The effects of variables on the success of Thunnus thynnus fishing in the Eastern Mediterranean Sea

摘要

This research focuses on the relationships between fishing success and various influential factors by using a statistical model based on observed data. The potential factors that significantly impact fishing success results were determined using in situ dataset collected with geographic coordinates in 126 fishing operations by three purse seines. A generalized additive model (GAM) for catch variables of Atlantic bluefin tuna Thunnus thynnus (presence-absence) was used to analyse fishing success under different variables: fishing operation (shooting duration, closing the racing duration, setting speed, sinking speed), gear design (length-height ratio), geophysical coordinates (latitude and longitude) and environmental conditions (sea surface temperature, depth, current speed at 10 m). The best fit model results showed that sea surface temperature makes a major contribution to the successful fishing of T. thynnus, as evidenced in previous work. In addition, some other factors (depth, shooting duration, closing the lacing duration, current speed at 10 m, setting speed, sinking speed, and length-height ratio) also affect the success of T. thynnus fishing in the Eastern Mediterranean Sea. These results help to indicate several fishing strategies that will be adopted to encourage fishers to increase their efforts.