Biologists expect early 2018 Togiak herring run

Apr 11, 2018

Alaska Department of Fish & Game biologists are predicting an early herring harvest for the Togiak sac roe herring fishery.

ADF&G documented 37 miles of spawn along Togiak herring fishing grounds on April 17, 2016.
Credit Courtesy of the ADF&G

This year, Togiak could see one of the earliest herring harvests ever recorded.

“We’re going to fly our first survey on Friday. And then I expect we’ll be seeing herring by [April] 20th, if not sooner,” said Alaska Department of Fish & Game area biologist Tim Sands.

That would be the Togiak fishery’s second-earliest start on record. The earliest recorded date a biomass was spotted in the district was April 14, 2016. But because of the unusual timing, fishing only began three days later. Herring spawn timing depends largely on water temperature on the spawning grounds, and a warm spring means an early biomass arrival.

The total forecasted biomass for 2018 is 136,756 tons, slightly higher than last year’s forecast of 130,852 tons.

“We have a 20 percent exploitation rate,” said Sands. “So there’s 27,351 tons available to harvest.”

Of the predicted available harvest, 1,500 tons are allocated to the spawn on the kelp fishery. 1,810 tons are allocated to the Dutch Harbor food and bait fishery, which is harvested in July. The remainder of the predicted harvest is split between Togiak’s purse seine and gillnet fisheries.

Nineteen seine boats and three gillnet vessels are expected to participate in this year’s Togiak fishery. The purse seine fishery quota is 16,829 tons, or 70 percent. The gillnet fishery quota is 7,212 tons, or 30 percent.

The forecast is calculated with an age structured analysis (ASA) model to predict the herring population. Predictions are based on aerial surveys and harvest sampling, when biologists collect data on the age, sex, length and weight of the fish.  

“We look at amount of catch in each age class, and forecast a population for that age class,” said Sands. “By doing that year-in and year-out, we can look and see how much we think the age class is each year, and that helps us fine-tune the model.”

This year, the ADF&G enlisted a state-wide herring biologist to lead analysis efforts. The department also moved their model from an Excel spreadsheet to an AD Model Builder program. The program allows biologists to change the weights on the data to produce more accurate predictions.

“Before, the aerial survey was weighted higher, and the age composition was weighted lower. We reversed that, because we have more confidence in the age composition information than we do in the aerial survey information,” said Sands.

Sands said that pre-season talk put prices between $50 and $100 per ton, but he said that it is too early to know for certain.

“It’s all rumor at this point. It could be higher than that because of Sitka. But it might not make any difference. It all depends.”

The Sitka sac roe herring fishery shut down early this year after falling far short of its quota, which may push prices up in other regions.

Contact the author at isabelle@kdlg.org or 907-842-5281.