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Scientists will collect data on Unalaska’s salmon at new weir this summer

Maggie Nelson
The structure of the Iliuliuk Creek weir will be essentially the same as the one at McLees, just with fewer fish. It will sit just below the outlet of Unalaska Lake, behind the senior center.

Updated 06/25/24 11:15 a.m. This story has been updated to reflect new and more accurate information provided by the Alaska Department of Fish and Game.

The Alaska Department of Fish and Game and the Qawalangin Tribe were unable to get funding to count fish and collect data this summer at Unalaska’s McLees Lake, where the community harvests a large majority of its subsistence sockeye salmon.

But the organizations will be installing a brand new weir and counting salmon for the first time at Iliuliuk Creek.

Annie Brewster, a fisheries biologist with ADF&G, said the Qawlangin Tribe is leading the project, and together, they will be counting the number of pinks and reds that make it up the creek and into Unalaska Lake.

We're expecting to get around 6500 pink salmon and around 500 sockeye salmon,” Brewster said.

Run size can vary greatly from year to year, and the weir will give the most accurate escapement data to date, she added.

Those numbers are based on past foot and aerial surveys, which don’t provide as accurate data as the weir, according to Brewster.

She said weirs provide the most accurate data as they are not affected by things like turbidity, cloudy weather or shadows, or several layers of fish. In a weir, technicians physically count the fish as they pass through a small gate, while collecting samples and data on the salmon.

Still, Brewster said aerial surveys are a very useful tool. Drone surveys, specifically, provide helpful data and are less time and resource intensive than weirs, she said. When scientists have both weir and drone data, she said they can develop a drone index, which is a comparison of how many fish they count using the drones and how many they count with the weir.

“So, for example, if we pass 10,000 sockeye salmon through a weir during year X, but with a drone survey during year X we only count 8,000 sockeye, that allows us to calculate an index for a drone survey on that particular lake/creek,” Brewster said. “And we could expect that if we were to do a drone survey during year Y and we did not have a weir during year Y, the number of fish counted via drone survey would probably only be 80% of the true number of fish.”

She said it takes multiple years of data from both weir and drone research to establish an index like that.

The banks of Unalaska lake are eroding, contributing to the haziness, or turbidity, of the water, which has also been polluted from World War II activity.

There is still a lot of solid waste from the war,” Brewster said. “There were suspected chemical barrel dumps during the war into the lake.”

She said there has also been known “blue-stoning” in the lake, which is the addition of a copper sulfate substance to the water that prevents algae growth and is detrimental to lake life.

ADF&G weir technicians won’t just be counting salmon. They’ll also be collecting data on the limnology of the area — that includes things like water quality and zooplankton.

That provides us with information on the rearing capacity of the lake,” Brewster explained. “So at what capacity can the lake raise baby salmon? What's the number of salmon eggs that can be laid in beds and gravel nests in the lake and grow up to be mature salmon that will return to the stream?”

She said gathering data on water quality could help the Qawalangin Tribe secure future funding for the restoration and remediation of Unalaska Lake.

Fish and Game and the Qawalangin Tribe received some federal funding from the National Oceanic and Atmospheric Administration for the new weir. Brewster said she hopes next year they can secure full funding from NOAA to help the tribe eventually fulfill their goal of performing some of that restoration work.

Fish and Game and the tribe didn’t receive funding from the Office of Subsistence Management, through the Fisheries Resource Monitoring Program, for the island’s McLees Lake weir this season. That means they won’t be monitoring the salmon run there.

Technicians have been counting salmon at McLees, located at Cape Wilsow on the north end of the island, for more than 20 years. It closed for two years in 2018 because the organization couldn’t secure funding and reopened again in 2020.

The McLees weir is an important resource for subsistence harvesters in Unalaska. Brewster said it’s unfortunate that it won’t be operational this summer, but it’s also great to have a weir in town.

That will kind of encourage people to come stop by, ask questions, see what's going on, learn more about the project,” she said.

The structure of the Iliuliuk Creek weir will be essentially the same as the one at McLees, just with fewer fish. It will sit just below the outlet of Unalaska Lake, right behind the senior center.

Technicians and officials with Fish and Game are scheduled to arrive on the island Wednesday and begin installation on Friday.

There won’t be any in-season management at McLees this year because there’s no weir. That means harvesters will have hard limits on when and where they can fish. In previous years, regulators could open fishing up to the mouth of the river when they saw enough fish pass through.

“This year, because we won't have any data on the escapement during the season, that's just going to be pushed out to that outer marker from July 1 through July 9, regardless,” Brewster said.

During those nine days, harvesters can’t take fish within 500 yards from the mouth of the stream.

There is no escapement goal for the Iliuliuk weir yet, so the project shouldn’t affect any subsistence fishing limits or regulations in that area, she said.

The first step for this weir is getting more reliable data to help inform fisheries management down the road.

Part of the initial aim of this project is really to start collecting data — start building a data set that will allow us to understand the size of the salmon run there, what species, what's the timing of the run, what's the rearing capacity of the lake, and all of that information can help us set an SEG — a sustainable escapement goal,” she said.

Brewster said that will likely take a few years. She said she hopes they can secure funding for both weirs next year.

Correction: This story previously stated that ADF&G and the Qawalangin Tribe received funding for the McLees Lake weir from the Alaska Sustainable Salmon Fund. It has since been updated with the correct information.

Hailing from Southwest Washington, Maggie moved to Unalaska in 2019. She's dabbled in independent print journalism in Oregon and completed her Master of Arts in English Studies at Western Washington University — where she also taught Rhetoric and Composition courses.
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  • Unalaska City School District students released around 1,400 hatchery-raised silver salmon into Iliuliuk River May 23. They began working with the fish in November, with river surveys starting in August.
  • New data from drone surveys flown over Unalaska’s three road-system lakes last summer show low sockeye salmon counts. The counts total less than half of what they were in summer of 2020, according to data released in April by the Alaska Department of Fish and Game. But Fish and Game biologist Tyler Lawson said the one-year drop isn’t too concerning. Escapement numbers often fluctuate and there’s more room for error in aerial surveys, he said. “We call them a ‘high error survey,’ which kind of sounds bad, but it's just because in comparison to the weir — which is a very precise tool — there's variability whenever you're up in the air, looking down and trying to count salmon,” he said. While the technology is still relatively new when it comes to counting salmon in Unalaska, Lawson said he’s hopeful that drones will play a key role in helping assess broader trends among salmon stocks in the region.
  • On April 1, a young humpback whale was found tied up in a probable fishing line and anchored down in a busy area in Iliuliuk Bay. Four days later, a group of whale entanglement experts carefully cut the line wrapped around the humpback's mouth and tail.