A study on spatial-temporal distribution and marine environmental elements of Symplectoteuthis oualaniensis fishing grounds in outer sea of Arabian Sea

In order to understand the development status of fishery resources in the waters off the Arabian Sea in the high seas of the northwest Indian Ocean, and to explore the fishery distribution of Symplectoteuthis oualaniensis and the impact of fishery environmental factors on its resources, we carried out two surveys in the waters off the Arabian Sea, obtained the data of catch and operating water temperature at each survey site, and used the Generalized Additive Model (GAM) to analyze the impact of various marine environment and tempo-spatial factors on the catch per unit effort (CPUE) of S. oualaniensis in that sea area. The results show that: 1) There are mainly three areas with high CPUE values (60°E−61°E, 16°N; 62°E, 16°E−18°N; 61.50°E−63°E, 17°N−17.75°N). 2) The influencing factors of the best GAM model included latitude and longitude, lunar calendar day, sea surface temperature (SST), chlorophyll a concentration (Chl a) and sea surface temperature anomaly (SSTA). The top three explanatory factors with the highest explained variance were longitude and latitude, lunar calendar day and SSTA. 3) The total number of catch on the no-moonlight night was 1.38 times the number of catch on the bright moonlight night, and the total catch of the no-moonlight night was 108.21% higher than the total catch of the bright moonlight night. 4) According to the GAM model, the optimal SST range was 26.5−27.5°C; the Chl a concentration range was 0.30−0.50 mg·m⁻³; the SSTA range was 0−0.4°C.