Response of the spatiotemporal distribution of crimson seabream (Paerargyrops edita) to La Niña event in the northern Beibu Gulf, South China Sea

Abstract

Based on fishery resources and environmental data collected during six cruises conducted in the spring and autumn from 2021 to 2023 in the northern Beibu Gulf, South China Sea, we conducted an analysis on spatiotemporal distribution of crimson seabream (Paerargyrops edita). We employed a gradient forest analysis (GFA) and generalized additive model (GAM) to investigate the relationship between their distribution and six environmental factors, including sea surface temperature (SST), sea surface salinity (SSS), sea surface chlorophyll a concentration (Chla), bathymetry (Depth), sea surface height (SSH), as well as the Niño 3.4 index (NI). The results revealed distinct spatiotemporal variations in the distribution of crimson seabream in the northern Beibu Gulf, with an average stock density of 114.21 kg/km2. During spring, there was a significantly higher abundance at 160.46 kg/km2 compared to the autumn value of 67.95 kg/km2. In the first analysis, based on 1000 runs of the GFA, it was observed that the selected explanatory variables demonstrated excellent predictive capabilities for variations in stock density. Specifically, the SST, SSS, and NI were found to have a high importance, indicating a significant influence of climate and environmental factors such as the El Niño-Southern Oscillation (ENSO) and SST on the crimson seabream abundance. Subsequently, we constructed a GAM to further investigate the impact of environmental factors on the distribution patterns of crimson seabream. The GAM also confirmed a strong correlation between the selected environmental factors and crimson seabream abundance. The main distribution of crimson seabream abundance exhibited a significant negative correlation with the SST, which fell within the range of 24–28 °C. The stock density of crimson seabream slightly increased at SSS levels ranging from 32.5 PSU to 33.5 PSU, indicating a correlation between the two factors. The crimson seabream was distributed across a Chla range of 0–4 mg/m3, with a gradual increase in stock density as the Chla levels increased. Stock density was positively correlated with SSH, but was negatively correlated with NI. In this study, we examined the distribution of crimson seabream and its main influencing factors by incorporating various environmental factors and a network analysis under different climate events. This research provides theoretical support for investigating the mechanisms of fishery stock in response to climate change. It also contributes to the existing body of knowledge on changes in fish resources in Beibu Gulf during abnormal climate events.

Keywords

• Northern Beibu Gulf
• Crimson seabream
• Gradient forest analysis
• Generalized additive model
• La Niña event