As harvesters are witnessing changes at Ḵunáa Shak.áayi (Redoubt Lake), biologists with Sitka Tribe of Alaska and the U.S. Forest Service are supporting research, collaborating with partners and harnessing new artificial intelligence technology to prepare for uncertainties ahead.
Lively sockeye filled the falls at Redoubt Lake on most days this summer, as fishermen gathered there with dip nets, fishing poles and coolers. Sockeye from Redoubt provide food to many Alaskans and are central to Alaska Native ways of life.
This year’s Redoubt sockeye return is the largest documented in contemporary records. Technicians counted nearly 229,000 sockeye entering the lake while operating the Redoubt weir from mid-June to late July.
Previous record years were 2023 and 2024, with 153,406 fish and 210,253 counted, per USFS reports.
Redoubt Lake has changed in shape, flow and composition since 2013, when a massive landslide dammed the stream that feeds the lake.
In 2024, the Forest Service ceased its decades-long fertilization program at Redoubt Lake, which was geared at boosting prey availability for juvenile sockeye.
STA, the federally-recognized tribal government for Sitka, and the Forest Service are now working with scientists to understand how the landslide – and the fertilization program – affected the lake.
Meanwhile, STA is piloting new technology that could help reduce long-term costs of monitoring sockeye returning to Redoubt.
Ḵunáa (Redoubt) is an important village site belonging to the Kiks.ádi. It's a place where Tlingit people have long harvested salmon, herring, deer, berries and other foods.
Sealaska Corp., the Alaska Native Claims Settlement Act regional corporation of Southeast Alaska, announced in March that it had acquired 10.54 acres of USFS land at Redoubt by way of an ANCSA Section 14(h)(1) process that the corporation initiated in 1975.
In July, Sealaska and STA leaders signed an accord to continue working toward cooperative management of the important harvest site now that Sealaska owns lands surrounding the lake.
Lisa Gassman, the CEO of Sitka Tribe, said the government is proud to be partnering with Sealaska and Sealaska Heritage Institute to manage the site.
“It’s a groundbreaking agreement that empowers STA to manage the 10.54 acres of land above the high tide line at Ḵunáa,” Gassman said. “The agreement was made interim or short-term so that we can refine and redevelop it in future years to best address the needs of tribal citizens and non-Native Sitkans, while also protecting the rich historic site.”
The agreement does not bear on annual operations of the picket weir above the Redoubt Falls.
Weir operations, fishery management
Biologists with the STA and USFS collaborated this year to operate the Redoubt weir, and are working to ensure that weir operations continue.
Technicians work at the weir to count fish passing through each day, conducting random biological sampling, and marking about 3 percent of the fish with an adipose fin clip.
State fishery managers rely on in–season counts to make the escapement projections needed to liberalize harvest in the subsistence fishery at Redoubt, and to authorize the commercial fishery there.
Under the state’s Redoubt Lake Management Plan, subsistence limits rise to 25 sockeye per day and 100 per year only if sockeye returns are expected to exceed 30,000.
Commercial seining in Redoubt Bay is allowed when projections reach 40,000 fish. This year, seiners caught about 130,000 sockeye—the largest commercial harvest there since at least 1985, per Alaska Department of Fish and Game data.
Under a new regulation the Alaska Board of Fisheries passed this year, subsistence fishers were allowed use beach seine and gillnet gear once the 40,000-fish threshold was met.
People can obtain a community harvest permit once 40,000 fish are expected to return.
ADF&G Area Manager Aaron Dupuis said that without the in-season Redoubt weir count, it would be very difficult to implement the provisions of the management plan that hinge on accurate in-season projections.
Kyle Rosendale, deputy director of natural resources for STA, said that maintaining the weir is a priority for the STA because Redoubt provides a traditional food that’s an important part of haa kusteeyí (Tlingit way of life) and promotes food security for Sitkans.
