Sea lice science ain’t done yet

I don’t work on sea lice any more because I figured it out. Where there’s fish farms, there’s sea lice. It’s an extremely easy thing to study, way easier than whales.

— Alexandra Morton, author and co-author of numerous sea lice studies, speaking at the Cohen Commission, Sept. 7, 2011

The science is never done, even if some people think they’ve “figured it out.” And it’s a good thing researchers haven’t given up on researching sea lice in B.C. because we apparently still have an awful lot still to learn.

Six UBC scientists have just published an interesting paper titled “Physiological consequences of the salmon louse (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha): implications for wild salmon ecology and management, and for salmon aquaculture.” It was published by the Philosophical Proceedings of the Royal Society B and is available to read online (we will be adding the PDF version to our library at a later date).

There is a lot of interesting information in this study, which looked at the real-world physiological effects of sea lice infestation on wild salmon.

For years, critics of salmon farms have claimed that sea lice from salmon farms are killing wild salmon. However, there has never been any evidence to support this claim, only sketchy predictions from mathematical modelling studies.

No one denies that salmon farms can increase the number of sea lice in an area; when wild fish pass salmon farms, the lice, a natural parasite found in the Pacific Ocean, can infest farmed salmon, which can act as a breeding ground for lice if not managed properly.

But what is up for debate is this: IF lice from farms infest tiny pink salmon passing by in the spring months, when they head out to sea, do they have any effect on wild salmon survival?

This new study basically says, “maybe, maybe not.”

But while this is inconclusive, this study makes several interesting new discoveries, and puts old information in a new light.


It’s well-known that juvenile pink salmon can shed sea lice, dependent on a wide variety of factors in the ocean as well as their own physiology.  But this new study makes the interesting point that previous mathematical modelling studies, particularly the well-known and well-publicized 2006 sea lice study by Morton, Krkosek et al, are seriously flawed when they do not consider shedding rates.

A high rate of louse shedding is also of importance in mathematical models, where the incorporation of realistic shedding rates [67] reduces the predicted mortality of pink salmon owing to salmon louse infection by 95% relative to an earlier model where shedding was not considered [10]. Collectively, these findings of high rates of shedding of attached lice suggest that the majority of the salmon lice that successfully infect a fish will be shed before they reach motile and reproductive stages. Clearly, the interactions between salmon lice, juvenile pink salmon and their environment are extremely complex and change temporally as both salmon louse and fish develop and the implications of this need to be considered in relation to conservation efforts.


What is ionoregulation? It’s a self-regulatory process in a salmon’s body which, if it is out of balance, can kill a salmon within days or leave survivors severely crippled. Researchers in this new study decided to see if sea lice can affect this process when pink salmon are at their most vulnerable, right after they enter saltwater. The research found that sea lice can cause an imbalance, but only until the fish are about 0.5 grams, and the implications to their survival is unclear. As well, once the salmon reach 0.7 grams, they have sufficiently increased their ability to resist and shed sea lice.


Sea lice from salmon farms may harm wild salmon, but it’s not certain. The effects of sea lice on tiny wild salmon will certainly have some effect on them at some point, so to reduce any risks, the study recommends that salmon farmers and their managers continue doing what they are doing: voluntarily fallowing farms during outmigration periods to keep sea lice levels low. This is sound advice, and a good use of the precautionary principle.

In a recent study to investigate the benefit of fallowing fish farms in the Broughton Archipelago, it was determined that fallowing reduces salmon louse levels around the farm and reduces juvenile pink infection levels to background levels [70], indicating that this recommendation and voluntary compliance may mitigate salmon louse effects on the most sensitive stages of pink salmon.

