Upstream Battle: What Is Killing Off the Fraser River's Sockeye Salmon?
Comment Activity, Scientific American, By Anne Casselman | May 5, 2011
2. grantwarkentin 04:41 PM 5/5/11
It's disappointing that Scientific American has written another article which references salmon farming without doing any scientific research on the subject.
I refer specifically to the sentence which states "Months after the study came out mid-January in Science the research continues to make waves on Canada's west coast as journalists and environmentalists speculate as to whether the genomic signature identified in the study might be evidence of an epidemic of salmon leukemia, known to plague salmon fish farms along British Columbia's coast."
First, salmon leukemia is not "known to plague salmon fish farms." The last time any farms in B.C. had a problem with salmon leukemia, also known as marine anemia or plasmacytoid leukemia, was nearly 20 years ago when B.C. salmon farms farmed almost exclusively Chinook salmon. The disease is of particular concern for Chinook salmon. Since then most farms have switched to farm mostly Atlantic salmon, and all are continually improving farming practices. Since the early 1990s the disease has not been a problem for B.C. salmon farms which farm Atlantic as well as Chinook salmon.
Second, scientific research from the late 1980s suggests the disease was not new, merely newly identified. In fact, an identical disease was identified in 1974 (before there were salmon farms in B.C.) in freshwater Chinook smolts in a Washington State hatchery, suggesting it is present before saltwater entry.
Third, farms test regularly for marine anemia and have reported to the province if any cases have been found. From 2003-2009, only three cases were found.
Finally, I found it surprising that the article gives no mention to the billions of hatchery-raised fish from Alaska, many of which carry disease, which share the same North Pacific ocean feeding grounds every year with Fraser River sockeye. Competition for food and other negative interactions between B.C. and Alaskan fish must be considered in the discussion about what is happening to Fraser River sockeye.
3. Anne Casselman 05:58 PM 5/5/11
Dear Grant, Really briefly, I would argue that the sentences that you quote of mine are indeed accurate, although I can appreciate that given the controversial nature of this topic, perhaps they can be construed as misleading.
It is certainly true that the Kristi's study has led journalists and environmentalists to speculate about whether the genomic signature might be evidence of an epidemic of salmon leukemia. I think the key word here is "speculation". In fact, any inferences from Kristi's science paper are all speculation, which I think my article, and the study authors I quote make quite clear. Her study raises many more questions than it answers. As I write in the article, the scientists have yet to identify the viral pathogen so there's no saying that it's salmon leukemia in the first place. Nor, as I write, is there any causal evidence linking the signature to mortality. It's simply correlation.
As for salmon leukemia plaguing fish farms, it is certainly true that epidemics swept through feedlots in the early 90s. And I am sure that the industry has done its best to mitigate such risks, as would be in their own best interests no doubt! In the vein of clarifying my statement that "known to plague fish farms" I suggest that we change that to "known to have plagued fish farms".
As for the final issue of the competition with Alaskan hatchery fish, none of the six renown fisheries biologists I interviewed for the piece mentioned this issue. Infection from sea lice from the fish farms is also a commonly espoused hypothesis for explaining the shrinking numbers of spawning sockeye but I didn't mention that hot-button topic because none of the experts I interviewed mentioned it as leading hypothesis, in their opinion.
Grant, I must tell you that the point of this article is not to point the finger at fish farms. In fact, it's not about farmed salmon at all. Indeed, the point of the article is that anthropogenic stressors (such as pollution and climate change) are acting in concert with a mystery pathogen to prevent the sockeye from successfully spawning, and as a result their populations may be dwindling.
If you see me gunning for your industry in this piece then you are entirely mistaken, and I am sorry that you construed the piece in such a manner.
4. grantwarkentin 07:00 PM 5/5/11
Thank you for making the change to the past tense "plagued." And again, this disease has not been a problem in the industry since the early 1990s, and the industry has come a long way since then.
I understand that your article was not about salmon farming, and other than the paragraph I mentioned, I found it quite excellent and informative. But given that there is a large and concerted effort on the part of some activists to make the Cohen Commission all about salmon farming, I also hope you can appreciate how seriously our industry takes any speculation linking salmon farms to diseases which may or may not exist, and which may or may not be killing massive amounts of wild salmon.
Our industry has provided more than a decade's worth of data to the Cohen Commission because we have nothing to hide, and are confident that salmon farms did not cause the decline in Fraser River sockeye returns. Despite all our openness, it is disheartening that speculation runs rampant about our operations when all people need to do is ask, or come see for themselves.
Also the question of interactions between hatchery and wild fish has been hotly debated for years: http://www.stateofthesalmon.org/marinecarryingcapacity/
Also, here is a very thorough study done by Japanese scientists, who have also noticed sockeye declines in Japan since the early 1990s similar to what is happening on the Fraser River: http://www.npafc.org/new/publications/Bulletin/Bulletin%20No.%205/NPAFC_Bull_5_293-302(Kaeriyama).pdf
They state that "biological interaction between wild and hatchery populations is an important issue in the sustainable management of Pacific salmon production at the ecosystem level."
Correlation does not equal causation, but the early 1990s was the same time there was a massive increase in hatchery production of salmon in Alaska. See Figure 8 in the study, as well as the preceding table, for detailed numbers. I certainly would like to see more science done on this issue, given that many fisheries scientists believe that all Pacific salmon go to the same feeding grounds in the North Pacific. What happens there, affects them all.
I see you use the term "feedlot" to describe salmon farms. Again, I invite you and anyone else to see for yourself that this term, chosen by anti-salmon farming activists to paint a negative word picture of salmon farms being like cattle feedlots, is inaccurate. In our net pens, the fish only take up three per cent of the pen volume. The rest is water.
