Variation in the catch rate and distribution of three important commercial Spanish mackerel (Commerson: Niphonius: Guttatus) related to ENSO events around the waters off Taiwan

Abstract

Spanish mackerel species are migratory species, also are highly commercially valuable in Taiwan. However, in recent years, climate change and variability have influenced oceanographic conditions, substantially impacting the population dynamics of pelagic species. This study developed weighted habitat suitability index models for three crucial Scomberomorus species-Scomberomorus commerson, Scomberomorus niphonius, and Scomberomorus guttatus-in the waters off Taiwan. Remote sensing data including sea surface temperature, sea surface chlorophyll-a, sea surface salinity, and sea surface height, along with voyage data records that included detailed catch data from Taiwanese drift gillnet fisheries were collected during 2011-2019. The primary fishing grounds for S. commerson are located in the central to southwestern Taiwan Strait, while S. niphonius and S. guttatus are mainly found in the coastal waters off western Taiwan. In autumn, the oceanographic factor preferences are relatively similar among Scomberomorus species, with sea surface temperature being the primary influencing factor. Sea surface height turns to the main influencing factor in winter. Based on the results of the weighted habitat suitability model, we found seasonal differences in habitat preferences and ranges. There is more pronounced overlap in potential habitat in autumn and partial separate condition in potential habitat in winter among Scomberomorus species. Further exploration of the spatiotemporal distribution dynamics of Scomberomorus species under different ENSO periods revealed that during La Nina periods, the potential habitat ranges are broader and extend further south. In contrast, during El Nino periods, and the potential habitat ranges contract northward. Habitat suitable index model may be a useful approach for evaluating possible changes in habitat suitability resulting from climate change or other oceanographic phenomena and in offering suggestions for fishery scientific management.