The study closes with a very interesting footnote, which leaves us with the suggestion that in the grand scheme of things, sea lice really aren’t that big of a deal for salmon. The study’s closing paragraph is a perfect way to close this blog post:

Perhaps the only study that has truly considered the impact of salmon louse infection on juvenile salmon is the 10-year study of the return of Atlantic salmon smolts that had been treated with SLICE (emamectin benzoate) to protect them from salmon louse infection for the first 90 days of their outward migration, a period which easily extended beyond the contact with net-pen aquaculture and associated salmon lice. Remarkably, a comparison with non-treated fish revealed that protection of juveniles from salmon louse infection represented a minor component to overall marine survival. Indeed, during the 10-year study, adult Atlantic salmon returns fell a similar 10-fold in both treated and non-treated fish [71]. A similar study on juvenile pink salmon treated with SLICE in the Broughton Archipelago could be very revealing in assessing the true impact of sea lice on pink salmon fitness.

We agree. This study should be done, because the science is never truly finished.


13 thoughts on “Sea lice science ain’t done yet”

  1. So you are saying that scientific work is contracted out based only on the credentials of those bidding the job?

    OK here is a question, would your salmon farming industry in BC award a contract to Morton for work around the pens?

  2. The difference is that I am looking at the nuts and bolts of her work (i.e. the recent HSMI fiasco) while some antis seem to be only focused on corruption theories. Now those theories make for great entertainment, but it’s all rhetoric with no factual basis. As this site has already said, Ms Morton has made some contributions to this issue, but is making conclusions which are not factual. In addition, she is not representing the true testimony of people like Dr. Farrell or Dr. Miller.

    1. This conversation started out discussing the sea lice paper. I am trying to point out that the author’s association with the industry will be reflect in the final outcome of any report.

      There is one golden rule I have learned in the private consulting business over the past 40 years, don’t bite the hand that feeds you!

      Bottom line, all contract decisions are made by an individual/group complete with all their prejudices. That is unchangeable human nature and for this author there is a tomorrow.

      1. We disagree. Scientists and private consultants are different and this is not a useful comparison. Scientists make or break their reputation based on what they publish, publicly. If their work is dismissed by the scientific community as biased or junk, it doesn’t really matter who paid for it. Again, if it is accepted as useful and as an important contribution to scientific knowledge, it doesn’t matter who paid for it. All scientists have biases, and the peer review process is designed to minimize and eliminate them from tainting the papers which eventually get published. It’s not a perfect process, but it’s a rare scientist who will take money from a controversial source, publish a boot-licking paper and not get called on it.

        Also, back to the study you mentioned, it was a study about stress and recovery during commercial fish transport. It makes perfect sense that a company like Marine Harvest would help fund it, because they want to know more about this issue so they can improve their transportation methods. There is nothing controversial about this. The study we based this post on was all about sea lice, and was funded by a federal government science grant program. Again, nothing controversial about that linkage.

  3. “Secondly, you might remember that antis called Dr. Miller “Scientist of the Year” during her testimony last year at the Cohen Inquiry. So, basically if she says what you want to hear she and her co-authors (Farrell) are alright? Again, if that’s true, that is pretty sad.”

    Is this not exactly what you are doing with information coming from the other side of this discussion (Morton)?????????

  4. It’s not about any study and you know it. It’s about who is doing the funding now & in the future. A negative study re sea lice would lock him out of future funding from the industry wouldn’t it?

    It’s all about the $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

    At one time we could look to DFO for the truth. Publicly funded research free of private sector strings.

    Because of politics,on the aquaculture file, they have been totally corrupted/compromised and in a massive conflict of interest.

    1. Mike, we do understand what you are trying to say and we do share the same concerns about funding money influencing the quality of science. It is a valid concern and we agree with you that it should be mentioned.

      But it’s far too simplistic to suggest that it’s all about the money.

      Maybe we’re being naive, but we honestly believe that the quality of science will stand the test of time, regardless of who pays for it. Many great scientific discoveries have been funded by controversial sources.

      We would also like to make it clear that on this site we do not dismiss science simply if Alexandra Morton is involved. She has done a lot of valuable research which has led to important discoveries and scientific understanding of sea lice.