“We want to make sure we can maximize the subsistence harvest opportunity at Redoubt Lake, so we want to make sure that we can keep the in-season monitoring going – I think that’s the biggest drive for us,” Rosendale said.
“Sockeye is an important part of our food,” said Harvey Kitka, Kaagwaantaan from the Multiplying Wolf House of Sitka. “We smoke some sockeye and jar it, it becomes part of our winter food. We put up some ‘fresh pack.’”
“Would you believe that sockeye were only a summertime food?” Kitka asked.
He said Tlingit people traditionally eat sockeye and coho in the summer; with lower oil contents, while pink and chum salmon can be dried and stored all winter.
Kitka said Redoubt is the most popular sockeye harvest site for Sitkans; it's a relatively safe 15-mile run from town; people can rely on good fishing when strong runs are returning there.
“It’s become so much easier to catch fish there,” Kitka said of the recent boom in returns.
Redoubt is the greatest source of sockeye salmon harvest for people in Southeast Alaska, Rosendale said. Based on unpublished USFS and ADF&G data, he found that about 35 percent of all subsistence sockeye harvest in Southeast Alaska happens at Redoubt.
A tribal needs assessment by STA in 2017 determined that salmon is the most important traditional food for tribal citizens, and that Redoubt is the most important place to get it, Rosendale said.
STA and USFS personnel have been working more closely together at Redoubt since 2023, when STA started processing a backlog of USFS’s Redoubt Lake water samples, and began cross-training staff to work on the Redoubt project, Rosendale said.
Beginning in 1982, USFS and ADF&G each year provided staff and resources to conduct the annual weir counts at Redoubt. ADF&G stopped working at the weir in the late 1990s; USFS ran the project from 1999 onwards, and Sitka Tribe of Alaska has supported the weir project since 2023.
Rosendale said STA is grateful for the partnership with the Forest Service to monitor Redoubt Lake sockeye. “We are working together to be more resilient altogether,” Rosendale said.
In 2024, USFS leaders indicated they didn't have funding to continue annual weir operations at Redoubt Lake, causing concern for many Sitkans.
After USFS pulled Redoubt funding in early 2024, leaders of STA took the issue to the Sitka Assembly and the local Alaska Department of Fish and Game Advisory Committee.
The city, the ADF&G Advisory Committee, Sitka Conservation Society, and Northern Southeast Regional Aquaculture Association wrote letters to Fish & Game and the state, imploring them to help fund the weir in 2024, Rosendale said.
The state paid for half of the shortfall in USFS funding in 2024, and local groups made contributions, Rosendale said.
Ahead of the 2025 summer season, STA identified funds for a significant portion of the supplies needed for the weir operation. USFS provided a majority of the staff needed, including interns from Sealaska Corp. and the WaterCorps; STA staff also worked the weir.
STA personnel are now working to make the project more affordable, and mitigate the risk of relying on grant funding for the project each year, Rosendale said.
Artificial Intelligence technology
New technology yields one possible solution. STA is currently testing an artificial intelligence video chute system that can count fish returning to Redoubt.
STA secured funding from the U.S. Fish and Wildlife Service in late 2024 to purchase equipment “that comes directly from a group called the SalmonVision collaborative, a group of First Nations, nonprofits, universities, industry partners that install these video monitoring sites,” Rosendale said.
This is the first time an artificial intelligence camera system is being used to count fish in-stream in Alaska, Rosendale said; the chutes are known to work well in British Columbia.
STA technicians installed the equipment at Redoubt in August, and recorded video there from Aug. 22 to Sept. 8. The AI camera system took 2,600 video clips in two and a half weeks; this winter, staff will watch a sample of the clips, and train the artificial intelligence model to discern sockeye from pinks and cohos, Rosendale said.
He said the SalmonVision video monitoring is meant to supplement staff at the weir, and make the project more sustainable in the long run.
