State fisheries biologists are forecasting a 2020 Togiak commercial herring harvest of 43,165 tons, with 30,999 tons, or 80 percent for the purse seiners and 7,750 tons, or 20 percent, for the gillnetters.
A harvest of this size would be approximately 188 percent of the recent 10-year average sac roe harvest, state biologists said
Last year the allocations gave 21,544 tons to the seiners and 5,386 tons to the gillnetters.
The Alaska Department of Fish and Game’s Division of Commercial Fisheries said that the 2020 forecast is using a 20 percent exploitation rate because the department has greater confidence in the 2019 aerial survey biomass estimate than those of the last three years.
The state has been estimating the Togiak mature herring population biomass with aerial surveys since the late 1970s, but the combination of poor data and state budget cuts resulted in fisheries biologists lacking confidence in available data for 2016 through 2018, so they were basing the harvest allocations on a 14 percent exploitation rate, said Tim Sands, an area management biologist at Dillingham. Then in 2019 they got good data, felt more confident and went back to the 20 percent exploitation rate for the 2020 allocations, he said.
Sands noted that the herring fishery at Togiak is occurring earlier and earlier each year, with starts as early as mid-April, compared to early May back in the early 2000s, but the impact of warming ocean waters and ocean acidification on various stages of the herring life cycles is still an unknown, he said. “We had warm years in the early 200s and then it switched in 2006 to colder winters and the herring season started a little later and spring was a little later, and there was more sea ice, until 2013. After that it seemed like we had earlier and earlier springs and warmer winters,” he said.
The 2020 forecasted biomass should be similar in size to the 2019 biomass, and like this past year be dominated by partially mature age-6 and age-7 fish, the state said in its forecast.
These cohorts of young fish are projected to comprise an even larger portion or the population in 2020, due to increasing maturity. The projected average weight of a herring in the 2020 harvest is 329 grams.