Another lousy sea lice study
FishfarmingXpert, Odd Grydeland, Feb. 14, 2011
Canada: With great fanfare, a group of anti-salmon farming “scientists” throw out a bunch of numbers and interpret them to suggest that the sky is falling on the wild salmon in British Columbia. And as usual, the numbers don’t back up their claims
The California based Public Library of Science is the publisher of the journal PLoS ONE, which earlier this month issued a “peer-reviewed” report about sea lice and sockeye salmon in British Columbia; “Price MHH, Proboszcz SL, Routledge RD, Gottesfeld AS, Orr C, et al. (2011) Sea Louse Infection of Juvenile Sockeye Salmon in Relation to Marine Salmon Farms on Canada's West Coast”. Regular observers of issues surrounding salmon farming and wild salmon in this part of the world will recognize the names of most of the authors as people actively engaged with the campaign to remove salmon farms from the coast of B.C., and the same goes for the long list of American foundations that paid for the study.
The otherwise respected PloS ONE journal boasts of- among else- “Fast publication times” and “Worldwide media coverage”- just what the doctor ordered. And according to its web site, “Academic Editors work together to orchestrate the peer-review process and are responsible for making decisions on which manuscripts should be published in PLoS ONE”. From my search among the hundreds of names in the list of Academic Editors from all over the world, I only found four from universities in British Columbia- a brain researcher (Brian Christie- University of Victoria), and three scientists from the University of British Columbia- one an expert on the effects of the promotion of human drugs (Barbara Mintzes), an expert on the genetic exchange systems in bacteria (Rosemary Redfield) and a specialist in hypertension (James Wright- Professor, Departments of Anesthesiology, Pharmacology & Therapeutics and Medicine). None of these excellent researchers seem to have a background in fish or fish parasite research.
It is puzzling to say the least that a publication like this can make it through any form of “peer-review” process. The main conclusion of the study- which supposedly looked at the amount of sea lice on sockeye salmon before and after they passed by salmon farms in the Strait of Georgia (the body of water between Vancouver Island and the B.C. mainland) and the north coast of the Province- where there are no salmon farms- was that “New research shows sea lice from salmon farms infect Fraser River sockeye”, and “Juvenile sockeye migrating along the north coast hosted an order of magnitude fewer sea lice than those migrating through the Discovery Islands”.
The one good thing about this study was the classification and genetic identification of a few hundred sockeye salmon smolts found in different locations of the B.C. coast, but the benefits end there.
First of all- there are no salmon farms in the Strait of Georgia. Secondly- there was no information in the study about the actual presence/absence of sea lice on the farms in the study area, which actually was the southern portion of Johnstone Strait/ Okisollo Channel, Cordero and Nodales Channels. Thirdly- there was no mention about the fact that the most commonly found species of the sea lice found on the sockeye salmon has seldom been associated with damage or disease of salmon- certainly not at the low average levels reported in this study.
And the authors only make a brief mention (“though brief localized outbreaks have occurred”)of a recent study from the Strait of Georgia that documented an “outbreak” of this very species of sea lice on sockeye salmon far away from any salmon farms. When the authors found a population “upstream” of salmon farms that had higher levels of sea lice than samples taken ‘downstream”- these numbers were isolated from the rest, and called an “outlier” series of numbers.
Anybody involved with sea lice research in B.C. (and elsewhere) know that sea lice levels are routinely associated with salinity. The authors of this study speculate that “Factors beyond the absence of farm salmon on the north coast may have contributed to the significantly lower lice levels on sockeye compared to the Discovery Islands. In particular, differences in lice levels may be due to our use of different sampling gear or different environmental conditions, though we did incorporate the two key conditions known to affect sea louse infection levels into our analyses: salinity and temperature. Our analyses show that the lower infection rates for C. clemensi on the north coast cannot be explained by salinity and temperature alone. The primary strength of our study was the comparison of infection levels before and after fish had been exposed to salmon farms within the Discovery Islands”.
The problem with this is that if you look at salinity alone, you’ll see that the average salinity in the area sampled in the north coast was less than 17‰, while ocean salinities from sampling around the salmon farm all exceeded an average of 25‰- a significant difference. And the sockeye salmon sampled “downstream” from salmon farms were much bigger (~30% and ~48% respectively) than those sampled “upstream” from farms- suggesting that they would have had more time to accumulate the few extra lice that were found on these fish.
Publisert: 14.02.11