      Where we take issue is when that science is used to draw flawed and baseless conclusions.

      The data she has helped collect has been invaluable. But the mathematical models used to process that data have spit out many flawed and wrong conclusions. Marty Krkosek, who has worked with her on many studies, has revised his mathematical models several times since they started working together nearly 10 years ago. Back in 2006, he stated that sea lice from salmon farms were definitively causing a decline in wild salmon. In his most recent study, he has changed his language quite a bit. Now, he states that sea lice from salmon farms MAY cause declines and that “management and policy of salmon farms should consider protecting wild juvenile salmon from exposure to sea lice.

      There’s no denying that salmon farms can increase sea lice in an area, and farmers acknowledge that. That’s why they time production cycles and use lice treatments during the spring out-migration period to make sure lice levels on farms are as low as possible. And for many farms, this is the only time they ever receive sea lice treatments, and only specifically to protect the juvenile wild salmon swimming by.

      This change in practice is largely thanks to the science spearheaded by Alexandra Morton, and she deserves credit for that.

      But the scientific data and body of sea lice science she has helped collect does not support the conclusion that wild salmon are doomed unless salmon farms go away. That is a baseless emotional argument which is not backed up by facts. That is what we take issue with, not the science being used erroneously to support that argument.

  5. Anthony (Tony) P. Farrell Lab
    You +1’d this publicly. Undo
    31 Mar 2010 – Stress and recovery during commercial fish transport: Commercially farmed salmon must be transported live from freshwater hatcheries to the …

    paid for by

    a Nordland Research Institute, N-8049 Bodø, Norway
    b Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway
    c University of British Columbia, West Vancouver, 4160 Marine Drive, Canada V7V 1N6
    d Marine Harvest Norway AS, Pirterminalen, N-7488 Trondheim, Norway

    Dr Miller: employer DFO

    Where are the independant/non funded voice we should listen to?

    1. What’s your point? The study you quote is completely unrelated to the study we talk about in this post, which was made possible by a grant from the Natural Sciences and Engineering Research Council. Financial contributions are often declared in science papers as they are in this one. Science is not free and most research relies on grants. If you are going to dismiss science based on who funded it you won’t have much left. Good science stands up to scrutiny and results can be reproduced and verified. it doesn’t matter who funded the science if the work is good.

    2. So, fish farm companies should not be allowed to provide funding for research that is directly related to the fish they raise? I would be surprised if they were not involved financially due to the fact that science cost money. Mike, this work is not cheap. Other than NSERC, money for this type of work has to come from industry, ENGOs, or other funding sources (i.e. Southern Endowment Fund from the PSC). It sure isn’t going to be coming from taxpayers. If the fish farm industry do fund research it should be instantly dismissed as not being “independant”? Is that what you are saying? I suggest that you are not reading the actual report or scurtinizing the content – instead you are looking at the Acknowledgement Section and instantly dismissing the report because of who is involved. That’s worse than who is funding the project because you instantly have a prejudice with no foundation for that criticism other than names.

      Secondly, you might remember that antis called Dr. Miller “Scientist of the Year” during her testimony last year at the Cohen Inquiry. So, basically if she says what you want to hear she and her co-authors (Farrell) are alright? Again, if that’s true, that is pretty sad.

  6. Probably one of the best reports I have seen on sea lice interactions with wild salmon in a long while. It doesn’t come out and say, “Hurray for salmon farms!”…Instead it attempts to take a more objective view of the issue and show the public the drawbacks for correlative work – something that is severely lacking in Ms Morton’s studies. If people are not familiar with Tony Farrell he was co-author with Dr. Kristi Miller in her paper that created quite a stir at the Cohen Commission last year. So, if anti fish farm folks are attempting to call him biased due to this lastest report then it calls into question their objectivity on this issue.

  7. Excellent post with a ton of information. Whenever I see Tony Farrell mentioned I take notice. One bright dude.

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