Fishing, sizes and sex-ratios of blue shark and silky shark caught by Indonesian tuna longline in the eastern Indian ocean
The production of shark captures in Indonesia is derived from multiple forms of fisheries, where these fisheries make shark resources the primary catch (target species) on artisanal fisheries and economically valuable by catch on fishing tuna industries. Silky sharks (Carcharhinus falciformis) and blue sharks (Prionace glauca) are the predominant shark species caught in artisanal and tuna fishing industries respectively. Datasets included information on catch location and CPUE, and specimen size and sex. a total of 3,181 shot-by-shot catch and effort data were acquired from the Indonesian scientific observer activity. The main fishing grounds cover the western and southern part of Indonesian waters, extending from 75o E to 35o S, with greatest CPUE tending to occur at latitudes 90o-100o E to 30o-35o S while silky shark very rare caught and more to occur near to neritic zone. A total of 1,756 blue shark and 99 silky shark records collected between 2006 and 2021 were compiled, with the sizes ranging from 50 to 312 cmFL and 29 to 200 cmFL (fork length) with differences in the sex ratios by quarter were also detected.