Gulf of Alaska | Fishes and Fish Habitats
Examining stress profiles and mortality rates of discarded Pacific halibut from a charter recreational fishery Presenter: Claude Dykstra , claude.dykstra@iphc.int, International Pacific Halibut Commission
Josep Planas , josep.planas@iphc.int, International Pacific Halibut Commission Allan Hicks , allan.hicks@iphc.int, International Pacific Halibut Commission Ian Stewart , ian.stewart@iphc.int, International Pacific Halibut Commission
Discard mortality rates (DMRs) are used to estimate the number of fish that die as a result of the combined stressors from the process of being caught, handled, and released. Charter (guided) recreational Pacific halibut fisheries in the central Gulf of Alaska involve high catch volumes (4-6 million lbs. annual landings) and have concurrently high discard rates (estimated 30 – 42% of retained catch). Assumed DMRs in this fishery are based in part on studies of mortality rates in the commercial longline fishery due to a lack of data from the recreational fishery. In an effort to collect industry relevant data, we conducted a field study on chartered recreational vessels in the Gulf of Alaska using common recreational fishing gear and capture practices to investigate (1) relationships among hook release injuries, physiological condition, and stress levels of captured Pacific halibut, and (2) post-release survival estimates. Physiological parameters collected included condition status at capture (condition factor, somatic fat levels) and post-handling stress indicators (plasma cortisol, glucose, and lactate). Short-term (i.e. 96 days) assessment of post-release mortality was investigated with the use of electronic survivorship Pop-up Archival Transmitting (sPAT) tags (not dependent on recaptures), while long-term survival is examined with the use of wire tags (dependent on recaptures). Results on the comparisons among hook treatments, environmental conditions, and physiological responses to capture stress, as well as on short-term post release mortality estimates will be presented. These results will be used to further refine the estimation of DMRs applied to the Pacific halibut charter recreational fishery.
Alaska Marine Science Symposium 2023 178
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