Influence of environmental factors on CPUE of three different fishing methods in skipjack tuna fisheries

Skipjack tuna (Katsuwonus pelamis) is widely distributed in tropical and subtropical waters around the world and is a key target species in global tuna fishery. The abundance of its resources is influenced by various marine environmental factors. In order to explore the mechanisms by which precipitation affects the distribution and variation of resources in different K. pelamis stocks, based on the data from the pair trawl fishery in Mauritanian waters during 2017−2019, data from the purse seine fishery from the Western and Central Pacific Ocean during 2018−2020, and data from the longline fishery recorded on the IATTC website during 2010−2020, combining with environmental data such as precipitation, sea surface salinity (SSS) and sea surface temperature (SST), we analyzed the spatiotemporal distribution of catch per unit effort (CPUE) for three different fishing methods of skipjack tuna and its relationship with environmental factors such as precipitation by Generalized Additive Model (GAM). The findings indicate that month significantly influenced the CPUE of skipjack tuna for pair trawl and longline fishing methods (P<0.05). Latitude also had a significant effect on all the three fishing methods (P<0.05). Precipitation exhibited an extremely significant effect (P<0.001) on the CPUE of skipjack tuna for pair trawl fishing method and a significant effect (P<0.05) for purse seine fishing method. The trend of this effect was relatively consistent, with higher CPUE occurring within a more suitable range of precipitation. However, the effect of precipitation on the CPUE of skipjack tuna for longline fishing method was not significant. Sea surface salinity and sea surface temperature also had significant effects on the CPUE of skipjack tuna for all the three fishing methods (P<0.05). Hence, when analyzing the effects of environmental factors on fishery CPUE in the future, it is recommended to include precipitation in conventional marine environmental factors.