Net Pen Aquaculture
Puget Sound contains commercial salmonid net-pen aquaculture facilities, including eight large facilities that grow marketable-sized Atlantic salmon (exotic to Puget Sound). Net-pen fish harbor parasites and disease-causing organisms that can infect wild fish. In 2012, at the exact time wild salmon juveniles were migrating through Puget Sound, three Atlantic salmon net pens suffered from an outbreak of Infectious Hematopoietic Necrosis virus (IHNV). While thousands of net-pen fish died, the permits issued to the facilities do not require wild fish populations to be monitored for virus exposure. Both state and federal agencies promote aquaculture as a “sustainable” use of public waters, but the public does not have a clear sense of the risks.
Research in northern Europe, Chile, and Canada indicates that net-pen aquaculture poses serious risks to wild fish, but in the Puget Sound region, the risk is rarely acknowledged in recovery-planning efforts. Because native juvenile salmon must pass through Puget Sound as they emigrate to the ocean, net pens expose the smolts to pathogens and parasites at the life stage when they are most vulnerable.
Aquatic pathogens can regulate fish populations via host mortality and reduced fecundity, particularly when pathogen transfer rates are high, as among farmed/captive fish populations. Parasitized fish are more vulnerable to predation due to behavioral changes or decreased fitness.
Recent detections of particular piscine viruses in farmed Atlantic salmon from the Pacific Northwest (including B.C. and Puget Sound) highlight the risk of pathogen transfer to wild salmon via the open water net pens currently used in salmon aquaculture. Fish with poor nutrition or increased stress (as in aquaculture settings) are more vulnerable to disease. Pathogens from net pen salmon aquaculture facilities may impact native salmon populations in three ways 1) introduction of exotic pathogens from non-native fish; 2) amplification of pathogens due to the high density rearing conditions found in aquaculture facilities; and 3) selection for increased pathogenicity as the conditions found in net pens are conducive to the emergence of highly pathogenic strains.
While sea lice are a natural epizootic parasite of wild adult salmon, they are rare on wild juvenile migrants. Recent large-scale blooms of sea lice, however, are correlated with establishment of adult salmon farms. Increased lice loading is fatal or detrimental to wild juvenile fish, and research conducted by WFC indicates an increase in the infection rate of wild juveniles observed in the proximity of Atlantic salmon net pens. Further research is needed to determine if population-level effects are occurring.
WFC is in the process of conducting piscine virus surveillance in Puget Sound.
Here are some of the papers, reports, articles and videos we feel are important to gain a better understanding of salmon aquaculture and it's potential impacts to Puget Sound.
- Wild Fish Conservancy sues federal agencies for allowing harmful Atlantic salmon net pens in Puget Sound - November 4, 2015
- Fish farms could prompt lawsuit against government - King 5 News report, Aug 26, 2015
- Environmental Protection Agency & National Marine Fisheries Service Violating Endangered Species Act - Aug 25, 2015
- Salmon Confidential - Documentary film unravels the mysteries of BC’s declining salmon stocks produced by Twyla Roscovich and Salmon are Sacred, March 2013.
- Cohen Commission Press Release - Canadian Salmon Inquiry Exposes Agency Conflicts; US Needs Similar Effort, November 2, 2012.
- Going Viral: A Major IHNV Outbreak in Puget Sound - WFC report for Wild Fish Runs e News, June 13, 2012.
- ISA Virus Update - April 16, 2012.
- Scientific report says sea lice has spread to British Columbia's most lucrative fish stock distributed by Huff Strategy (ECO), March 31, 2008.
- A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids by Jennifer S. Ford and Ransom A. Myers published in PLoS Biology, February 2008.
- The Sea Lice are Spreading. Is the Government Noticing? by Stephen Hume published in the Vancouver Sun, January 23rd, 2008.
- Panel Discussion on Fish Farms and Wild Salmon with host Charles Boylan broadcast live on CFRO co-op radio on January 23rd, 2008.
- Salmon Aquaculture in the Pacific Northwest, A Global Industry by Rosamond L. Naylor, Josh Eagle, and Whitney L. Smith.