Abstract:Marine environmental factors affect the survival, growth, and reproduction of fish, etc., which play an important role in controlling fish population distribution. In addition, variation of marine environmental factors influences the spatial distribution and aggregation of fish. Based on remote sensing (RS) technology and geographic information system (GIS), the relationship between the spatial distribution of wintering anchovy (Engraulis japonicas) and environmental factors are analyzed, and then generalized additive models (GAMs) were established to quantitatively investigate the effects of spatio-temporal and environmental factors on stock density, using data collected by bottom trawl surveys and RS in central and southern Yellow Sea during 2000~2015. The results showed that wintering anchovy was concentrated in certain ranges of sea surface temperature (SST), chlorophyll a (Chl-a) concentration, as well as temperature gradient (TGR). The final model accounted for 44.76% of the variance in anchovy stock density. The spatio-temporal factors (year, hour, longitude, latitude) all had significant effects (P<0.05) on stock density, and spatial factors had the greatest impacts, accounting for 35.4% of the variance. Environmental factors such as water depth, SST, and TGR all had significant impacts on stock density (P<0.05). However, Chl-a concentration did not have a significant effect on anchovy stock density. The distribution of Chl-a concentration represents certain hydrodynamic characteristics; therefore, Chl-a concentration was included in the final model. Wintering anchovy was most abundant where the SST was between 7℃ and 11℃. The effect of SST on stock density was positive for temperatures lower than 9.5℃, and then there was a negative effect at warmer temperatures. Stock density was high where Chl-a concentration was between 1.2 and 2.3 mg/m3 and where TGR was from about 0.7℃ to 2.5℃; however, there were slight changes between the abundant ranges. The results of this study have important implications for fisheries management under marine environment dynamic scenarios in the Yellow Sea.
