Monthly spatio-temporal distribution of potential habitat of jumbo flying squid Dosidicus gigas in the Equator and its relationship with environmental factors

In order to explore the relationship between spatial and temporal distribution of potential habitats of marine economic species and environmental conditions and effectively help enterprises to utilize and develop fishing grounds. Dosidicus gigas is widely distributed in the Eastern Pacific Ocean, from California (30°N) to Chile (45°S), and can reach 125°W in Equator. Based on the fisheries data of Chinese squid-jigging fishing vessels in equatorial waters from 2012 to 2018, and environmental data including sea surface temperature (SST), sea surface salinity (SSS), chlorophyll-a (Chl-a), net primary production (NPP), photosynthetically active radiation (PAR), eddy kinetic energy (EKE) and sea level anomaly (SLA), this study established the maximum entropy model (MaxEnt) to analyze the spatial and temporal variations of habitat and the influence of environmental factors from month to month. The results showed that CPUE was higher from January to March, while the fishing effort was higher from July to August. AUC of the MaxEnt model were more than 0.8 in each month, indicating that the simulation results were accurate. The spatial and temporal distribution characteristics of suitable habitat were significant in different months. The suitable habitat of D. gigas was distributed between 3°N-3°S, and gradually moved eastward from January to May. Suitable habitat began to shift to the southeast (85°-102°W, 2°-5°S) in June and moved northwestward in August. The results of contribution rate for environmental factors showed that impacts of environmental variables on habitat distribution of D. gigas in different months were significantly different. The cumulative contribution rate of key environmental factors to the model was more than 60% in each month. Overall, SST, NPP, PAR and EKE were the key environmental factors that strongly affected the habitat distribution of D. gigas. Suitable range of each key environmental factor showed significantly monthly variations. In addition, it was speculated that the distribution of suitable habitat of D. gigas was extremely sensitive to SST patterns, and currents and eddies might have a great impact on the distribution of D. gigas. The results showed that there were obvious monthly distribution characteristics in the D. gigas habitat in the equatorial waters, and the effects of environmental factors on the habitat distribution were significantly different.