Standardized catch rates of blue sharks in the western North Atlantic Ocean from the U.S. pelagic longline observer program 1992-2014 and 2015-2021

An updated index of abundance was developed for blue shark (Prionace glauca) from data collected by the U.S. pelagic longline fishery observer program (1992-2021). The U.S. pelagic longline CPUE was estimated for two separate periods (1992-2014 and 2015-2021) to account for changes in U.S. management regulations that could not be included in the standardization process. The indices were calculated using a two-step delta-lognormal approach that treats the proportion of positive sets and the CPUE of positive catches separately. Observations affected by fishing regulations such as time-area closures or bait restrictions were excluded in this analysis. The standardized indices with 95% confidence intervals are reported. The standardized index 1992-2014 showed an initial increasing trend from 1992 to 1998, followed by a decrease to 2003, an increase to 2011, and a subsequent decrease to 2014. The standardized index 2015-2021 showed an overall decreasing trend.