2021 Yukon Area Fall Season Summary

This announcement provides a preliminary summary of the 2021 Yukon Area (Figure 1) fall chum and coho salmon run size and escapements. All results are considered preliminary.

2021 Fall Season Outlook

The fall chum salmon run size forecast, using brood year analysis, was for 652,000 fish, with a range of 542,000 to 762,000 fish. A preseason run size projection was made in mid-July using the relationship between historical summer and fall chum salmon run size estimates. Using the estimate of 157,000 summer chum salmon, the preseason projection for a fall chum salmon was a run size of less than 184,000 fish.

The coho salmon outlook for 2021 was for a near average run size of 240,000 fish. The outlook assumed an average survival of fish from the 2017 parent year, however recent trends have been run sizes below average.

Last edited 12/27/2021
Contact Information

Christy Gleason, Area Management Biologist

Bonnie Borba, Fall Season Research Biologist

Shane Ransbury, Assistant Area Management Biologist

(907) 459-7274

Preseason Management Strategy

Management of the Yukon Area fall season salmon fisheries are in accordance with the Yukon River Drainage Fall Chum Salmon Management Plan (5 AAC 01.249). The plan requires that when a projected run size is less than 300,000 fall chum salmon, all subsistence, personal use, sport, and commercial directed chum salmon fisheries shall close. The plan also requires a run size of at least 550,000 fall chum salmon to allow directed commercial fishing on surplus fish above that level.

Based on the preseason projection of less than 300,000 fall chum, preseason management strategies included the following:

  • Concurrent with the fall chum salmon migration upriver, all Yukon Area districts and subdistricts would remain closed to subsistence fishing unless the run projection exceeded 300,000 fish.
  • To improve fall chum salmon escapement to the spawning grounds, the Alaska Department of Fish and Game (department) anticipated implementing a complete closure of subsistence salmon fishing in the Alaska portion of the Porcupine River, including the tributaries, as the fall chum salmon migration reached that area.
  • Commercial salmon fishing would not be allowed unless the inseason drainagewide fall chum salmon run projection exceeded 550,000 fish, and a commercial surplus was identified.

2021 Run Assessment

Assessment information collected from projects located in the lower river were used to inform management decisions. The projects included two lower river drift gillnet test fisheries that provided run timing and relative abundance information, and a mainstem Yukon River sonar, located near the community of Pilot Station, that provided fish abundance estimates. Stock composition information for chum salmon was provided by genetic samples collected at the mainstem Yukon River sonar. Upriver projects that monitored escapement consisted of a mainstem Yukon River sonar operated near the U.S./Canada border; Teedriinjik (Chandalar River) sonar, an upper Porcupine River sonar; a weir/sonar/video project operated in the Fishing Branch River, a Porcupine River headwater tributary; foot surveys conducted in the Delta River, a tributary of the Tanana River; boat surveys in the Delta Clearwater River, a tributary of the Tanana River; and aerial surveys in the Tanana River drainage. Age, sex, and length information was collected at the lower river test fisheries, the mainstem Yukon River sonar near the U.S./Canada border, and from the Fishing Branch and Delta rivers.

By regulation, the fall season began in District 1 on July 16, and chum salmon caught after that date in the Lower Yukon River Drift Gillnet Test Fishery (LYTF) are considered fall chum salmon. Mountain Village Drift Gillnet Test Fishery (MVTF) began operating on July 18, and the mainstem Yukon River sonar, operated near the community of Pilot Station, began counting fall chum salmon on July 19. The transition of upriver districts and subdistricts to the fall season management was based on the migration timing of fall chum salmon. The LYTF completed operations on September 10 (Yukon Delta Fisheries Development Association assisted throughout the season and conducted all drifts in late August through the end of the season) and resulted in a preliminary cumulative fall chum salmon catch per unit effort (CPUE) of 125.72, which was well below the historical median of 1,588.86. The MVTF project ceased operations September 12 with a preliminary cumulative fall chum salmon CPUE of 450.29, which was well below the historical median of 2,038.58. The mainstem Yukon River sonar near Pilot Station ceased operations on September 7.

