State fisheries officials are forecasting a potential 2021 harvest of 47,348 tons of herring in all Togiak fisheries and 42,639 tons in the Togiak sac roe purse seine and gillnet harvest, under the 20 percent exploitation rate.
Greg Buck, area research biologist for the fishery, said that the 2021 mature herring biomass forecast is 236,742 tons, the highest forecast since 1993, when the age-structured assessment model was implemented. The increase in forecast biomass compared with previous years is due to the high percent of partially mature age classes observed in 2020.
The forecast percentage composition of the mature population in 2021 is mostly comprised of ages 5 through 8 fish both by numbers and by biomass. The forecast average weight of a fish in the 2021 mature population is 291 grams whereas the average weight of a fish that is vulnerable to the commercial purse seine fishery is 314 grams.
ADF&G officials said they obtained an aerial survey estimate of peak biomass in 2019 and 2020 with confidence ratings greater than zero, but that there is considerable expected uncertainty in the 2021 forecast due to uncertainty in the large estimated age-4 recruitment in 2020.
The survival and overall magnitude of that year class (2016) is highly uncertain, and it remains to be seen if the large age-4 recruitment event results in a large increase in the expected number of mature age-5 fish in 2021 relative to the number of mature age-4 fish in 2020, they said.
