Standardized Catch Rates of Shortfin Mako Shark (Isurus oxyrinchus) caught by the Hawaii-based Pelagic Longline Fleet (1995-2019)

Catch and effort data from the Hawaii-based pelagic longline fishery operating in the North Pacific Ocean were analyzed to estimate indices of abundance for the shortfin mako shark between 1995 and 2019. The data come from the records of the Pacific Islands Regional Observer Program (PIROP) submitted to the Pacific Islands Fisheries Science Center (PIFSC). Nominal CPUEs were calculated separately for shallow-set (target: swordfish) and deep-set (target: bigeye tuna) sectors, and standardized with Generalized Linear Models (GLM), separately for each sector. Model validation was carried out with residual analysis. The best-fit models included variables year, quarter of the year, region, sea surface temperature, bait type, and interactions between quarter of the year and region. Overall, the standardized CPUE for the deep-set sector showed a stable trend from 1995 to 2016, followed by an increase in the last three years, while the standardized CPUE in shallow-set sector showed a slightly decrease up to 2012, followed by an increase in 2013.