Sea lice study adds to manufactured body of evidence

The following is a guest post by reader Bob Milne, who is writing in response to a study published in November 2012. Thanks Bob, for submitting this and for allowing us to share it, with a few silly pictures inserted. (PS – read this if you are unclear on why the XKCD cartoon is funny.)

by Bob Milne

Many people believe farm-origin sea-lice are to blame for reduced wild salmon stocks in several salmon farming areas of the world.

This belief is based on numerous articles, primarily in the media, which have selected only certain aspects of on-going research and sensationalized the somewhat dubious results. This article looks at one instance of this manipulation of the data and facts relating to the fish farms of Ireland and Norway. It is shown that the research cannot draw any conclusions about wild fish, since no wild fish were used in the study.

It is important to understand that relatively little is known about the reproductive cycles of the species of louse at the heart of the issue.(Lepeophtheirus salmonis). So let’s focus on what we do know.

Sea lice
Yet another sea louse study makes bold claims that the data doesn’t bear out.

In order to take a hard look at what is really known we must ignore the media and focus attention on the research papers and the scientific reviews they quote and compare them to the accompanying press releases, conclusions, and recommendations. This comparison will illustrate just how highly politicised the issue is. All press releases and media pieces are only telling part of the story, commonly omitting inconvenient truths that spoil the story line. Public opinion is thus formed by how the data is interpreted and which conclusions are drawn rather than by the methodology or data found within the study. The scientific method and data alone should allow the reader to draw their own conclusions, if indeed any may be made.Research money is scarce unless there is a cause supported by the public and grant donors that seems to have some urgency. Today the popular topic is: “farm origin sea-lice killing wild salmon.” There have been many research papers and reviews condemning the salmon farming industry of late. Every week seems to bring more press releases and alarming headlines quoting these papers from Canada to New Zealand, Scotland, Norway and Ireland. One would gather from the media that farm origin sea-lice are polishing off all the wild salmon in the world. But when you hunt down the quoted research papers and reviews of the scientific literature and their references, there is a much different story to be told.

Let’s take the recent review and press release from the prestigious St. Andrews University as case in hand. The research paper published Nov. 7 2012 can be found here.

The lead author is the same anti-fish farming activist ( Dr. Martin Krkosek) who has drawn his conclusion about sea-lice as far back as 2004 and has been successfully searching hypotheses and funding ever since. And since the conclusion has already been found (salmon farms are bad) there is endless hypotheses and funding flowing to the activist hero scientists of our day.

The paper is a meta-analysis of the data from six very different studies done in Ireland on fish returning 2002-6 and in Norway on fish returning between 1996-8. One of the many things Dr. Krkosek doesn’t talk about nor mention in the press release is that all of the fish involved in his review are hatchery origin fish bred for over 30 years for ranching purposes. They have been cultured for at least a year in fresh water then approximately 50 per cent of the subject fish were treated with proven anti sea-lice treatment of either emamectin benzoate or, Substance Ex (Alpharma) which involves a topical bath treatment previous to release .They were for the most part released in large numbers although at various times but nevertheless very little can be inferred (if anything) towards wild fish from this data.

Upon close inspection of the data used for the study one will notice that over 63% of the 283,347 fish released (181,271) were part of a detailed study in Ireland.

The lead author is D. Jackson from the Marine Institute, Rinville, Oranmore, County Galway, Ireland. His conclusion is very different from that of Dr, Krkosek, as exemplified in the following quote. From the paper titled  “An evaluation of the impact of early infestation with the salmon louse Lepeophtheirus salmonis on the subsequent survival of outwardly migrating Atlantic salmon, Salmo salar L., smolts:”

The results to date show a strong and significant trend in increasing marine mortality of Atlantic salmon originating in the study area. They would also point to infestation of outwardly migrating salmon smolts with the salmon louse (L. salmonis) as being a minor and irregular component of marine mortality in the stocks studied and not being implicated in the observed decline in survival rate. (Jackson et al, 2012)

There are two very important distinctions between the analysis in Jackson’s original study and the meta-analysis of the same data by Dr. Krkosek et al.

