Statistical and Monte Carlo analysis of the Hawaii deep-set longline fishery with emphasis on take and mortality of Oceanic Whitetip Shark

The study developed a process model from pelagic observer data to describe the take and mortality of oceanic whitetip shark (OCS) in the Hawaii deep-set longline fishery. The process model considered the: 1) probability of interaction (Catch model #1); 2) probability of branchline bite-off (Catch model #2); 3) probability of mortality at retrieval (Fate model #1); 4) probability of mortality due to handling between retrieval and release (Fate model #2); and 5) probability of post-release mortality and mortality of bite-off (Fate model #3). Three scenarios were considered for the OCS process models: 1) the current fishery use of using wire leaders and leaving ~10 m of trailing gear on a released shark (Scenario 1-Status quo); 2) intended use of monofilament, removing all trailing gear (0 m) on a released shark (Scenario 2-Monofilament leaders); and 3) intended use of monofilament, removing all trailing gear (0 m) on a released shark and gear modification by eliminating three hooks adjacent to longline floats (Scenario 3-Monofilament leaders and gear modification). Monte Carlo simulations were conducted for each of the three scenarios. 2021 NMFS (National Marine Fisheries Service) PIFSC (Pacific Islands Fisheries Science Center) Submitted https://doi.org/10.25923/a067-g819 Public Domain 1904