Potential Effect of the Intrusion of the Kuroshio Current into the South China Sea on Catches of Japanese Eel (Anguilla Japonica) in the South China Sea and Taiwan Strait

Yang-Chi Lan,Zhen Lu,Ching-Hsien Ho,Long-Jing Wu,Bo-Yi Lu

doi:10.3390/jmse9121465

Yang-Chi Lan, Zhen Lu + Show 3 more

Open Access

https://doi.org/10.3390/jmse9121465

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Abstract

This study examined the effect of the intrusion of the Kuroshio Current (KC) into the South China Sea (SCS) and the Taiwan Strait (TS) (SCS–TS region) on changes in catches of larval A. japonica in the traditional fishing ground waters of Gaoping near southwestern Taiwan in the SCS–TS region. First, the oceanic environment and recruitment trends from 1967 to 2019 were investigated based on secondary data. Then, field surveys were conducted to obtain primary data regarding the intrusion of the KC into the SCS, as well as the changes in the fishing sites and catches of A. japonica in the fall and winter of 2014–2015. Hence, the association between oceanic conditions and the number of A. japonica migrating into the SCS–TS region was explored. From 1967 to 2019, the recruitment proportion in the fishing grounds that formed due to the Kuroshio Branch Current (PKSBC) fluctuated significantly. Overall, positive values were observed for the Oceanic Niño Index for each year with a PKSBC > 50%, corresponding to El Niño conditions. In each year with a PKSBC > 70%, a looping path and a warm–core eddy appeared.

Highlights

The Japanese eel Anguilla japonica is an important eel species for the marine fishery and aquaculture industries in East Asian countries and is currently the only eel species whose farming still relies on wild–caught larvae
In terms of remote sensing data, the monthly SST data were sourced from the moderate resolution imaging spectroradiometer (MODIS) onboard the Aqua satellite launched by the National Aeronautics and Space Administration (NASA) for the region located at
After dividing the A. japonica catch into PKC and PKSBC based on the fishing ground formation mechanism, we found that the catch proportion changed every year, and there was a phenomenon of regime change between PKC and PKSBC

Summary

Introduction

The Japanese eel Anguilla japonica is an important eel species for the marine fishery and aquaculture industries in East Asian countries and is currently the only eel species whose farming still relies on wild–caught larvae. Intensifying climate change and accelerating decline in larval eel stocks may further increase the high volatility and uncertainty in catches of A. japonica from the fishing ground waters of Taiwan, which is where they migrate (including the Upstream Kuroshio and the South China sea (SCS)—Taiwan Strait (TS) region). These conditions may accelerate the decline in catches in the SCS–TS region, which is where the Kuroshio. We attempted to assist in solving the problem of in situ data from the SCS–TS region and hope that the results of this study can be used as a reference for other researchers

Research Methods

Climate Index Data (ONI and PDO)

Fishing Data

Satellite Data

ONI and PDO

Environmental Data

Spatial Statistics

Changes in the Catch Ratio between KC and KSBC

CFV–Borne Field Observations of Fishing Surveys

Correlation between KBSC Catches and Regional SST, PDO, and ONI

Changes inin thethe

Changes in the Recruitment Proportions of Larval Eels in the Waters through Which the Main