Pink salmon (Oncorhynchus gorbuscha)

The pink salmon is native to river systems flowing into the North Pacific Ocean, the Arctic Ocean and the Bering Sea between Siberia and Alaska. During their breeding migration from the sea to spawn in freshwater streams, rivers and intertidal areas, usually in late-summer to mid-autumn, the males develop a pronounced humped on their back, so pink salmon are sometimes also known as humpback salmon. The females dig redds in gravels, cover them over after spawning and then guard them; the adults do not return to sea but die soon after spawning. The juveniles hatch the following winter and make their way to sea the following spring. The adults feed at sea but return to rivers to spawn after only one winter at sea. 

Because they die after spawning once (a semelparous species), this means that pink salmon populations typically have a two-year life cycle for migration and spawning: pink salmon born in odd-numbered years generally do not spawn or interbreed with those born in even-numbered years. 

Stockings introduced to support commercial fisheries in northwest Russia have established populations in northwest Russia and northern Norway, and this migratory species occasionally strays westwards and southwards from this range. In 2017, pink salmon were caught in Ireland, mostly in rivers in the West, and elsewhere in Europe in unprecedented numbers, and they reappeared in 2019, 2021 and 2023.  

Pink salmon differ from Atlantic salmon in following ways:

• Large black oval spots on the tail
• Anal fin has 11-19 rays (Atlantic salmon have 7-11)
• Much smaller scales than similar-sized Atlantic salmon
• No dark spots on the gill covers
• Upper jaw typically extends beyond eye

Inland Fisheries Ireland is closely monitoring the occurrence of pink salmon in Ireland's rivers and collecting samples to assess whether they have the potential to spawn and become an invasive species. Anglers are asked to keep and freeze any pink salmon they catch and to report them to Inland Fisheries Ireland by calling 0818 34 74 24 (open 24 hours a day, 7 days a week) without delay.

IFI is now using environmental DNA (eDNA) sampling to monitor Irish rivers for invasion by pink salmon in the PINKTrack project.