Please watch out for Pink Salmon on Tweed
With a report of a Pink Salmon having just been caught in the commercial nets off North East England, anglers and boatmen on Tweed should be on the lookout for any reaching Tweed.
As reported by Fisheries Management Scotland and the Salmon Boards last year, these fish spawn at a different time from Atlantic salmon, have a 2-year lifecycle and generally spawn in summer (and often in main river channels, in the lower reaches of rivers, and sometimes in upstream tributaries). Due to their 2 – year lifecycle, the progeny will be derived from distinct ‘odd’ or ‘even’ years, with the Russian/Norwegian fish being odd-year stocks (and we had reports in to the teens last year). Pink Salmon are less likely to be seen in ‘even’ years, but this is not completely out of the question, and the recent catch may mean that more turn up in the system.
Whilst it is theoretically possible that these non-native species could establish themselves in Scottish rivers, the higher water temperatures make this unlikely. Whilst the risks are not known, in terms of their interaction with Atlantic salmon and other native Scottish fish, they are unlikely to have a positive impact.
July is spawning time for these fish, and several were caught on the Tweed last year
These Pink Salmon (Oncorhynchus gorbuscha) have not come all the way from the Pacific! They were introduced to some Russian rivers around the White Sea in the 1960s and have since spread westwards and have now colonised some northern Norwegian rivers. There is also an introduced population in Newfoundland from which some rivers in Nova Scotia and Quebec have been colonised, but the most likely source of the fish that turn up in the Tweed will be northern Norway.
Breeding males are immediately identifiable because of their humps and they will almost certainly be running milt at this time of year. Their black tongues and heavily spotted tails are also very obvious. Females will show heavily spotted tails and be pinkish-brown on the flanks.
So far, no fresh Pink Salmon have turned up – they are steel blue to blue-green on their backs, silver on the flanks and white on their bellies. There are large black spots on the backs, upper flanks, adipose fins and tail – some of the spots on the tail can be as large as the fish’s eyes. They are very uniform in size, reaching only 40 to 60cms in length.
There is the possibility of breeding occurring in the Tweed, which would be highly undesirable. The species does not seem to have any great difficulty in spreading its range as shown by the way it has colonised rivers in northern Norway and eastern Canada from the original, man-made, introductions made to those areas. Their spawning zones are in the lower part of main channels, even in tidal reaches or, occasionally, in tributaries well upstream.
If you see what looks like Pink Salmon – and especially any spawning activity by them in Tweed during July and August – please inform the River Tweed Commission (RTC) immediately.