Threat to NI's wild salmon

Mike McKimm
BBC NI environment correspondent

The future of wild salmon is being put in jeopardy by specially bred farm salmon, according to the latest report by Irish scientists who are warning of an "extinction vortex" if the problem is not tackled soon.

After an intense 10-year research programme, scientists have published results which show that the farmed salmon interbreeding with the wild stock result in a hybrid that has a poor survival record in the sea.

This means that even fewer salmon result in the next generation and their survival ability becomes even more limited.

Farm salmon are breeding with wild salmon and risking the latter's survival

Salmon that escaped from farms had a survival rate of just 2% compared to that of wild salmon.

But when they managed to get into rivers, the farm salmon were strong competition for the wild species, often destroying critical food stocks and making the habitat untenable for the wild salmon.

Another worrying statistic from the research is the death of 70% of all embryos resulting from second generation of inbreeding. This provides a very low survival rate for any species.

The research was a joint project between Queen's University, Belfast and the Marine Institute in County Mayo, in the Irish Republic.

They used special DNA finger-printing techniques developed in Belfast for recognising specific fish.

The researchers have estimated that the wild salmon population, mainly in northern European waters, is about four million fish.

But a further two million escaped farmed salmon are also at sea in any one year.

The worst escape of fish was in the Faroe Islands last year when 600,000 salmon escaped after a storm.

The report also warns against the restocking of rivers with farm salmon.

Research shows that this can be even more devastating to the wild salmon.

The research suggests that the numbers of young salmon in any river or lake where this happens actually drops because there is a poor survival rate.

Paulo Prodohl said the data could not be ignored

"If escapes continue to occur, the results of our research clearly demonstrates that extinction is a real possibility, said Paulo Prodöhl, a researcher from Queen's University Belfast, one of the report's co-authors

"It is especially true in cases where populations are already being threatened by a number of other factors.

"We cannot ignore this data. We have to do something about it."

The research is bound to cause controversy, especially in Scotland where salmon farms and fish escapes are numerous.

"While a farm salmon will add about £1.50 to the economy, a wild salmon will add hundreds of times that amount," said BBC Northern Ireland environment correspondent Mike McKimm.

"Rod fishing for salmon is big business worth tens of millions of pounds. And often when the fish is caught, they throw it back, so it starts earning all over again."