Expert claims angling is cause of Scottish salmon decline.
A fish-farming expert and industry supporter has claimed that the blame for the decline in Scottish salmon lies not with fish farming but with anglers, after airing a controversial theory about our sport’s impact on the gene pool of the species.
Dr Martin Jaffa, a fish-farming consultant based on Manchester, has submitted a report to the Scottish government’s aquaculture and fisheries bill consultation stating that the widely held theory that the interbreeding of farmed and wild salmon is to blame for weakening the species’ DNA is incorrect. Instead, he claims, that it is in fact the impact of decades of anglers removing fish from the gene pool that has resulted in ‘genetic drift’ and the decline in the numbers of salmon returning to Scottish rivers.
According to Dr Jaffa the findings that the interbreeding of wild and farmed salmon are to blame for an increase of wild fish being unable to survive at sea and return to spawn are inconclusive. He instead believes that it is actually years of the removal of breeding salmon from rivers by anglers that is to blame through its affect on the species’ gene pool. This genetic depleting of the species, he claims, is the cause for the changing of thousands of years of behavior in Scottish salmon, and the source of the decline in wild salmon survival rates.
"Genetic drift is caused by random events that occur by chance. As a result, some individuals have a greater impact on the population than might be expected,” said Dr Jaffa. "This is because other individuals might die suddenly and unexpectedly and cannot contribute to the 'pool of genes' of the whole population.
“In wild salmon populations, such a sudden and random loss might be associated with the catching and killing of salmon by anglers over the last 150 years. Over the last 10 years about 350,000 potential breeding salmon from Scotland's rivers have been killed by rod anglers.
"This number would have been much higher had it not been for the recent introduction of a catch-and-release policy on many rivers."
However, the theory has already been dismissed by many. Nick Chisholm, Director of the River Annan Fisheries Board and Trust, described the report as ‘bizarre’ with the breeding of escaped farm fish with wild fish being the obvious cause of changes in genetics of Scottish salmon.
“A number of years ago some eminent scientists in Ireland did some work looking at the survival of fish-farm-bred fish in the wild and they discovered their survival rate…was a couple of orders of magnitude below that of wild fish. “So if farmed fish get into a river and they breed with wild fish, you introduce these survival traits.”
Paul Knight, Chief Executive of the Salmon and Trout Association Scotland also found the claims unbelievable “The Salmon & Trout Association Scotland recently published a review of 137 scientific papers that showed the damage that is inflicted on wild salmon and sea trout from poorly sited and operated salmon farms, a fact that is borne out by the problems experienced in Norway and accepted as requiring urgent remedial action by the Norwegian Government,” he said. “Rather than trying to engineer this issue as a fight between fish farmers and anglers, Dr Jaffa would be better served working towards resolutions which would allow a successful fish farming industry to co-exist alongside healthy and self sustaining populations of wild salmon and sea trout. “That is the wish of my association and, I suggest, all those who have a respect for these wonderful and iconic natural resources.”