Climate change impacts on growth and migration of Japanese anchovy (Engraulis japonicus) in the East China Sea and its uncertainties.

Japanese anchovy (Engraulis japonicus) is an important species not only as an exploited species but also as prey for variety of predators. However, the biomass of Japanese anchovy has shown large fluctuation and is one of the main actors of the fish species alternation responding to basin scale climate variabilities. Therefore, it is a key question how anchovy respond to climate change in future. We developed a fish-migration and growth model using environmental conditions derived from simulations of a coupled ocean circulation and ecosystem model. For the ocean circulation model, a high resolution (1/10 deg.) FRA-ROMS (Fisheries Research Agency - Regional Ocean Modeling System) was used. For the marine ecosystem model, eNEMURO (an extended version of North Pacific Ecosystem Model for Understanding Regional Oceanography) was used. For contemporary and future climate forcing, the output of MRI-CGCM3 with three scenarios (RCP2.6, RCP6.0 and RCP8.5) were averaged during 2011-2020, 2051-2060 and 2091-2100, then the FRA-ROMS-eNEMURO was integrated with those climatological forcing for 26 years and the simulated results in the last year were used to integrateFRA-ROMS-eNEMURO.FISH. The initial spawning grounds were estimated based on the sea surface temperature (SST) and day length with limitation of ocean depth less than 1000 m. The spawning grounds shifted to northward under warming conditions however because of day length limitation, the available eggs decreased by the northward shift. The larvae transported to southern part of Kyushu Island in Japan (current main fisheries ground for anchovy larvae) were projected to decrease under warming conditions and the peak timing of larvae supply was shifted earlier. The projected results indicate severe conditions of local fisheries in the southern part of Kyushu Island.

However, three sub-populations are defined in Japan: Pacific stock, East China Sea stock, and Seto-inland Sea stock and difference was found in weights-at-age and longevity. Therefore, we re-estimated swimming performance of the three anchovy stocks based on laboratory experiments. The sensitivity analyses of swimming efficiency will be conducted respect to the migration route of anchovy base on the estimation.