MEPS 623:25-37 (2019)  -  DOI: https://doi.org/10.3354/meps13026

ABSTRACT: The purpleback flying squid Sthenoteuthis oualaniensis is an important ecological and fishery species in the South China Sea (SCS). This study investigated environmental effects on the spatiotemporal variability of S. oualaniensis in Xisha-Zhongsha waters, SCS, using generalized additive models (GAMs); results showed that 43.06% of the total variation in S. oualaniensis catch per unit effort (CPUE) was explained by these factors. Based on the stepwise GAMs, the most important factor was sea surface temperature (SST), with a contribution of 14.80%, followed by longitude, month, chlorophyll a (chl a) concentration, and latitude, with contributions of 8.8, 5.94, 5.90, and 3.09%, respectively. Year and sea surface height anomaly (SSHA) each had a slight influence on the model, explaining approximately 2.97 and 2.10% of the variation in S. oualaniensis CPUE, respectively. S. oualaniensis was mainly distributed between 14-18°N and 110-115°E, where SSTs were 27-28.5°C, chl a concentrations were 0.11-0.15 mg m^-3, and at the periphery of eddies where the SSHA was close to 0 m. Analysis of the center of gravity for S. oualaniensis showed that the population shifted southwards by 2° latitude in the spring of 2008, during La Niña conditions. The findings of this study can help to better the understanding of the movement of S. oualaniensis in Xisha-Zhongsha waters and promote better fishery management under a changing climate.

KEY WORDS: Sthenoteuthis oualaniensis · Environmental effects · Spatiotemporal variability · Generalized additive models · Xisha-Zhongsha waters