Firstly, the work of Jackson is objective. Because the source for the theoretical sea-lice of unknown species is indeed unknown, the source is responsibly not mentioned.

Secondly, considering the subject fish are all hatchery raised ranch fish and have been bred as such for at least 30 years, Mr. Jackson makes no reference to wild fish in the paper. The research has absolutely nothing to do with wild fish or farm fish so in the name of good science, it also requires no mention.

In contrast, the Krkosek paper contains the word “wild” eleven times and salmon farm/aquaculture no less than fourteen times, despite his meta-analysis having absolutely nothing to do with wild or farmed fish. For example, a quote from the recent St Andrews press release leads one to believe that there have been clinical studies on wild salmon when the research in fact had no clinical studies and was not done on wild salmon. No new data was brought forth.

“Our research is similar to clinical studies in medicine – except that wild fish are the patients.”
­— Professor Martin Krkosek

In addition, the most important discovery in the Jackson trials is the strong and significant trend in increasing marine mortality of the hatchery Atlantic salmon originating in the study area regardless of whether or not they have been treated for sea lice, as illustrated in the graph below. This graph represents over 63% (181,211 fish) of the data used by Dr. Krkosek for his review yet displays approx. 1.5% higher mortality in the untreated fish as opposed to the 39% claim we see in the headlines.

Survival of salmon in Irish sea lice study. Sea lice appear to have played little if any role in the declining survival trend.

This trend is significant because it shows clearly that although the treated fish exhibit slightly higher returns, (as we would expect) the increasing mortality rate over the years is identical (parallel lines).

So it follows that if farm-origin sea-lice were to blame for increased mortality of wild/hatchery fish we would see a corresponding increase in survival of the treated fish in relation to the untreated fish throughout the study period (diverging lines) or at least notable disparity between the two lines on the graph above in relation to lice loads at the salmon farms. This notable trend strongly suggests no effect of farm-origin lice on the mortality of ranch/wild fish in the area but as this trend contradicts the story line of Dr Krkosek’s paper; it is not mentioned.

Dozens of Published articles by Dr. Krkosek on sea-lice and disease all draw the same conclusion from his mathematical models. Many are simply re-hashing of old data by reviewing it and coming to the same conclusion (salmon farming is bad), without any conclusive evidence. The names appearing as co-authors are a virtual who’s who of salmon-farm hating activists posing as impartial scientists to line their pockets and further their anti- farm agenda.

It is not an accident that we get alarmist headlines like “salmon farms kill 39% of wild salmon” or “massive extinctions of pink salmon from fish farm sea-lice” that quote papers by Dr. Krkosek and his ilk. There are thousands of media outlets and blogs dedicated to the purpose. The press release from St. Andrews mentions wild fish 3 times and salmon farms twice. They quite craftily wrote it up that way in the press release, knowing journalists and editors readily omit the cans, coulds, mights, and maybes.

The fact is there is no known mechanism for determining the origin of a sea louse nor to distinguish farm-origin from naturally occurring animals and very little is known about background levels of the copepods that infect the farm fish or the wild/ hatchery fish in the first place.

The modelling that Krkosek and his colleagues use is only one tool in an arsenal that should be used to further our understanding of sea-lice /salmon interactions, but instead is being used as a weapon to unjustly condemn the salmon farming industry.

The topic requires a detailed understanding of the complicated host-parasite relationship at hand. The model is taken from epidemiology and crudely tweaked to apply to sea-lice transmission dynamics. From a rational perspective one can’t help but think that if this modelling did not indicate that the sky is falling then it would serve no purpose at all. Thus it follows that the mathematical models will continue to condemn salmon farming for the foreseeable future as long as the inputs to the model and the press releases are controlled by the same activists, scientists, and researchers.

