Investigating ENSO effects on the spawning migration of Japanese anchovy in the East China Sea using a behavior-hydrodynamic model
Date Issued
2015
Date
2015
Author(s)
Yang, Chieh-Hsu
Abstract
Mature individuals of Japanese anchovy (Engraulis japonicus) migrate from the East China Sea to the coastal water of northern Taiwan to spawn during winter. The anchovy larvae then form an important fishery resource for Taiwan. Previous studies indicate that the interannual variation of anchovy larvae catch per unit effort data exhibited a negative correlation with ENSO; however, the detail underlying mechanism explaining how ENSO affects ocean currents or environmental conditions, which in turn determine the fluctuations of anchovy larvae, remains unclear. To bridge the knowledge gap, we construct historical circulation patterns in the East China Sea and the Taiwan Strait by hydrodynamic models, and use individual-based model to represent fish behavior for simulating the migration process of Japanese anchovy. Comparing model results under various ENSO states (strong El Niño (La Niña) and moderate El Niño (La Niña) states), we find that the fluxes of Japanese anchovy populations toward Taiwan is positively correlated with the strength of China Coastal Current, which is driven by the East Asian Winter Monsoon. Specifically, in El Niño (La Niña) states, the East Asian Winter Monsoon decreases (increases) in boreal winter and weakens (strengthens) the China Coastal Current and in turn decreases (increases) the fluxes of Japanese anchovy populations migrating toward the coastal water of Taiwan. The connection between the ENSO, East Asian Winter Monsoon, China Coastal Current, and spawning migration of Japanese anchovy suggests that large-scale environmental changes may affect reproductive biology of species through meso-scale physical environmental factors. The results also indicate that the dynamics of migration processes should be considered in fishery managements.
Subjects
ENSO
East Asian Winter Monsoon
China Coastal Current
Japanese anchovy
migration process
fish behavior-hydrodynamic model
hydrodynamic model
individual-based model
SDGs
Type
thesis
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