Stock reduction analysis of blue shark (Prionace glauca) caught in the Indian ocean

In this paper a Stock Reduction Analysis (SRA) based on catch data and on prior information concerning the intrinsic growth rate (r) was used to estimate maximum sustainable yield of blue shark (Prionace glauca) caught in the Indian Ocean. The uncertain concerning catch is high. Five different catch time series were considered. All the results indicate that the stock was not overfished in 2015 which is the end of the time series. However, catches have increased fast after 1990 and were higher than maximum sustainable yield (MSY) after mid of 2000’s. Probably the biomass (B) was still BMSY in 2015, but the ratio B/BMSY will be below one in a near future if the catches and the fishing mortality continue to increase. The probability of overfishing blue shark is close to or higher than 0.6 in the near future even if the catches remain close to the average of catches of recent years.