A quote from the innovative neuroscientist ‘Ramachandran’ famous for his simple yet elegant science on brain plasticity:

“I have a disdain for complicated fancy equipment because it takes a lot of time to learn how to use, and I’m suspicious when the distance between the raw data and the final conclusion is too long. It gives you plenty of opportunity to massage that data, and human beings are notoriously susceptible to self-deception, whether scientists or not.”
— Ramachandran

Here is one of many criticisms from respected federal fisheries scientists Brian E. Riddell et Canada regarding Krkosek’s extinction predictions from a 2007 paper titled “Declining Wild Salmon Populations in Relation to Parasites from Farm Salmon:”

Krkosek et al. overstated the risks to wild pink salmon from sea lice and salmon farming.
Furthermore, their predictions are inconsistent with recent observations of pink salmon returns to the Broughton Archipelago. Their alarming statements of extinction of pink salmon in the BA are only possible with highly selective use of the available data and extrapolation of their results to all pink salmon in the BA. In assessing and managing pink salmon in the BA, all potential impacts on the productivity of these pink populations, including sea lice, should be acknowledged in developing an effective management strategy.

And here is Dr. Krkosek’s response.

The response by Krkosek et al is such a confusing, technical, and complicated response (much like the original paper) that it loses most readers within a paragraph, leaving only a handful of expert mathematicians that could actually understand and comment. The rest of us will be baffled by the complexity and bewildered by the fact that the response doesn’t address any part of the well-articulated criticism. It is a clear attempt to obfuscate the issues and hide behind jargon and complexity.

Considering Dr. Krkosek wrongly predicted the extinction of the Pink Salmon in the Broughton Archipelago in British Columbia and consistently comes to the same gloomy conclusion all over the world with his models and statistics what are the chances of such biased researchers ever finding a true causal relationship? Zero.

Because salmon farms are already convicted in the court of public opinion without a shred of evidence.

Court of Public Opinion

Not surprisingly, this study was used to write numerous flawed anti-salmon farming articles. Here are some samples of how it was used as “weapons-grade junk science.

Reaction to a planned salmon farm in Ireland:

Concerns about the potential impact of the farm have intensified following the recent publication of an international study by the Royal Society of Biological Sciences, which found that on average 39 out of 100 wild salmon are killed by sea lice.


Research has shown that 39 per cent of wild salmon mortalities are attributable to sea lice,” said Dep Grealish.

And finally:

Research has shown that infestations of sea lice concentrate in salmon farms and this can pose a serious threat to wild salmon and sea trout during their migration period.

Upon review of the data in the study, all these claims are, in fact, completely wrong.


3 thoughts on “Sea lice study adds to manufactured body of evidence”

  1. Thanks for that Phil. Would it be a bad idea to publicly demand that Krkosek et Al. release all the raw data and inputs to the black box model used in the meta-analysis? I read somewhere that extraordinary claims require extraordinary evidence


  2. Nice write-up by Bob Milne. I always enjoy reading his well reasoned comments among the sea of regurgitated vitriol that follows many of the east coast ‘news’ stories surrounding salmon farming. But seriously guys, maybe give it a rest with the cartoons and bad memes in every post. Leave the childish captioning and bad photoshoping to Don Staniford and his cronies.

  3. Bob Milne’s analysis whist well founded misses out several points of ‘misdirection’ arising from the paper and more importantly the related press release. Points to note are:

    1. In one case three of the studies undertaken by Jackson have been pooled to give an aggregate value in the data used for meta analysis. What kind of meta analysis is this?

    2. The 39% figure derives from the computation of phi in their log model not the arithmetic mean. It is their estimate of loss of salmon recruitment. i.e. if recruitment is 5% and it reduces to 3.05% then their measure of loss of recruitment is 39%.

    3. However, the News release, the later statements by St Andrews University, and the (uncorrected) interpretation of the press coverage was that 39% of salmon in Atlantic are killed by sea lice.

    Go figure!

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