“Will Placentia Bay aquaculture affect native salmon?”, the author claimed “there has been no undisputed evidence to date of direct effects of salmon aquaculture on wild populations.” This is patently false; there is a wealth of scientific evidence that demonstrates clearly and conclusively that net pen salmon aquaculture has significant negative impacts on wild salmon.
For example, in March, the International Council for the Exploration of the Sea (ICES) held a workshop with 25 of the world’s leading scientists on the issue of wild/farmed salmon interactions. They reviewed over 150 scientific studies into the impacts of aquaculture on wild Atlantic salmon populations and published a report which concluded that “there is substantial and growing evidence that salmon aquaculture activities can affect wild Atlantic salmon, through the impacts of sea lice and farm escapees” and that both factors can reduce the productivity of wild salmon populations. That report is on the ICES website.
Further evidence comes from global study by researchers at Dalhousie University (J. Ford, R. Myers, 2008) that assessed changes in marine survival of salmon and sea trout in association with increasing production of salmon aquaculture. They found the presence of salmon aquaculture resulted in a reduction of survival and abundance of wild salmon populations, in many cases greater than 50 per cent, and concluded that “salmon farming has reduced survival of wild salmon and trout in many populations and countries.” This study is on the Public Library of Science website.
In Newfoundland, both DFO and the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) have concluded that aquaculture has had negative impacts on salmon populations on the south coast (where salmon populations have been assessed as threatened by COSEWIC) and remains a threat to their long-term survival and recovery. In assessing the recovery potential, DFO stated, “Even small numbers of escaped farmed salmon have the potential to negatively affect resident populations, either through demographic or genetic changes in stock characteristics. There have been many reviews and studies showing that the presence of farmed salmon results in reduced survival and fitness of wild Atlantic salmon, through competition, interbreeding and disease.” The recovery assessment report is available through the Canadian Science Advisory Secretariat.
Last month, DFO scientists revealed the results of a new study that confirmed widespread mating between wild salmon and aquaculture escapees in 17 south coast rivers, which they believe has led to reduced productivity and abundance in those populations. It is not surprising we are seeing impacts from salmon farms locally given the results of a recent study by Gardner Pinfold Consultants showing that this province has some of the weakest aquaculture regulations in the North Atlantic when it comes to protecting wild salmon from the impacts of salmon farms (report is on the Atlantic Salmon Federation website).
After many years and hundreds of studies, we are past debate over whether or not aquaculture has negative impacts on wild salmon stocks. The science is conclusive, and we must assume that any new aquaculture development will have negative impacts. The burden of proof is now on the aquaculture industry and the governments that promote it to demonstrate that salmon farms have minimal impacts, and to ensure that new developments proceed with good scientific baseline knowledge of local environments and the salmon stocks they support, and with robust science-based monitoring programs to ensure that any impacts that do occur are known, understood and mitigated.
Dr. Stephen Sutton
Atlantic Salmon Federation