Justification
This species is listed as Least Concern in view of the large extent of occurrence (EOO), large number of subpopulations, large population size, and lack of major threats. The trend over the past 10 years or three generations is uncertain but probably relatively stable, or the species may be declining but not fast enough to qualify for any of the threatened categories under Criterion A (reduction in population size). It should be noted that treatment at species-level masks many significant declines that are in progress and well documented.
Geographic Range Information
This species has the widest natural range of all the Pacific salmon species. In Asia, the range extends from the Korean Peninsula north to the Arctic Ocean and west along the coast of northern Asia to the Lena River estuary to the Laptev Sea and Chaun Bay in the East Siberian Sea to the east up to the Bering Strait, to the south along the Asian coast up to the southern part of Korean Peninsula, including Kamchatka, the Kuril Islands and Japan (Hokkaido, Honshu and northern Kyushu). In North America, Chum Salmon occurred historically from the Sacramento River drainage, California (rarely the San Lorenzo River, southern California), to north-western Alaska, and east along the Arctic coast to the Anderson and Mackenzie rivers, Northwest Territories (Salo 1991). The species is now rare or locally extirpated from southern Oregon southward. Immatures are widely distributed over the North Pacific Ocean. See Frissell (1993) for a map indicating present and former distribution in the Pacific Northwest and California.
Population Information
In a survey of populations in the contiguous U.S., Huntington et al. (1996) identified 20 healthy native stocks, all in Washington. At least five stocks have been extirpated (Nehlsen et al. 1991).
Total adult population size is unknown but exceeded 45 million returning adults for the period 2005-2015 (Ruggerone and Irvine 2018).
The population trend varies with region. Many stocks in the southern part of the range are declining. It is apparently stable at low levels on the north coast of Oregon. In the Columbia River basin, it is apparently stable at about 0.5% of the historic level (escapement of about 2,000 individuals) (Nehlsen et al. 1991). In the Washington coast/Puget Sound area, the Chambers Creek early Chum Salmon escapement appeared to be rebuilding in the 1980s (Nehlsen et al. 1991). Of 1,625 stocks in British Columbia and Yukon, Slaney et al. (1996) categorized 23 as extirpated, 141 as high risk, 12 as moderate risk, 11 as special concern, 966 as unthreatened, and 473 as unknown status. See Frissell (1993) for a map indicating status/trend in different regions. See also NMFS (1998, 1999) for status of federally listed ESUs, which include the Threatened Columbia River ESU, and the Endangered Hood Canal Summer-Run ESU.
The Amur is the largest spawning river basin in the Chum Salmon range. During periods of high abundance, the Amur 'wild' Chum Salmon may represent more than 10% of the total in the Pacific Ocean. Over a period of about 120 years, the maximum number of Amur Chum Salmon has been recorded only twice. The maximum catch of summer-run Chum Salmon was in 1910 at 53 thousand tonnes (25 million individuals). During the depression period of 1940-2005, the catches fell to 0.5 thousand tonnes (0.3 million individuals). The maximum number of autumn-run Chum Salmon was also recorded in 1910 at 40,000 tonnes (12 million individuals). During the depression period 1970-2005, catches fell to 1,000-3,000 tonnes, with a stock of about 0.6 million individuals. Catch of autumn- and summer-run Chum Salmon increased in the 2010s. Thus, in 2015 the total catch was 35.7 thousand tons of Chum Salmon, and in 2016, 42.0 thousand tons. Artificial reproduction of Amur autumn Chum Salmon has existed since the first half of the 20th Century. There are five Russian salmon-fish hatcheries operating on the Amur River with a total volume of more than 100 million eggs released in recent years, and one Chinese hatchery. All salmon hatcheries are located far (150-1,500 km) from the mouth. This greatly reduces the efficiency of artificial reproduction of Amur autumn Chum Salmon (Kaev 2012, Antonov et al. 2019, North Pacific Anadromous Fish Commission 2020).
Habitat and Ecology Information
Chum Salmon spend most of their lives (2-7 years, usually 3-5 years) in the ocean. Adults return to spawn in streams where they hatched, sometimes moving up to 2,000 km upstream in rivers lacking major barriers in Alaska and Canada but usually spawning not far from salt water (usually within 100 km). Spawning occurs in gravel riffles in rivers and streams of various sizes. The female digs a redd, or nest, by displacing gravel and making depressions in an area of about 2.25 m2 (Moyle 1976).
