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- Salmon
- Indicator
- Number of natural-origin summer chum salmon on spawning grounds
- Vital Sign Indicator
- Each Unit (number)
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No targets are currently set for this indicator.
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Neala Kendall
- Contributing Partners
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- Last Updated
- 3/6/2023 1:57:58 PM
This indicator evaluates the abundance values and their trends of the two Hood Canal summer-run chum salmon populations as measured by the number of natural-origin adult fish on the spawning grounds. Abundance estimates here do not include hatchery-origin fish or fish taken in harvest or by predators like orcas. The indicator is intended to reflect the goal of achieving wild population recovery of Hood Canal summer chum, which are federally listed as threatened.
Annual percent change in spawner abundance from 1999 to 2021 for two Hood Canal summer chum salmon populations (Hood Canal and Strait of Juan de Fuca). The lines show the 25th to 75th credibility intervals (CIs). CIs represent a range of values the true annual percent change likely falls within.
Hood Canal summer chum salmon are a cultural icon of the Pacific Northwest and are listed as “Threatened” under the federal Endangered Species Act (ESA). Returning summer chum are prized by anglers and commercial fisherman, are guaranteed to be available to Indian Tribes by treaties signed with the federal government, and are an important part of their ecosystem.
- Hood Canal summer chum salmon abundance has increased in both populations since they were listed as threatened under the ESA in 1999. Therefore, our conclusion about progress of the Hood Canal summer chum populations is “Getting Better.”
- Estimates of population spawner abundance of the two Hood Canal summer chum populations have increased (statistically significantly for one population, though not for the other) since the baseline reference period when the populations were listed in 1999.
- One population remains below its low productivity threshold for low risk of extinction (the recent 5-year abundance geomean for the Strait of Juan de Fuca summer chum population is at 72% of its threshold), the other population is far above this threshold (the Hood Canal summer chum population is at 243% of its threshold; see the indicator map).
- Monitoring Program
Summer chum salmon spawner abundance data are collected annually by WDFW and tribal co-manager staff as part of baseline monitoring and data collection efforts.
- Data Source
Washington Department of Fish and Wildlife (WDFW), Salmon Population Indicators (SPi) abundance data
Biologists typically estimate annual spawner abundance by counting the number of redds (gravel nests) in a river each year. Redds are counted by walking the stream or from boats or aircraft. In many populations, some hatchery-origin salmon are present on the spawning grounds along with natural-origin salmon, complicating the estimates of natural-origin abundance. The proportions of spawners that were of natural versus hatchery origin are typically estimated based on the composition of carcasses of each origin. These proportions are applied to the total spawning population to estimate the number of natural-origin versus hatchery-origin spawners.
Summer chum salmon population spawner abundance is reported here as the number of natural-origin fish estimated on the spawning grounds (spawning naturally) for all populations. There are two NOAA Fisheries-defined distinct independent populations (DIP; generally known as “populations”) in the Hood Canal summer chum salmon evolutionarily significant unit (ESU): Hood Canal and Strait of Juan de Fuca.
Our analysis of abundance change over time answers the question:
Has the spawner abundance of each summer chum salmon population changed compared to their abundance in 1999 when Hood Canal summer chum were listed by NOAA Fisheries under the Endangered Species Act (ESA)?
We chose ESA listing in 1999 as the baseline reference period because this date denotes the start of deliberate management efforts to improve the status of the population. It should be noted that the 1999-2003 period was one of relatively favorable ocean conditions (i.e., a “cool” PDO phase) for Hood Canal summer chum salmon, where we would expect better marine survival than during a warm PDO phase.
In this trend evaluation, we fit a multivariate autoregressive state space random walk with drift (MARSS-RWD) model to the log of population spawner abundance data for all populations from 1999 to 2021. The model structure was identical to that used by NOAA Fisheries’ Northwest Fisheries Science Center in its recent two 5-year status review with a few exceptions (Northwest Fisheries Science Center, 2015 and 2022). The slope of each population's smoothed abundance values was converted to percent change per year. If data were not available during these periods for a given population, data from the first or most recent years with available data were used.
To assess each population’s spawner abundance levels and to calculate a percent of threshold abundance, we compared their recent 5-year geometric mean (“geomean”) of smoothed abundance data from the MARSS-RWD model to their low productivity threshold for low risk of extinction. Planning thresholds for summer chum salmon abundance have been estimated for both low and high productivity scenarios. At low productivity, the population needs to be larger compared to that at high productivity in order to survive and be resilient to poorer habitat and environmental conditions, changes, and catastrophes. We evaluated the recent 5-year geomeans relative to the low productivity threshold because the populations are thought to be in a low productivity phase, and it is a more conservative assessment. Find more information on summer chum planning targets for abundance and productivity in the Final Supplement to the Hood Canal and Eastern Strait of Juan de Fuca Summer Chum Salmon Recovery Plan (2007).
