More debate: Orjan Karlsen and Karin Boxaspen from the Institute of Marine Research have chosen to continue their discussion of sea lice science in the pages of Intrafish media rather than using the more traditional scientific forums.
They say that claims have been made that there is a great lack of knowledge about sea lice. This is the problem when such discussion take place in the media because this is not what was said. The point is that there is a wealth of sea lice knowledge which is ignored by the existing scientific clique simply because it doesn’t fit in with their narrative about sea lice.
They also say that it is claimed that the research institutions do not want to use any new knowledge and even that they don’t want to hear such knowledge. In my opinion, this is true. They are only interested in new knowledge if it supports their narrative. This is clear from a statement in their commentary that they are definitely interested in new knowledge, but they then say that any new knowledge must not be an obstacle to using knowledge that they already have.
It is interesting to then hear their response to any new knowledge, which they say is included in the Expert Group reports and is assessed on an ongoing basis. Again, they stress that it is not automatic that any new knowledge is given full consideration because it must be measured against their established narrative. Simply put, unless any new knowledge agrees with their view, it is not of any interest.
Their blinkered view on what constitutes new knowledge is apparent from their explanation of how anyone can search for this new knowledge themselves. All one has to do is type in search terms such as ‘salmon louse’, ‘sea lice, or the Latin name for sea lice into one of the databases such as ‘Web of Science’. They then give an example that IMR researchers have been involved in 128 scientific articles about sea lice since 2017 and 209 in total.
This is amazing. I would like to thank Dr’s Karlsen and Boxaspen for pointing out how to search for such new knowledge. However, as they well know, not all knowledge is published but appears in reports and other outlets. At the same time, just because research has been published, does not mean that it is valid or relevant.
A new paper that appeared recently is supposed to reinforce the message that sea lice harm wild fish populations is co-authored by those close to anti salmon farm activist Alexandra Morton including Sean Godwin, Martin Krkosek and Mark Lewis. The paper is published in the journal ‘Theoretical Ecology’ which sums up this work very well as it focusses on the use of a theoretical dynamic model.
The paper is an explosion of mathematical terms and equations, which is not my forte. However, the discussion includes a section on ‘Model Limitations’ which caught my eye. In this they say that they made several simplifying assumptions about louse biology. First, we assumed that sea lice distribute following independent, identical Poisson distributions.
Before I comment on the distribution, they then admit that whilst this assumption is mathematically convenient, sea lice tend to be more clustered in their distribution i.e. over-dispersed. Thus, they say, this might over-estimate the negative impact of lice on juvenile salmon populations.
Regular readers of reLAKSation will know that I have highlighted that parasites are distributed as an aggregated distribution. This is sometimes referred to by the confusing term ‘over-dispersed’. The problem is that the modellers and those who are not parasitologists see the distribution as a statistical expression rather than a biological life strategy. Since they don’t recognise the biology, they then decide they can make simplified assumptions which are totally inappropriate. They even accept that it may be an assumption too far, but they continue anyway and eventually publish a paper which has no value because it makes too many assumptions. Of course, this won’t stop it being prompted as another example of proof that salmon farming has a negative effect on wild fish populations.
The commentary from the IMR researchers begins by stating that research has shown that sea lice have a negative effect on wild population of salmon and sea trout in Norway. However, their claimed relationship between sea lice and wild fish stocks is too reliant on conjecture and very short on real evidence. This is exactly why the Traffic Light System has failed to protect wild salmon stocks. More stringent controls on sea lice on salmon farms has not stopped the decline despite their claim that they have the solution to protecting wild salmon in Norway. They say that the answer is to reduce the number of sea lice released from salmon farms and it is up to government to work out how to do this. Their contribution is to continue to increase knowledge about sea lice, wild and farmed salmon. Clearly contributions from anyone else are still not welcome.
It is easy to make such statements in the media but perhaps not so when face to face with a wider scientific audience. I have previously proposed that a new conference or meeting be convened to discuss these matters in a more traditional scientific format. If Drs Karlsen and Boxaspen are confident about their science, then this should not cause them any undue concern.
Rivers again: The published paper from Mari Lei Larsen linking declines in the wild salmon river catch with sea lice infestation has prompted me to explore the issue further. Dr Larsen produced a single graph summarising the change in catches from each production area, which proved difficult to decipher due to its small size.
I have obtained all the catch data from Statistics Norway, which is expressed by county. However, from 2020 to 2023, Statistics Norway extracted the data from some counties and placed it into a separate dataset. This required it be replaced into its correct place before the data could be plotted. Before considering the county data, it is worth looking at the total catch (number of fish caught) for the whole of Norway.