“Certainly we don’t want to live year-to-year not knowing if there’s going to be a Redoubt monitoring project,” Rosendale said. “That’s hard on the community."
STA continues to seek grants and other funding for the weir project; USFS or ADF&G could pick it back up if the agencies’ funding changes, Rosendale said.
Kitka said that while he’s surprised by some of the changes lately, he’s glad to see STA personnel leading work at Redoubt.
“Its time our local people start taking care of what’s in their backyard,” Kitka said. “They’re here year-round, and it’s time for the tribe to take that extra step, to step up.”
“I hope to be a part of it,” Kitka said.
The end of fertilization
In recent years, the U.S. Forest Service stopped the fertilization program that it’s conducted at the lake since the early 1980s. It started the program with the fisheries rehabilitation division of ADF&G in response to depressed returns of less than 10,000 sockeye per year in the late 1970s, per a USFS management report.
To boost food availability in the lake, managers each summer began mixing thousands of pounds of fertilizer containing nitrogen, phosphorus and potassium into the lake. Fertilization occurred most years since the program began, and sockeye returns have increased.
USFS didn't fertilize Redoubt Lake in the 2024 or 2025 seasons and applied only half the usual amount of fertilizer in 2023.
In an email to the Sentinel, USFS Public Information Officer Paul Robbins Jr. said that, given record sockeye returns, the natural decaying process of the fish may provide adequate fertilization.
“Self-sufficiency in the watershed is the long-term goal,” Robbins said.
Studying changes since the landslide
STA is working with USFS, ADF&G and the University of Washington to study the biological and chemical composition of Redoubt Lake, and track changes over time.
Redoubt behaves very differently than most lakes, as it is meromictic, meaning the bottom of the lake is saltwater, and the top is fresh. The long, deep lake emerged some 700 years ago as the earth rebounded from glacial activity; it's the second-largest meromictic lake in North America.
The composition of the lake may have shifted after a landslide came down at the head of the lake in 2013, creating the smaller Luna Lake upstream from Redoubt Lake.
Beginning in 2014 until at least 2020, managers saw major blooms of bright, bluegreen cyanobacteria at Redoubt, which is unusual for any Alaskan lake, Rosendale said.
Dr. Michael T. Brett, a professor at UW who’s working with STA to study Redoubt, said that after the landslide came down “all sorts of crazy things started happening there.”
“There’s this giant cyanobacteria bloom, the zooplankton community shifts in a way that’s favorable for juvenile sockeye salmon and then all of a sudden sockeye salmon productivity goes up,” Brett said.
The change caused a boom in Daphnia, a zooplankton that functions like a cheeseburger for juvenile sockeye rearing in the lake, Brett said.
The lake’s Daphnia population exploded in 2015; sockeye returns jumped in 2017 and 2018, indicating that the Daphnia boosted sockeye productivity, Rosendale said.
However, Daphnia appeared to be declining in 2024, and Brett said that no Daphnia appeared in water samples that he took from the lake this summer.
Brett said the landslide also may have caused changes by mixing of the lake's freshwater and saltwater layers, and exposing tons of minerals.
And with salmon now decomposing in Luna Lake, their nutrients may be better utilized in the system.
“When the sockeye start disintegrating they create food for other things, which becomes food for them, the little sockeye,” Kitka said.
Climate change also affects sockeye survival in lakes and in the ocean, Brett said.
"It's possible that warming in general has made Redoubt Lake a better habitat for sockeye," Brett said. "Marine survival depends on how 'fat and happy' sockeye are going out as smolts."
Kitka said he’s not surprised by the large returns in recent years, as Tlingit oral history indicates Redoubt sockeye runs have been this large before.
Rosendale said that "what we don’t know is with these big returns, are they kind of a fortunate blip in time, or possibly a shift back toward the larger runs indicated by traditional ecological knowledge?”
Kitka emphasized the importance of studying the system year round.
“We should focus on finding out what the fish need in their habitat,” Kitka said.
