In the wake of footage recorded of the first invasive pink salmon seen in Scottish waters this year, the Missing Salmon Alliance has called on the public to report further sightings via online trusted platforms.

A new publication, The Blue Book, by the Atlantic Salmon Trust lists the spread of this invasive species as one of the key emerging threats to wild Atlantic salmon – alongside red skin disease.

Pink salmon, native to places like Alaska and Canada, were artificially introduced to the Atlantic after the Soviet Union transplanted and began stocking them in 1956.

For a long time, they were present in low numbers in the rivers of Norway, but now they are spreading to many other countries across the North Atlantic.

The Blue Book observes: “Norwegian rivers contained low and relatively stable numbers of reproducing pink salmon until 2017, when a significant movement of this fish, in a southerly direction, began across Europe”.

That year an unprecedented 139 pink salmon were spotted in Scotland, rising to 169 in 2021 (the fish tend to be more prevalent in odd-numbered years), and they have now already spawned successfully in both the rivers Ness and Thurso.

On Jun 29 underwater footage was recorded on the River Laxford in the Northwest Highlands by Chris Conroy, a filmographer whose salmon footage featured on David Attenborough's Wild Isles BBC series, and who is also the Atlantic Salmon Trust’s Technical Project Manager.

The Missing Salmon Alliance said that this early detection was  "testament to the extensive monitoring systems which have been installed as part of the 10-year landscape scale, ecosystem-wide, conservation project on the River Laxford catchment, run by the Atlantic Salmon Trust".

The alliance is encouraging others to report any sightings of Pacific pink salmon which will help inform wild Atlantic salmon conservation efforts.

Sightings, by anglers or the public, can be reported to Fisheries Management Scotland (FMS), the representative body for Scotland’s District Salmon Fishery Boards, via their Pink Salmon reporting app.

Last month a pink salmon was also caught in the River Dee.

The pink salmon is also known as the humpback salmon, due to the males' distinctive hump. They can also be identified by large black, oval spots on the tail, a bluish back, silver flanks and white belly, a very dark mouth with tongue, and the fact that they are smaller in size than the Atlantic salmon.

The Herald:

Migrating Atlantic salmon

Invasive non-native species are one of the top five drivers for biodiversity loss worldwide, and present a significant threat to native species and aquatic environments.

Atlantic salmon are already threatened. It is estimated that global populations of the species have declined from 8-10million in the 1970s to 3-4million today. That dramatic fall has been due to various pressures. This invasive species is believed to be an additional threat.

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Pink salmon were first observed in Great Britain in 1960, though in the 56 years leading to 2016 only seventeen were recorded in Scotland.

A recent paper titled ‘Prospects for the future of pink salmon in three oceans’ stated, “Pink salmon are now rapidly spreading in Europe and even across the ocean to North America. Large numbers of pink salmon breed in Norwegian rivers and small numbers of individuals have been captured throughout the North Atlantic since 2017.”

The report noted that the species' arrival could be “highly significant for native species.”

It said: “The invasion of pink salmon in the Atlantic basin is ultimately a massive ecological experiment and one of the first examples of a major faunal change in the North Atlantic Ocean that is already undergoing rapid changes due to other anthropogenic stressors.”

One of the report’s authors, Eva Thorstad, tweeted last week: “More than 200 000 invasive pink salmon have been caught in Norwegian rivers the last weeks, mainly in northern rivers where traps are installed to stop them. Twice as many as two years ago, and the migration season is not over yet."

In northern Scandinavia where invasive pink salmon are having a significant impact, the battle is already on. River managers are employing a range of extensive measures to remove them, including the use of artificially intelligent river gates that can only be opened by Atlantic salmon. That technology is now being considered for the UK.

The Missing Salmon Alliance says that it hopes that” by getting ahead of the curve in the UK, we can be better prepared for any similar increases in pink salmon here which may impact our already struggling native salmon.”