Standardized catch rates of blue sharks in the western North Atlantic Ocean from the US pelagic longline logbook and observer programs

Updated indices of abundance were developed for blue shark (Prionace glauca) from two commercial sources, the US pelagic longline logbook program (1986-2013) and the US pelagic longline observer program (1992-2013). Indices were calculated using a two-step deltalognormal approach that treats the proportion of positive sets and the CPUE of positive catches separately. Standardized indices with 95% confidence intervals are reported. The logbook time series showed a decreasing trend, dominated by a steep decline in the first few years of data, until the mid-2000s, followed by an increasing trend thereafter. The observer time series also showed a decreasing trend from 1992 to 2003, followed by an increasing tendency thereafter.