For more information about the methods used for this indicator, please see the Status and Trends Analysis of Salmon Abundance Data methods report.
References:
Northwest Fisheries Science Center. 2015. Status review update for Pacific salmon and steelhead listed under the Endangered Species Act: Pacific Northwest.
Northwest Fisheries Science Center. 2022. Biological Viability Assessment Update for Pacific Salmon and Steelhead Listed Under the Endangered Species Act: Pacific Northwest.
- Critical Definitions
- Natural-origin fish: fish produced by parents spawning in natural environments (not in a hatchery)
- Natural-origin adult fish on the spawning ground: fish produced by parents spawning in natural environments that themselves returned to spawn in a natural environment
- Population spawner abundance: number of natural-origin summer chum salmon estimated on the spawning grounds in a population
- Hatchery-origin fish: fish produced by parents spawned in a hatchery
- Endangered Species Act (ESA): Hood Canal summer chum salmon were listed as Threatened under the ESA in 1999. There are 2 NOAA Fisheries-defined distinct independent populations (DIP; generally known as “populations”) in the Hood Canal summer chum salmon evolutionarily significant unit (ESU)
- MARSS-RWD: multivariate autoregressive state space random walk with drift model, which was the statistical model used in our analyses
One of two Hood Canal summer chum salmon populations is currently below its low productivity threshold for low risk of extinction needed for population recovery while the other is far above its threshold (Table 1; L. Lestelle, pers. comm.). Both populations’ escapement abundance has increased since ESA listing in 1999.
NOAA Fisheries is the federal agency responsible for the recovery of ESA-listed salmonid species. They report trends as part of their status reviews every 5 years. In their most recent available status review (Northwest Fisheries Science Center, 2022), they analyzed the trend over a continuous time period from 2004 to 2019 using a similar model employed for the time trend analysis described in the methods section above. NOAA Fisheries found that natural-origin spawner abundance values of both Hood Canal summer chum salmon populations increased from 1990 to 2005 but did not increase in the 2004 to 2019 period (due in large part to recent declines since 2017). They concluded that the Hood Canal summer-run chum salmon ESU remains at “moderate” risk of extinction, with viability largely unchanged from the prior review (Northwest Fisheries Science Center, 2015 and 2022).
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Population Name |
2017-2021 Geomean |
Threshold for Low Risk of Extinction |
Geomean % of Low Productivity Threshold* |
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High Productivity |
Low Productivity |
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Hood Canal |
10,506 |
4,100 |
4,327 |
243% |
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Strait of Juan de Fuca |
3,121 |
3,400 |
4,350 |
72% |
| *(5-year geomean/low productivity planning target)*100 | ||||
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Salmon recovery in Puget Sound has been guided over the years by collaborative processes. The Hood Canal & Eastern Strait of Juan de Fuca Summer Chum Salmon Recovery Plan was developed by regional experts and adopted by NOAA Fisheries in 2005 to meet obligations under the Endangered Species Act. A Final Supplement to the Recovery Plan was adopted in 2007.
Continued investments in restoring salmon habitat in and around streams and rivers, significantly reduced harvest rates, and revisions in hatchery management have resulted in significant progress in increasing Hood Canal summer chum salmon abundance.
Chum salmon utilize a variety of habitats, from freshwater (though less than other species) to the ocean, and are therefore vulnerable to stressors associated with change and degradation of habitats across a large area. Many of the factors already implicated in the lack of recovery of chum salmon are exacerbated by the bio-physical impacts of climate change. From the Northwest Indian Fisheries Commission 2020 State of Our Watersheds Report:
"A consistent trend identified in the 2020 State of Our Watersheds Report is that key habitat features, such as riparian vegetation, habitat connectivity and streamflows, continue to be imperiled by human activities. This extensive loss and degradation of habitat, changing climate and ocean conditions threaten salmon, tribal cultures and tribal treaty-reserved rights, wildlife habitat, water quality and western Washington’s economy and quality of life."
Salmon Vital Sign Indicator Reporting Plan
Recreation and Conservation Office's State of Salmon in Watersheds Report and Salmon Abundance Dashboard
Northwest Indian Fisheries Commission State of Our Watersheds Report
NOAA Fisheries Hood Canal & Eastern Strait of Juan de Fuca Summer Chum Salmon Recovery Plan
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- Reporting Instructions
No Subcategories for this Puget Sound Indicator.