Collecting water samples for eDNA detection of pink salmon.


Co-ordinated environmental DNA (eDNA) surveillance programme for pink salmon in the European Union.

Pink salmon (Oncorhynchus gorbuscha), also known as humpback salmon, are native to river systems flowing into the North Pacific Ocean, the Arctic Ocean and the Bering Sea between Siberia and Alaska. Like Atlantic salmon, they spawn in late-summer to mid-autumn in freshwater streams, rivers and intertidal areas but migrate to sea in springtime to spend their adult life feeding in the open ocean. Pink salmon return to rivers to spawn after spending just one winter at sea, and they die after spawning. This means that populations typically have a two-year life cycle, returning to rivers every other year and thus occurring in odd-year or even-year populations.

In 2017, pink salmon were recorded in Irish rivers, and they have returned in every odd year since then (2019, 2021 and 2023). In anticipation of the potential re-occurrence of this non-native fish species in 2023, IFI commenced an environmental DNA (eDNA) surveillance programme to detect the presence of pink salmon in key catchments located throughout Ireland. This programme has become the basis of IFI's involvement in PINKTrack, an EU-funded project co-ordinated by IFI and supported by the North Atlantic Salmon Conservation Organisation (NASCO).

Pink salmon caught in Galway, 2017.

Where Did Pink Salmon Invade From?

Pink salmon were introduced to rivers in northwest Russia flowing into the White Sea and the Barents Sea in stocking programmes to support commercial fisheries since in the 1950s, and they established populations in this region that spawn in the wild principally in odd years. There were other stockings in the Baltic Sea, Black Sea, Caspian Sea, southern Norway and eastern North America, but these failed to establish self-sustaining populations.

Prior to 2017, pink salmon generally occurred outside of this introduced range as very low numbers of strays, but in 2017, they irrupted into the North Atlantic Ocean in unprecedented numbers and over a much wider, more westerly and more southerly geographic area along the Atlantic coast of Europe, as well as Iceland and Greenland.

Potential Impacts

This increase in the abundance and geographic distribution of pink salmon is thought to be correlated with increases in water temperature, which helps the growth and survival of both juveniles in freshwater rivers and adults in marine environments. The homing instinct of pink salmon to return to their natal river is not as strong as in Atlantic salmon, which may result in a higher proportion of pink salmon straying outside their established range in good years for the species when their abundance is high. It is anticipated that pink salmon will continue to expand their range as increased water temperatures due to climatic warming continues in the future.

NASCO and EU member states are concerned that the further spread and establishment of non-native pink salmon around the North Atlantic is an emerging threat to native wild Atlantic salmon. There is currently limited information on the ecological interaction between pink salmon and Atlantic salmon, which makes it important to develop an 'early warning system' to detect when pink salmon invade a river and to monitor their impacts on Atlantic salmon stocks.  

Pink salmon caught in the River Moy, June 2023.

PINKTrack Project

PINKTrack aims to develop an eDNA sampling protocol for national monitoring programmes in EU member states and is comprised of four work packages (WPs); IFI will play a lead role in co-ordinating and delivering WP2 and WP3:

  • WP1 — eDNATrack: Development of standardised protocols for eDNA sampling for the detection of pink salmon in routine national monitoring programmes.
  • WP2 — SurveillTrack: Establishment an eDNA sampling programme for detection of pink salmon to elucidate spatiotemporal patterns of spread and to provide an 'early warning system' for national monitoring programmes.
  • WP3 — ProjectTrack: Organisation of project workshops to discuss protocol development, disseminate results, review outputs, promote adoption by national monitoring programmes, etc.
  • WP4 — Project Management & Co-ordination

PINKTrack is funded by the EU to run from November 2023 to October 2026.

Collecting water samples for eDNA detection of pink salmon.