This study systematically analyzes the species composition， abundance， and spatial distribution of bycatch in purse seine fisheries using tuna fishery and bycatch data provided by the Western and Central Pacific Fisheries Commission （WCPFC） from 2013 to 2022. Additionally， the correlation between bycatch rates and the catch rates of three major target species：skipjack tuna （Katsuwonus pelamis）， yellowfin tuna （Thunnus albacares）， and bigeye tuna （Thunnus obesus） was examined to identify distinct bycatch patterns and their relationship with target species composition.The results indicate that 48 bycatch species were recorded， totaling 439 623 individuals， primarily comprising cetaceans， sharks， and sea turtles. Among these， the silky shark （Carcharhinus falciformis） was the most frequently bycaught species， with 418 387 individuals， accounting for 95% of the total bycatch. Bycatch was predominantly concentrated in waters between 10°S-10°N latitude and 140° E-150° W longitude. Furthermore， bycatch rates were generally higher in eastern longitudes than in western longitudes， with cetacean bycatch exhibiting the most pronounced east-west variation.Correlation analysis revealed no significant relationship between the bycatch rates of cetaceans and sharks and the catch rates of target tuna species. However， the bycatch rate of sea turtles showed a positive correlation with the catch rates of skipjack and bigeye tuna. These findings highlight the high bycatch risk associated with purse seine fisheries， particularly for silky sharks， which dominate the bycatch composition. The overall higher bycatch rates in eastern longitudes further underscore the need for region-specific mitigation strategies.This study provides valuable scientific insights to support bycatch reduction measures， contributing to the conservation and sustainable management of marine ecosystems.