After July 19, six groups of chum salmon were monitored entering the Yukon River (Figure 2). The first group that entered in July contained a mixture of summer and fall chum salmon. After that, predominantly fall chum salmon entered the river. The preliminary chum salmon passage estimate at the mainstem sonar project near Pilot Station was 146,172 fish, which was well below the historical median of 723,000 fish. Applying mixed stock genetic analysis to all the chum salmon that passed the mainstem sonar after July 18, the estimated number of fall chum salmon was near 102,000 fish.

Throughout the fall season, the run size tracked below the 300,000 fall chum salmon threshold necessary to allow subsistence fishing (Figure 2). Run timing for fall chum salmon in the lower river assessment projects was nearly four days later than average and upriver escapement projects were two days later than average. Water levels were generally average to below average during the fall salmon migration within the Alaska portion of the Yukon River drainage.

Coho salmon appeared to be weak and late through the entire run (Figure 3). The preliminary coho salmon passage at the mainstem sonar was estimated to be 37,000 fish, which was well below the historical median of 147,000 fish (Figure 3), and the lowest ever observed at this project. The preliminary run size index was estimated to be 45,500 coho salmon, which includes estimates of passage after the sonar concludes for the season. Both the preliminary cumulative CPUE for coho salmon at the LYTF and MVTF were well below their respective historical medians and represent new record lows for the projects. Run timing for coho salmon was four days later than average across all the assessment projects.

Subsistence Fishery

This year’s low fall chum and coho salmon runs, on top of poor summer season salmon returns, led to extreme hardships for subsistence fishermen relying on these critical resources along the Yukon River. The Alaska Department of Fish and Game and U.S. Fish and Wildlife Service staff want to extend our gratitude for the commitment of fishermen to conserve salmon runs for future generations during low abundance years. We recognize the extreme hardship these salmon fishing closures place on food security, especially during the pandemic. While we understand there is no replacement for salmon, we tried to provide other fishing opportunities during this difficult year while implementing necessary restrictions and closures to conserve salmon for future years. We also want to thank everyone for their participation in the preseason and inseason Yukon River Drainage Fisheries Association (YRDFA) teleconferences. The input and information managers receive during the teleconferences is invaluable.

The 2021 fall chum salmon preliminary estimated run size of 102,000 fish was the lowest on record for the second consecutive year. With last year’s unexpected poor fall chum salmon run size of 194,000 fish, the 2021 run strength was uncertain. After observing the record low summer chum salmon run this year, it became apparent the fall chum salmon run was going to be worse than last year. This was based on the strong relationship between summer and fall chum salmon run abundance trends, a tool that allows refinement of the fall chum salmon projection just prior to the fishing season.

The fall season began with a revised fall chum salmon projection of less than 300,000 fish. In accordance with the Yukon River Fall Chum Salmon Management Plan, all fishing (subsistence, personal use, sport, and commercial) was closed from the beginning of the fall season. As the season progressed, the fall chum salmon run projection dropped to 102,000 fish compared to an average run size of 1 million fish. Coho salmon also returned at a record low abundance with only 37,000 fish passing the mainstem sonar.

Managers coordinated with fishermen and YRDFA inseason teleconference callers to find ways to provide some opportunity for other salmon species. Subsistence fishing opportunity was provided with selective gear types (dip nets and hook and line) for pink, sockeye, and coho salmon that are present in the Lower Yukon Area. While using selective gear, all chum salmon were required to be released alive. Fishing for important non-salmon species, such as northern pike, whitefishes, and burbot, remained open throughout the Yukon River drainage with various gears.

As the season progressed, it became apparent that the body size of fall chum and coho salmon was the smallest observed in the historical datasets and the percentage of female fall chum salmon was trailing about 10% below average in Lower Yukon assessment projects. Due to the higher probability of encountering smaller bodied salmon and females, 4-inch or smaller mesh gillnets that are used to target non-salmon species were placed on a reduced schedule to allow more salmon to reach their spawning grounds. To provide more fishing opportunity during this time, subsistence fishing opened with fish wheels (manned) for non-salmon, while fall chum salmon were required to be released alive immediately, and coho salmon were strongly recommended to be released as well.

