The distribution and fluctuations in abundance of small pelagic species such as anchovy are largely affected by climate change. We hypothesized that the future projected rise in temperature will result to a northward shift of Japanese anchovy (Engraulis japonicus) habitat and a subsequent increase in relative abundance. To test this hypothesis, we explored the link between Japanese anchovy abundance and environmental conditions using machine-learning and statistical models. The models were fitted with catch per unit effort (CPUE) as the response variable and remotely sensed data of sea surface temperature (SST), sea surface chlorophyll-a (Chl-a), assimilated information of sea surface salinity (SSS), meridional and zonal ocean currents, and depth as environmental covariates. Our results showed that the abundance of E. japonicus was significantly influenced by environmental factors. In particular, salinity front and SST highlight strong relationships with winter CPUE distribution. Based on these models, the results reinforced our hypothesis and showed that the warming ocean will drive a substantial shift in Japanese anchovy habitat in the China seas. SST and CPUE showed negative correlations with the El Niño Southern Oscillation (ENSO) index. These findings underpin ramifications of the climate-driven habitat shift of small pelagic fish species on the regional marine ecosystem in the China seas.

The Yellow Sea is the southern limit of the distribution of Pacific cod (Gadus microcephalus), and the Yellow Sea Cold Water Mass (YSCWM) provides an appropriate over‐summering habitat for this species. Tidal current is the major component of the Yellow Sea hydrodynamic system, and its periodic variations influence the local ecological conditions and related ecosystems, particularly in the YSCWM, which is stratified in summer. To investigate the influence of tidal currents on Pacific cod growth, otolith daily increment in young‐of‐the‐year (YOY) Pacific cod in the Yellow Sea was analyzed in 2017. These data were integrated with a simulated tidal current using a multi‐scenario time‐delay analysis. This showed that: (1) the otolith daily increment exhibited a strong signal similar to the fortnightly tidal variation; (2) there was a lag of ∼8 days between the highest growth rate induced by the tidal current variation and monthly spring tide; and (3) the influence of the tidal current on otolith daily growth was stronger after migration of the cod into the YSCWM, particularly during the settlement stage. Given the stratified ocean structure during the over‐summering period, enhanced tidal mixing during the fortnightly spring tide would improve the exchange of nutrients and oxygen within the YSCWM, and lead to a delayed response of otolith growth due to feeding/digestion and subsequent growth. Therefore, variations in the tidal current have a marked positive ecological effect on the growth of YOY Pacific cod, and ultimately on the YSCWM ecosystem.

The waters around Taiwan are impacted by the Kuroshio and coastal currents, resulting in a high productivity and a high diversity of marine life. As a consequence, there are a multitude of fisheries around Taiwan, conducted by a fleet that has grown enormously in the last four decades. Here, we investigate the effect of the resulting fishing pressure on 16 commercial fish stocks including demersal and pelagic species in the coastal and offshore waters of Taiwan using the Monte Carlo Catch-Maximum Sustainable Yield (CMSY) and Bayesian Schaefer Model (BSM) methods. Both of these methods required principally catch time series, with the BSM methods also requiring catch-per-unit-of-effort data. The results show that of the 16 assessed stocks, 10 stocks have collapsed, 2 are severely overfished, 2 are overfished, 1 is slightly overfished, and only 1 stock remains in a healthy status; these troubling results are attributed to excessive fishing pressure. However, climate-driven environmental variability may be another factor affecting the fishery resources around Taiwan, as evidenced by chub mackerel Scomber japonicus, the one stock deemed healthy, which is here attributed to favorable environmental condition. Using the fisheries reference points provided here, rebuilding plans could be provided for the other 15 species; however, such plans are not likely to be successful without reducing the size of the Taiwanese fishing fleet.