Abundance Variability and Environmental Drivers of Commercial Fish in the Northern South China Sea across ENSO Phases under Climate Change Scenarios

Abstract

The El Niño-Southern Oscillation (ENSO) is a dominant driver of environmental variability in the Northern South China Sea (NSCS). Under climate change, understanding how these oscillations impact commercial fisheries is crucial for adaptive management. This study statistically quantifies the response of 21 commercial fish species in the Taiwan Bank upwelling region to ENSO phases under future warming scenarios (1951-2100). We forced the Dynamic Bioclimatic Envelope Model (DBEM) with environmental data derived from the ensemble mean of the GFDL ESM2M Earth System Model to isolate robust climate signals. Using Analysis of Variance (ANOVA) and univariate linear regression, we examined biomass variability across El Niño, La Niña, and Neutral phases. The results reveal that species abundance is significantly higher during La Niña events compared to El Niño and Neutral phases (p-value < 0.05). Univariate regression analyses identified Sea Surface Temperature (SST) and Net Primary Production (NPP) as the primary drivers, showing significant negative and positive correlations with biomass, respectively. These findings provide statistical evidence that La Niña-induced upwelling-characterized by cooler waters and enhanced productivity-creates a favorable “buffer” period for fishery resources. We suggest that fisheries management strategies should explicitly account for these ENSO-driven phase differences to mitigate risks during less favorable El Niño periods.