Abstract
Spawning ground of Japanese eel (Anguilla japonica) is located near the West Mariana Ridge seamount. The species travels through the North Equatorial Current (NEC) and then enters the Kuroshio Current (KC) on the migration toward East Asian growth habitats. Therefore, El Niño–Southern Oscillation (ENSO) events serve as the potentially important drivers of interannual variability across the equatorial Pacific. Because the NEC bifurcation and salinity profiles are related to ENSO events, we investigated the influence of locations of the NEC bifurcation and salinity front on the success of larval entry to the KC by numerically modeling particle transport in ocean currents from 1972 to 2013 and possible effects on the size of glass eels at continental recruitment and, via otolithometry on the duration of larval migration. Circulation and hydrography used for particle tracking were obtained from the results of the Model for Interdisciplinary Research on Climate (MIROC) high-resolution forecasting experiment. Our results demonstrated that during El Niño years, (1) the southward movement of the salinity front might cause the larvae to experience slower currents and (2) the northward movement of the NEC bifurcation might broaden the separation between their spawning ground and NEC bifurcation, thus prolonging the time needed for the larvae to enter the KC from their spawning ground, because of which the duration of entrainment in the water column and body size increase when eels reach estuarine waters. In addition, this might cause more water to flow into the Mindanao Current (MC), leading to a decline in the rate at which larvae get entrained into the KC.
Highlights
The Japanese eel, Anguilla japonica (Temminck & Schlegel), is mainly distributed in Taiwan, China, Korea, and Japan [1,2,3]
The A. japonica specimens used to measure the larval duration (LD) and total length (TL) in this study were collected from the estuaries of Taiwan over a 9-year period (Table 1)
The results revealed that the relationship between mean TL and mean LD showed statistically positive correlation (r = 0.40, p < 0.05) (Fig 3)
Summary
The Japanese eel, Anguilla japonica (Temminck & Schlegel), is mainly distributed in Taiwan, China, Korea, and Japan [1,2,3]. It is a commercially important freshwater fish in East Asia. Eel was discovered near 14 ̊-17 ̊ N, 142 ̊-143 ̊ E in the North Equatorial Current (NEC) to the west of the Mariana Islands, approximately 3000 km away from their growth habitats in East Asia (Fig 1) [4, 5]. Leptocephali are transported by currents, which are mainly 50–150m deep [8], and they metamorphose into glass eels as they approach continental growth habitats. Glass eels show a benthic–sheltering behavior [1, 6, 8] and actively swim toward nearby estuaries and rivers for further growth [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
