New research published on interbreeding between wild and cultivated salmon

The results of 10 years of research on interactions between cultivated and wild salmon in the Burrishoole Catchment, Co Mayo was published today in the scientific journal, Royal Society Proceedings B. The study provides the first scientific evidence that interbreeding between wild and cultivated salmon, either as a result of deliberate introductions of domesticated or non-native stocks, or accidental escapes of reared fish from salmon farms, could lead to the extinction of vulnerable wild populations of Atlantic salmon.

Dr Philip McGinnity of the Marine Institute and Prof. Andy Ferguson of the School of Biology & Biochemistry, Queen's University Belfast jointly directed the research at the Marine Institute research facility on the Burrishoole River System. The location for the study was selected because of the unique trapping systems and research facilities in the catchment, which has been a centre for salmon research for almost 50 years. Each salmon migrating in and out of the Burrishoole river system since 1970 has been monitored and recorded.

Dr Kjetil Hindar, a senior research scientist at the Norwegian Institute for Nature Research, and one of the world's leading fish geneticists, described the study as "…seminal…one of the most important studies on the genetics of salmonids carried out to date. A long-term study of the fitness of cultured salmon in the wild is unique and the results will be of major importance to those dealing with the biology and management of salmonid fishes throughout the world, as well as for other fish species being targeted for aquaculture."    

Mr Richie Flynn of the Irish Salmon Growers Association welcomed the study saying, "The fish farming industry is committed to a sustainable industry working in harmony with the environment.  The Irish industry was pleased to facilitate this study and we therefore welcome its publication as a valuable contribution to the long-term management of the wild salmon and aquaculture industries.  While escapes of farmed fish in Ireland have historically been very low, the industry will take note of the report in adhering to the strict protocols agreed by ISGA members to prevent farm escapes. It is hoped that those who manage river systems will also take note of the consequences of their actions in restocking those systems. "

It is estimated that some two million Atlantic salmon escape each year from fish farms in the North Atlantic. In Ireland, however, the level of escaped farm salmon has been consistently low for the last number of years and therefore does not pose a significant threat to the wild population. Intensive monitoring of commercial catches of wild salmon by the Marine Institute, which each year examines some 100,000 fish, has shown that farm escapes in Ireland represent less than 1% of total commercial catches. 

The investigation also contains important findings relating to the management and enhancement of wild salmon stocks. The study concludes that deliberate stocking of cultivated or non-native salmon is likely to be more damaging than accidental escapes. Therefore the study has significant implications for salmon and trout stocking policies in Ireland and internationally. 

"The findings of this important study are fundamental to the future management of impacts of salmon aquaculture on the wild salmon stocks," said Dr Malcolm Windsor, Secretary of the North Atlantic Salmon Conservation Organization (NASCO), which is the international treaty organisation concerned with conservation of wild salmon stock. "The results confirm that NASCO and its Contracting Parties were correct in taking precautionary measures, in the absence of adequate scientific advice to protect the wild stocks from genetic and other biological impacts both from escapes from salmon farms and from poorly planned stocking from hatcheries.  The study will greatly assist in quantifying impacts and in safeguarding the wild stocks in future".

Dr. Peter Heffernan, CEO, Marine Institute welcomed the publication of the scientific paper in Royal Society Proceedings B saying, "This work demonstrates the capability of Ireland to undertake world class marine research and highlights the global significance of the Marine Institute R&D facilities in the Burrishoole catchment in Newport Co Mayo."

The experiments examined multiple families of first and second generation hybrids between wild and farm salmon in the freshwater and marine life phases and DNA profiling was used to identify the parentage of individuals. The study demonstrates that where the number of farm escapees is high relative to the wild stocks, interbreeding has genetic and competitive impacts on wild salmon populations.