Once the tail end of the salmon runs had passed, subsistence fishing restrictions were relaxed. However, to protect spawning salmon, important spawning areas for fall chum and coho salmon in Yukon River drainage tributaries will remain closed to subsistence salmon fishing through the end of December.

The preliminary subsistence harvest of fall chum salmon was estimated to be 703 fish, which is well below the 2016–2020 average of 60,861 fish (Table 1). The preliminary subsistence harvest of coho salmon was estimated to be 293 fish, which is well below the 2016–2020 average of 6,078 fish (Table 2). These subsistence harvest levels are unprecedented, creating extreme hardships for fishermen relying on this resource.

Commercial Fishery

There was no commercial fishing in the Yukon Area during the fall season, in 2021. Historical harvest, value, and numbers of permits in the fall chum and coho salmon fishery can be found in Tables 3-6.

Salmon Escapement

Fall Chum Salmon Escapement

The total run size of fall chum salmon is estimated postseason, based on information from individually monitored spawning escapements and includes estimated U.S. and Canadian harvests. Escapements were monitored using sonars in the Teedriinjik (Chandalar) River, upper Porcupine River in Canada, and Canadian mainstem Yukon River (near Eagle; Table 7). In 2021, the preliminary estimate of the drainagewide total run size is near 100,000 fall chum salmon and even without the removal of the estimated small harvests this season the escapement is nowhere near the sustainable escapement goal (SEG) range of 300,000 to 600,000 fish. The final run reconstruction estimate will be determined using the Bayesian statistical methods once the subsistence harvest estimates are completed.

Fall chum salmon escapements in 2021 were approximately 10% to 30% of the lower end of escapement goals at all assessment projects. In the Teedriinjik River the estimated escapement of 21,162 fall chum salmon (including expansions to estimate the run after the sonar project ended) was below the sustainable escapement goal (SEG) range of 85,000 to 234,000 fish (Table 7) and a new record low for this project. An estimated run size of 13,000 fall chum salmon in the Sheenjek River was derived from using the relationship of Sheenjek River sonar counts and Fishing Branch River weir. An estimate of 3,486 fall chum salmon was counted past the Porcupine River border sonar downstream of Old Crow and border passage was estimated to be 3,465, after removal of Old Crow harvests. The Fishing Branch River weir estimate was approximately 2,413 fall chum salmon which was well below the lower end of the Interim Management Escapement Goal (IMEG) range of 22,000–49,000 fish (Table 7). The fall chum salmon passage estimate at the mainstem Yukon River sonar project near Eagle was 18,671 fish (90% CI: 19,268–20,068) for the dates September 1 through October 6. The fall chum salmon estimate was subsequently adjusted to 23,170 fish, which includes estimated passage after the project was concluded for the winter. The preliminary escapement for the mainstem Yukon River in Canada is derived by subtracting the upstream U.S. and Canadian harvests above the Eagle sonar project from the expanded sonar estimate (in 2021 there was no U.S. or Canada harvests reported due to conservation measures). The preliminary mainstem Yukon River escapement estimate of 23,170 fall chum salmon is well below the IMEG range of 70,000 to 104,000 fish (Table 7), which is also a new record low.

The Tanana River preliminary escapement estimate was 43,000 fall chum salmon based on mixed stock analysis, ranking near the lowest escapement for this system. The estimated escapement in the Delta River of 1,613 fall chum salmon was a new record low and was well below the SEG range of 7,000 to 20,000 fish (Table 7). The escapement into the Delta River, particularly the mainstem, may have been partially affected by environmental factors resulting in the latest run timing of the fish moving into the system from the mainstem Tanana River.

