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Working Group on North Atlantic Salmon (WGNAS)

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posted on 09.09.2022, 10:06 authored by ICESICES

Amendments 8 September 2022: Added ToR 1.3 to 1.4., authors, list of participants and original resolutions.

Due to the extraordinary measure to cancel or postpone all Committee and Expert Group meetings, whether in-person, online or hybrid, scheduled between 7 March and 1 April 2022, the Working Group on North Atlantic Salmon (WGNAS), that was initially scheduled to take place in Copenhagen from the 28 March to the 7 April 2022 did not take place. However, some work was undertaken by WGNAS outside of this period and that work is reported here. Please refer to the WGNAS 2021 report for further information on the basis of the advice provided in May, 2022.

Pink salmon (Oncorhynchus gorbuscha) is a semelparous diadromous salmonid species, with a strict two-year lifecycle, and populations that spawn either in odd-or even-years. The natural range of Pink salmon in the Pacific and Arctic Oceans extends from 40°N to greater than 70°N, with the spawning distribution from 48°N (Puget Sound, Washington) to 64°N (Norton Sound, Alaska) in North America and from 44°N (North Korea) to 65°N (Anadyr Gulf, Russia) in Asia. The species has been introduced in various parts of the world, but only in the Great Lakes and in northwest Russia has Pink salmon established self-sustaining populations. The first attempts at introduction in the White Sea in 1957 failed to establish self-sustaining populations. In 1986 a second attempt using broodstock from a more northern location did establish self-sustaining odd-year populations in the White Sea and Kola Peninsula. Between 1960 and 2015 Pink salmon were regularly reported outside the area of introduction, with the majority of observations in the adjacent areas in the northern part of the Fennoscandian Peninsula. Occasionally reports were also made as far south as Scotland and Ireland. From 2017 Pink salmon have dramatically increased their range and abundance, with large numbers observed in the Barents- and Norwegian Seas, as well as rivers along the Atlantic coast of Norway and Finland where many also spawned. This increase in range abundance has been observed as far south as the Élorn river in France in NEAC and the Gander River in Newfoundland, Canada in NAC, with several hundreds of Pink salmon ascending rivers in Scotland, England, and Iceland. Some of these fish have been observed to spawn, for example in Scotland. This sudden increase in Pink salmon abundance has been linked with increases in Sea Surface Temperature (SST) in Arctic waters the winter before spawning. 

The appearance of large numbers of (spawning) Pink salmon in European, and even Atlantic Canadian and Greenlandic rivers in 2017, 2019, and 2021 has caused concern among fisheries managers that this could have a negative impact on wild Atlantic salmon stocks. It is difficult to establish with any certainty what the impact will be as research into this recent phenomenon is only now producing the first published results, and much of the effects will depend on the scale of the Pink salmon population increase in future years, which could be driven by uncertain factors such as Climate Change. Pink salmon can compete with Atlantic salmon for resources such as food and access to spawning habitat. In freshwater Pink salmon fry/smolts could compete with Atlantic salmon juveniles during their short stay and subsequent seaward migration, especially in rivers where they spawn farther upstream. In the marine environment large numbers of Pink salmon can cause trophic cascades in marine ecosystems, impacting on other species such as other salmonids. Density-dependent competition with Atlantic salmon for prey resources at sea could impact on growth, as it does with other salmonid species in the native range of Pink salmon. Increased nutrient loads in rivers and associated reduction in water quality as a result of decomposing Pink salmon carcasses after spawning could also impact on Atlantic salmon juveniles in freshwater. The threat of viral- and bacterial pathogens carried by Pink salmon to Atlantic salmon is poorly understood and therefore difficult to assess. 

It is also possible that some effects of Pink salmon on Atlantic salmon will be positive or neutral in nature, such as Pink salmon fry and ova providing a food source for Atlantic salmon juveniles or increased growth and survival in rivers enriched with nutrients from the Pink salmon carcasses left after spawning. 

Very little contemporary information regarding Atlantic salmon off the coast of East Greenland exists, although new studies are starting to provide some insights for this area. A series of marine surveys were conducted during the late 1960’s through the early 1970’s. Researchers concluded that the catch rates of Atlantic salmon were low compared to those at West Greenland, likely a result of a lower density of Atlantic salmon in the Irminger Sea. The biological characteristics of captured salmon were similar to those at West Greenland, suggesting that the salmon were using these two feeding areas in similar ways. However, there was a higher proportion of European origin salmon in the Irminger Sea and researchers hypothesised that as you move eastward, the proportion of European fish would increase. Subsequent tagging studies have demonstrated that salmon from Canada, Iceland, Ireland, Norway, UK (Scotland), UK (England and Wales), UK (Northern Ireland) and the United States all contribute to the harvest at East Greenland. Studies on post-spawned salmon show that northern European fish use this feeding area as well, although their distribution seems to be more northerly compared to salmon from southern Europe. The fishery off the coast of East Greenland is small, with an annual quota of three t set for 2021-2025 fisheries (Government of Greenland 2021) and reported landings averaging only 0.7 t per year since 2008. The low landings are assumed to be a result of the low human population density, which contributes to low fishing effort coupled with low density of Atlantic salmon off the coast of East Greenland. 

The Labrador and Irminger seas and their associated coastal waters have long been known to be important feeding areas for Atlantic salmon. Relative to the West Greenland, little is known regarding the stock composition, biological characteristics, etc. of salmon off the coast of East Greenland and the information that is available is from decades past. Given the decreased abundance of Atlantic salmon across the species’ range, a better understanding of the contemporary dynamics of Atlantic salmon off the coast of East Greenland is desired.

History

Published under the auspices of the following ICES Steering Group or Committee

  • FRSG

Published under the auspices of the following ICES Expert Group or Strategic Initiative

WGNAS

Series

ICES Scientific Reports

Volume

4

Issue

39

Contributors (Editors)

Dennis Ensing

Contributors (Authors)

Julien April; Hlynur Bardarson; Ida Ahlbeck Bergendahl; Geir H. Bolstad; Cindy Breau; Mathieu Buoro Karin Camara; Anne Cooper; Guillaume Dauphin; Dennis Ensing; Jaakko Erkinaro Peder Fiske; Marko Freese; Jonathan Gillson; Stephen Gregory; Nora Hanson; Derek Hogan; Niels Jepsen; Nicholas Kelly; Hugo Maxwell; David Meerburg; Michael Millane; Rasmus Nygaard James Ounsley; Rémi Patin; Sergey Prusov*; Dustin Raab; Etienne Rivot; Martha Robertson; Timothy Sheehan; Tom Stavely Ross Tallman; Alan Walker; Vidar Wennevik.

ISSN

2618-1371

Recommended citation

ICES. 2022. Working Group on North Atlantic Salmon (WGNAS). ICES Scientific Reports. 4:39. 39 pp. http://doi.org/10.17895/ices.pub.19697368