Science News & Commentary
December 13, 2010 – New study suggesting sea lice not to blame for harming wild salmon is inconclusive and fails to convince when weighed against the full scope of science on this subject
A new paper claims that sea lice from salmon farms are not harming wild fish. While the authors confirm salmon farms are the main source of lice on juvenile salmon, their primary conclusion—that productivity of wild salmon is not negatively associated with either farm derived sea lice or farm fish production—is in stark contrast to many published studies linking farming and lice to declines in pink and coho salmon, sea trout, and wild Atlantic salmon.
Academic scientists have already raised concerns about the methods used to analyze data in the new study. Looking at trends in wild adult salmon returns has been criticized for not taking into account different geographical factors, different times of the year and other variables. The authors claim sea lice from farms are not a significant factor driving the decline of pink salmon in the Broughton Archipelago, but fail to name the missing link, and offer anecdotal observations that sea lice may be a valuable food source for juvenile salmon. The report also fails to consider the potential of sea lice as vectors for disease transmission with associated lethal or sub-lethal effects from farmed to wild fish.
Because different hypotheses and methods of data analysis can yield different results an analysis of the raw data by independent scientists (currently underway) is required. It is worth noting that independent researchers in BC who have been studying this issue for years were never given access to the on-farm data used in this study.
Salmon farming has myriad negative impacts on wild fish and ecosystems and CAAR believes, as do most scientists who publish on lice impacts, that the evidence of such impacts remains solid. This new study does not provide conclusive evidence to circumvent the precautionary principle therefore a transition to closed containment technology for salmon aquaculture remains the valid path.
With reference to the study by Gary Marty, Sonja Saksida and Terrence Quinn entitled ‘Relationship of farm salmon, sea lice, and wild salmon populations.’
May 19, 2009 – New paper from Dr. Martin Krkosek, Alexandra Morton, Dr. John Volpe and Dr. Mark Lewis examines the process of sea louse transfer to wild juvenile salmon.
The authors specifically looked at the period of time the salmon were exposed to infective stages of lice and the importance of the exposure period with regards to interpreting experimental field results and lab results.
In the past, Fisheries and Oceans Canada (DFO) has published work that reported juvenile salmon exhibited low levels of attached mature louse stages by observing experiments conducted in the lab. They also report low salmon death rates from these experiments; however, these lab results don’t mesh well with the field sampling studies that have been published which report high levels of sea louse infection on wild juvenile salmon and projections of population collapse. How can this be?
The lab studies show that many of the lice don’t attach to juvenile salmon and die, but if this is the case then why do the field sampling studies show a high prevalence of lice on the fish and predict local extinctions? One of the main conclusions Krkosek and company come up with is that fish exposure time to lice is important. The lab studies conducted by Fisheries and Oceans Canada only expose fish to infective stages of lice for hours. However, in real life (as more accurately described by the field sampling studies) the wild salmon in the Broughton Archipelago are exposed to lice for weeks and sometimes months. It turns out hours vs. months makes a big difference (of 2 to 3 orders of magnitude).
Put another way, think about the chances of catching the swine flu. You may be able to get away with being in closed quarters with infected people for 2 hours, but what about 2 weeks? In summary, studies by DFO suggest rosy results from lab studies conducted under short exposure times; however, the exposure time they used isn’t comparable to what is happening out in the ocean. Therefore, their results may be greatly underestimating the problems posed by sea lice from salmon farms.
March 23, 2009 – Fraser River Sockeye May Be At Risk of Sea Lice Infection From Salmon Farms
Genetic analyses have confirmed the predominance of Fraser River populations in samples of juvenile sockeye salmon caught near salmon farms in northern Georgia Strait. Preliminary laboratory results identified 30 Fraser River stocks (sub-populations), with dominant stocks in 2007 from Chilko and Quesnel Lake, and in 2008 from Chilko and Shuswap. Approximately 60% of the sockeye sampled in 2007 and 99% in 2008 were from the Fraser River.
February, 2009 – BC Pacific Salmon Forum releases it’s final report after three years of government supported research mandated to create better policies to protect wild salmon and manage aquaculture.
The report frankly acknowledges the magnitude of the problems created by open net-cage salmon farms, calls for better environmental protection, and recommends that the Provincial government get on with funding a commercial-scale closed containment project. However, the report also makes several recommendations that suggests continuing current practices despite known impacts to wild salmon. Read more on the PSF.
January 2009 – Dr. Neil Frazer, Professor at the Department of Geology and Geophysics at the University of Hawaii, speaks to CAAR about what a deadly virus like Infectious Salmon Anemia (ISA) could mean for BC.
August 2008 – Stan Proboszcz and Dr. Craig Orr of Watershed Watch Salmon Society and the Coastal Alliance for Aquaculture Reform respond to the January 2008 report Overview of Sea Lice Issues and Risks for Farmed and Wild Salmon prepared by Saksida and Downey for Cermaq (Mainstream).
June, 2008 – A new sea lice map shows juvenile pink and chum salmon swimming near salmon farms suffer higher levels of sea lice infestation than juveniles in fish farm-free areas of the B.C. coast.
A new map, produced by the Living Oceans Society, compiles all the available sea lice sampling from recent years into one geographic representation. The map locates the sampling sites for each study throughout the BC coast in relation to fish farms that were active at the time of the sampling. It separates the sites into three distinct areas where wild juvenile pink and chum salmon were either exposed to, peripheral to or not exposed to active farms and displays the results in pie charts. The size of each pie is based on the size of the samples in each study. The size of each slice of pie shows the prevalence of sea lice infestation found on the wild juvenile salmon by species. “Prevalence” means the percentage of the total sample that has sea lice.
By putting all the data onto one map, it becomes clear that whereever there are active open net pen salmon farms in BC, sea lice levels on wild juvenile salmon are higher than where there are no salmon farms. Download Map (PDF) (JPEG).
March 2008 – Dr. Craig Orr of Watershed Watch Salmon Society and the Coastal Alliance for Aquaculture Reform reveal problems with the Pacific Salmon Forum report Science and Sea Lice: What do we know? prepared by Dr. Brian Harvey.
Feb 8, 2008 – BC Pacific Salmon Forum acknowledges that the recent Science study shows link between sea lice and pink salmon declines in Broughton Archipelago.
The BC Pacific Salmon Forum issued a media release after meeting with the authors of the recent peer-reviewed Science article Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon. The PSF acknowledges that the study shows a link between sea lice and pink salmon declines in the Broughton Archipelago and that the prediction of extinction will depend on future management plans.