The graph shows that there is a clear downward trend with the latest data being the lowest on record.
However, what is very much of interest is that if the graph is plotted to 2016, which is when the Traffic Light System was introduced, the catch trend is quite stable.
I cannot say whether the change occurred because the introduction of the TLS assessments or not, but the potential link is worth further investigation. My current analysis focuses on 16 counties and regions. Each is graphically plotted and a trend line applied. As the trend line covers a timeline for 1993, it can be influenced by changes in just one part of the series. However, as all areas were treated in the same way, the following may be of interest.
Of the sixteen areas, eleven have distinct downward trend. Of the remaining 5, two show increased catches. These are Agder and Troms, which are at different ends of the country. Two others show a very slight increase (Nordaland and Sogn & Fjordane), whilst the last one, Vestland, looks relatively stable, despite catches being in decline in recent years.
I was particularly interested in the years 2012 to 2020 because catches as shown in the following table:
There is clearly some variation in the number of fish taken every year and I wondered whether there was any control on the number of fish caught in order to protect stocks. In 2013, A Quality Norm for wild salmon was adopted by Royal Decree in Norway. The norm is an assessment tool that is used to assess the status of individual salmon stock and thus influence management decisions. Part of the assessment process is to evaluate whether there is a harvest potential for each river. There are seven categories for assessment ranging from very good to very poor. The aim is that any river should be classified as good or very good. Any river classified as moderate, poor or very poor should have a management plan in place with the aim of improving the stock. My understanding is that anglers believe that this Royal Decree gives them the right to exploit Norwegian rivers. If they can’t, then they are happy to blame salmon farming for the claimed poor state of the river stocks.
To evaluate whether fishing should be allowed, the Scientific Committee for Salmon Management (VRL) assessed a range of Norwegian rivers. The last assessment was published in January 2020 in report NR 13 covering the five years ahead from 2021 to 2025.
This report provides an assessment for 232 rivers the advice for which is summarised as:
Nearly 60% of rivers are effectively unrestricted with just over 20% closed to fishing (there are 24 rivers that are unclassified).
However, the most interesting aspect of this assessment is that just 24 rivers (10%) are said to be impacted by sea lice from aquaculture. Given that VRL say that sea lice are the greatest threat to wild salmon stocks, this is most surprising. This is even more so when 11 of the 24 rivers are classified as 1 with no control on fishing. A further ten are subjected to a moderate reduction in fishing whilst a significant reduction is recommended for just three of the twenty-four rivers. Seemingly other factors appear to have a greater impact than sea lice, if sea lice have much of an impact at all.
Whilst I might have implied that the introduction of the TLS has had a negative impact on wild salmon stocks, I am reminded of the past situation in Scotland. Before 2010, the clear narrative was that sea lice had an impact on wild fish because catches from rivers near salmon farms were in decline whilst catches from rivers on the east coast, where there is no salmon farming were promoted as showing increased catches. Then in 2011, the east coast catches collapsed. From then on, the east west coast split was rarely mentioned and in fact, the reasons for the collapse have never really been discussed, simply because there was no feasible explanation.
My view has always been that the fall in the number of returning salmon was first noticed in the small spate streams of the west coast which never held a large stock of fish. This fall was and still is blamed on salmon farming. In the subsequent years, the remaining stocks managed to hold on and avoid a total collapse as some fish did continue to return. As the reservoir of fish in the much larger east coast rivers continued to provide sport, eventually the reservoir became exhausted and together with reduced numbers of returning fish, the stocks collapsed in 2011, just as they had done twenty years earlier on the west coast.
If I look at the catch trends to 2016 in the various counties already plotted, then the trends are either reserved or show less of an impact. Hordaland catches show a downward trend to 2024 but an increasing trend to 2016. It is possible that as in Scotland in 2011, the impact of reduced returning fish has had a massive impact on catches from 2016 onwards. Unfortunately, because no -one has really studied such trends, the blame naturally falls on salmon farming’s shoulders.
We also need to remember that salmon farming has been operating since the 1970s and as far as I can gather it is only in the most recent years, that catches of wild salmon have collapsed. Unfortunately, Statistics Norway data begins in 1993, and although there is data from 1876, the numbers of rivers for which catch has been recorded has increased and the catch includes both salmon and sea trout and is expressed in tonnes. This makes it almost impossible to determine any trends, but I suspect that catches were relatively healthy across Norway so demands to limit sea lice were not then on the angler’s agenda.
I will be diving deeper into Norwegian catch trends over the coming weeks.