Commercial herring fisheries in Prince William Sound will remain closed through June 30, 2023, due to estimated spawning biomass being below threshold, say area biologists with the Alaska Department of Fish and Game.
Under the Prince William Sound Herring Management Plan, a minimum spawning biomass threshold is 22,000 tons, and no fishery may be opened if this estimate is not met.
At projected biomass estimates, between 22,000 tons and 42,500 tons may be allowed by ADF&G based on age-class strength, a harvest of herring at an exploitation rate between zero and 20%.
Biologists at the University of Washington School of Aquatic and Fishery Sciences calculated a preliminary estimate of 26,202 short tons for the 2022 PWS spawning biomass.
It is the largest estimate since 2009 and is 98.3% above the 10-year average (2012–2021) of 13,216 short tons.
While this year’s preliminary estimate is within the range for consideration of a guideline harvest level, the fishery will remain closed because estimated biomass of recruit-age fish is unlikely to offset older age class mortality and conservative management is warranted, state biologists said.
Multiple years of above threshold biomass estimates and signs of improving recruitment will be needed before a fishery is opened.
Preliminary spawning biomass estimates incorporate an age, sex and length sample size of 763 herring and will be updated once all samples are processed and aged. Preliminary unweighted age composition for 2022 PWS spawning biomass is 18% age-3, 10% age-4, 14% age-5, 55% age-6, 2% age-7, 1% age-8 and <1% age-9+.
Age-6 fish are the majority of this unweighted age composition estimate and recruit-age fish (3-4 years old) continue to represent a small portion of the population.
ADF&G officials said they wanted to thank community members who helped with the collection of 2022 samples, the University of Washington for development and operation of the research model and funding for the assessment provided by the Exxon Valdez Oil Spill Trustee Council.
