Association between Skipjack (Katsuwonus pelamis) distribution caught by Iranian purse seiners and environmental variables in the Indian Ocean

Association between environmental variables and target species is the most important point in aquatic ecology. This study considered the possible relationship of spatial, temporal and some satellite derived environmental variables on skipjack tuna (Katsuwonus pelamis) distribution to finally help implementing of ecosystem based fisheries management for stock recovery program and management of skipjack tuna. Results of generalized additive model (GAM) (by assuming two distributions; binomial and Gaussian) revealed temporal and spatial explanatory variables plus net primary production (NPP), sea surface temperature (SST), sea surface salinity (SSS), mixed layer depth (MLD) and ocean current indices have greatest impact on skipjack tuna distribution in both cold and warm season. Comparing of two different model showed, binomial distribution had higher ability in final model deviance explanation and its value in warm season was higher than cold season. In addition, habitat suitability study showed suitability of some parameters in cold and warm season were different, then it must be noticed in future studies. Since the first step in implementing ecosystem based fisheries management is the sufficient knowledge on ecosystem and distribution of target species in relationship to environmental variables, therefore this study could help Iranian purse seiners to improve their catch efficiency in order to help to implementing of ecosystem based management for skipjack tuna and future fisheries management in the Indian Ocean and Oman Sea.