Wednesday, March 10, 2021

IPHC Studying Recreational Discard Mortality

International Pacific Halibut Commission biologists are studying recreational discard mortality in Southeast and Southcentral Alaska to examine the impact of halibut release practices and associated mortality.

Participating charter vessels in areas 2C, in Southeast Alaska, and 3A, in Southcentral Alaska, must complete their recreational discard mortality sampling by June 30, the IPHC said.

The survey goal is twofold: the IPHC wants to evaluate effects of fish handling practices on injury levels and their association with the physiological condition of captured halibut. It also wants to investigate the effects of fish handling methods and associated injury level and physiological condition on post-release survival of these halibut in the guided fishery.

The IPHC issued a request for tenders for the study in early March, for vessels capable of carrying up to six anglers to take a minimum sample size of 240 Pacific halibut from each site targeted. The application deadline is March 19. More information is available at or by calling (206) 634-1838.

Each fish was to be measured, weighed, evaluated for injuries, sampled for blood and fat content, scored a survival viability and subsequently tagged and released. No fish are to be retained for consumption or other reasons.

Ian Stewart, a quantitative scientist with the IPHC, said the commission does stock assessments on an annual basis, and that right now discard mortality rates are part of the ongoing research. About 5-7% -- or one out of every 20 fish discarded – end up dead, he said. Given the large numbers of fish handled each year, this is one area where there’s a large amount of uncertainty, he said.

“The IPHC can make recommendations about handling processes and gear types,” he remarked. “We generally work with National Marine Fisheries Service and the North Pacific Fishery Management Council on this. It would be good to know if we could document differences in gear types, which gear causes the least harm to halibut,” he said.

“Halibut are an incredibly resilient fish, but nonetheless it’s still an appreciable amount of mortality. Regulations require minimizing mortality to the degree possible. The Alaska Department of Fish and Game recognizes different mortality differences,” he explained. “For example, the circle hook provides on average the least amount of damage. This study will help us better understand that.”

The 2021 study is a follow up to one done on commercial halibut fishery several years ago, where the IPHC stratified the fish into different injury rates, Stewart said. Information gathered during that study is still being evaluated.

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