Spatiotemporal distribution of Decapterus maruadsi in spring and autumn in response to environmental variation in the northern South China Sea

Abstract

Understanding relationships between the spatiotemporal variability of fishery resources and marine environmental variables forms the basis of effective development and utilization of the northern South China Sea (NSCS) fishery resources. Decapterus maruadsi is one important pelagic economic fish which inhabits the coastal warm waters of the NSCS. We examine the spatiotemporal distribution and central of gravity (CoG) of D. maruadsi in the NSCS in spring and autumn from 2015 to 2017 with generalized additive models (GAMs), using fishing trawl data, and remote sensed sea surface temperature (SST), sea surface salinity (SSS), sea surface wind (SSW), chlorophyll a concentration (Chl-a), and the sea level anomaly (SLA) data. During spring D. maruadsi occurs mainly in a small area from 110.5–111 °E and 18.25–19.25 °N, at about 72 m, SST 24.4–26.8 °C, SSS 32.9–34.0 PSU, and SLA -0.04 to 0.04 m. During autumn these ranges shift to 112.25–114 °E and 20.25–21.25 °N, 62 m, 28.5–28.8 °C, and 33.4–34.1 PSU, respectively (D. maruadsi was insensitive to SLA during autumn). Accordingly, we deem the most important variables affecting the distribution of this species to be water depth and SSS in spring and SSS in autumn. CPUE of D. maruadsi was high in autumn and low in spring, with the CoG shifting from spring to autumn northwards by 0.4 °N and eastwards by 0.7 °E. This shift is likely influenced by this species’ life habits. Higher D. maruadsi CPUE in 2016 could partly be associated with La Nina and Typhoon climate anomalies. Our results provide a basis for scientific assessment and effective conservation of NSCS fishery resources.