Updated standardized catch rates in biomass for the North Atlantic stock of blue shark (Prionace glauca) from the Spanish surface longline fleet for the period 1997-2021

Standardized catch rates per unit of effort (CPUE) were updated for the North Atlantic stock of blue shark (Prionace glauca) using Generalized Linear Models (GLM). A total of 15,795 trips (94.6% of coverage) of the Spanish surface longline fleet catching swordfish between 19972021 period were analyzed. The main factors considered were year, quarter, area, gear and the targeting strategy. The base case model explained the 83% CPUE variability in weight. Most of the variability was explained by the proxy of the targeting criteria of skippers followed by gear factor. Other factors were also significant, but less important. The standardized CPUE show an increasing trend until 2008 and remains stable since then to 2021.