Threats Information
This species is in jeopardy in Oregon and the Columbia River basin, evidently due to degraded water quality, incidental overharvest, and competition from hatchery fishes in streams (Nehlsen et al. 1991). It is nearly extinct in southern coastal Oregon due to overfishing and habitat damage. In the Columbia River basin, the population is reduced primarily by habitat degradation from forest and agricultural practices, urbanisation, pollution, and overharvest in mainstem fisheries directed at Coho and Fall Chinook (Nehlsen et al. 1991). In the Washington coast/Puget Sound area, populations in the Duwamish-Green and Elwha rivers generally are very small or extirpated due to habitat loss and degradation (Nehlsen et al. 1991).
Harvesting (using different fishing gear) of Amur autumn Chum Salmon is concentrated not only at the mouth of the Amur River. It starts on the northern coast of Sakhalin Island, then it continues upstream the Amur River. For 1,000 km up the river, fishing enterprises and the general public catch autumn chum salmon with floating and set gillnets. Above Khabarovsk Chum Salmon is caught by Chinese fishers. In 2017 and 2018 there was an unusually weak spawning run of Chum Salmon in the Amur River. Spawning grounds were filled up very badly. In these years, fishing rules on the Amur River were revised, and significant changes were proposed: the size of industrial fishing gear was reduced and the rules of their arrangement on fishing grounds in the lower reaches of the Amur River were changed (Antonov et al. 2009).
The main natural limiting factors for Amur Chum Salmon are changes in climatic conditions at spawning and sea feeding sites and eating out by predators, including marine mammals. Secondary factors are anthropogenic, mainly illegal fishing and barriers to migration to spawning grounds in rivers caused by “zaezdok” fishing gear, which comprises of a fence with nets (Kaev 2012, Antonov et al. 2019, North Pacific Anadromous Fish Commission 2020).
Use and Trade Information
This species is an important object of commercial, recreational and sports fishing.
Conservation Actions Information
Given the large distribution area of this species, it is likely to occur in multiple protected areas.
Certain local evolutionarily-significant units (ESUs; Columbia River ESU, Hood Canal summer-run ESU) are of conservation concern and are listed as Threatened pursuant to US Endangered Species Act (NOAA Fisheries 2020). It is included in the Red Book of the Amur Region due to the low number of species in the region (Antonov et al. 2009).
Waples and Teel (1990) emphasized the importance of monitoring the genetic consequences of the large-scale artificial propagation programs involving Pacific Salmon (see also Waples 1990). Meffe (1992) gave reasons why the hatchery approach to recovery ultimately will fail, and he emphasized that overharvest and habitat destruction need to be addressed in a major landscape-level effort. However, Kaev (2012) recommend increases in the hatchery approach in the Sakhalin-Kuril region, Russia to help recover wild populations and provide commercial fishing benefits.
See Nehlsen et al. (1991) for general protection and management recommendations for anadromous salmonids. See Thomas et al. (1993) for information on habitat management for this and other at-risk fish species in the Pacific Northwest.
Jasper et al. (2013) document evidence of genetic introgression of hatchery-origin chum salmon with natural populations in Prince William Sound, Alaska, and ongoing research in southeast Alaska is focused on understand hatchery-origin straying of chum salmon and potential affects on fitness of natural populations (Josephson et al. 2020). Recent estimates indicate that 60% of chum salmon in the North Pacific are of hatchery-origin (Ruggerone and Irvine 2018). Understanding the impacts of this level of hatchery supplementation on wild chum salmon, other Pacific salmon species, and marine food webs is an important area of research.
While focus on species-level status assessments are an important first step, the IUCN Species Survival Commission (SSC) Salmon Specialist Group (SSG) emphasizes the need to characterize status of Pacific Salmon at a more granular, population-level scale (identified as “subpopulations” in the IUCN Red List Guidelines) to provide meaningful guidance to stem the loss of biodiversity across the natural range of the species. There are many examples of declines in wild Pacific Salmon in both North America and Asia, particularly in the southern portion of their range given the degree of degradation and fragmentation of habitat there and the more immediate risk of climate change impacts. At the same time, there are large-scale ocean drivers that appear to be affecting species broadly across the North Pacific, regardless of their freshwater origin. Two excellent examples exist of assessment approaches and policies in the US (Waples 1991) and Canada (DFO 2005, COSEWIC 2018) that establish an effective framework for Pacific Salmon conservation. These efforts involve identifying population units based on a variety of criteria including examination of traits that are important in the evolutionary process and future adaptation. In these examples, assessments are conducted at a more granular, population-level, resulting in listings for individual population units, with identification of needed conservation actions specific to each unit. An example of assessing range-wide status of the species and at the individual subpopulation level in the IUCN Red List now exists for Oncorhynchus nerka (Rand 2011). While the amount of effort required to rigorously assess the species is substantial, we encourage efforts like this applied to the other species in the genus.