Fall Chum Salmon Age, Sex, Length and Stock Composition

Stock composition estimates for chum salmon were provided by USFWS Conservation Genetics Laboratory using tissue samples (fin clips) collected from salmon captured in the mainstem Yukon River sonar test net fishery. Chum salmon genetic samples processed from three strata between July 19 and September 7 (fall season) indicated that stocks represented were approximately 31% summer, 28% Border U.S. (Teedriinjik/Sheenjek/Draanjik), 12% Canadian, and 29% Tanana.

In 2021, the proportion of age-3 (3%) fall chum salmon was average, age-4 fish (87%) was above average, age-5 fish (9%) was below average, and age-6 fish (<1%) was below average based on samples collected at the Lower Yukon Test Fishery using 6-inch mesh drift gillnets. The 2016 and 2017 brood year estimates of return per spawner of 1.16 and 0.47, respectively, are both below the 1974–2014 average of 1.76. Females contributed 54% of the samples which was slightly below the 1986 to 2020 average (58%). Fall chum salmon length samples in 2021 averaged 562 mm, well below the long term 1981–2020 average of 593 mm.

Coho Salmon Escapement

There are few coho salmon spawning escapement assessment projects in the Yukon River drainage because of funding limitations and late timing relative to onset of winter. The sonar in the mainstem Yukon River near Pilot Station was operated through September 7 and had an estimated passage of 37,257 coho salmon (SE 2,359) which is well below the historical average of 147,000 fish. The Delta Clearwater River (DCR) has the only established escapement goal for coho salmon, a SEG range of 5,200–17,000 fish. A series of boat surveys were conducted on the DCR, with the peak count occurring in early November with an estimated 913 coho salmon, which was well below the escapement goal (Table 8). Escapement estimates for coho salmon were conducted by aerial surveys in the Nenana River drainage; all four spawning areas counted were below their respective 2011–2020 averages (Table 8).

Coho Salmon Age, Sex and Length Composition

In 2021, very few coho salmon were captured in either LYTF and MVTF therefore samples sizes for age, sex, and length were extremely small. The few samples (n=49) that were collected represented mostly small male coho salmon. The greatest number of length samples of coho salmon (n=411) were collected from the test fishery associated with the mainstem sonar operated near Pilot Station. Coho salmon in 2021 in this project averaged 520 mm in length (based on all mesh sizes operated) and ranked second smallest compared to the 1995–2020 average of 558 mm.

Perspectives on Low Returns

In 2021, the fall chum and coho salmon returns to the Yukon River were the lowest on record for a second consecutive year. The primary parent years of the 2021 runs for fall chum salmon were 2016 and 2017, and 2017 for coho salmon. The parent years that produced these last two years of poor runs met or exceeded escapement goals for both salmon species, including meeting the fall chum salmon IMEG at the Fishing Branch River in both 2016 and 2017 (Tables 7 and 8). Of note, the parent years for this year’s fall chum and coho salmon run were exceptional, ranking second largest since 1975 for fall chum salmon and third largest for coho salmon (Figure 4).

The reason for the critically low returns during 2020 and 2021 is currently unknown. Stocks of both species within the entire drainage and across dominant age classes (ages 4 and 5) are being impacted. The species experienced dramatic declines despite their different life histories, where chum salmon migrate to the ocean shortly after hatching to spend 2–5 years at sea, and coho salmon remain in freshwater for 1–3 years and then spend 1 year at sea before returning.

This year’s poor chum salmon runs were not unique to the Yukon River. Chum salmon runs throughout Western Alaska, including the Kuskokwim River and rivers in Norton Sound, also came in well below preseason forecasts in 2020 and 2021. It is likely that the factors and conditions impacting Yukon River fall chum and coho runs this year also impacted other eastern Bering Sea salmon stocks. The department is committed to investigating the cause of the recent Pacific salmon declines, especially to the Yukon River Area. Research updates are shared on https://www.facebook.com/ADFGUnderseaWorldOfSalmonAndSharks.

If you have further questions on upcoming marine salmon research efforts, contact Dr. Katie Howard, kathrine.howard@alaska.gov and Sabrina Garcia, sabrina.garcia@alaska.gov.

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