaller leptocephali in south of the salinity front which moved southward associated with 2002 El Niño Difference of water mass south and north of salinity front is related to POM difference High possibility that leptocephali ingest food south of the salinity front Surface water property in the NEC is significantly different between El Niño year and La Niña year Decrease of European eel may be explained same as the Pacific case

Review of Ocean-Atmospheric Factors in the Atlantic and Pacific Oceans Influencing Spawning and Recruitment of Anguillid Eels

American Fisheries Society Symposium 69:231 249, 2009 2009 by the American Fisheries Society Review of Ocean-Atmospheric Factors in the Atlantic and Pacific Oceans Influencing Spawning and Recruitment