October 29, 2003
Ireland's Research Shows Interbreeding Between Farmed & Wild Salmon Could Wipe Out Atlantic Salmon Population
A latest report researched by scientists in Ireland claims that interbreeding between farmed and wild stocks could wipe out vulnerable Atlantic salmon populations.
An estimated two million salmon escape each year from fish farms in the north Atlantic; this is equivalent to about half the total number of wild adult salmon in the sea.
Scottish Executive figures show there were 450,000 escapes from Scottish fish farms last year and so far this year registers 96,000 escapes.
According to a ten-year study by scientists in Ireland, the genetic make-up of wild stock is affected when they breed with cultivated salmon, possibly reducing survival rates.
Professor Andrew Ferguson from Queen's University Belfast and Dr Philip McGinnity from the Galway-based Marine Institute, led the study using salmon research facilities on the Burrishoole river system in Co Mayo.
Prof Ferguson said: "Escaped salmon can enter rivers where they interbreed with wild salmon, thereby potentially changing the genetic make-up of wild populations of Atlantic salmon. The importance of such changes in the survival of the remaining wild populations has been a matter of debate for the past decade but little scientific evidence has been available - until now," he said.
Dr Paulo Prodohl, one of the researchers with the project, the results of which were published in the scientific journal Royal Society London Proceedings B, said the experiment showed that farmed salmon have both genetic and competitive impacts on wild populations.
"The results of this project have provided a convincing and clear warning to the people involved. The farm industry is now starting to address the problem and work together with the government to avoid such high numbers of escapes and we hope that it will become more controlled," he said.
The Scottish Wildlife Trust says it is concerned by the report. It says while Scottish Quality Salmon (SQS), the industry promotional body, has issued guidelines on containment, many fish farms are not members of the body.
But SQS says there is little evidence to suggest that fish-farm escapes even end up in Scottish rivers. Brian Simpson, SQS's chief executive, said: "In reality, farmed salmon have poor chances of survival once they escape. In fact, only 191 farmed salmon were among the 57,920 wild salmon and grilse caught by anglers in the recently published 2002 Scottish statistics.
"If, as the report suggests, the degree of impact is directly related to the abundance of farm escapees and the relative wild spawning stock, proactive river stock restoration with wild fish strains, such as that done in Scotland, would counter this.
"Of course, everyone is working to avoid escapes of farmed salmon, not least salmon farmers, and there are stringent SQS codes of practice to minimise this occurrence with our member companies."
Mr Simpson added: "Scottish Quality Salmon member companies will continue to collaborate with river owners and fisheries trusts, and look forward to playing an active part in the protection of Scotland's wild salmon stocks."
SQS says there are certain factors that can affect the decline of wild salmon stocks. This includes over-fishing, illegal angling techniques, rising sea and river temperatures, lack of food, predators, poaching, pollution and river rerouting.