reLAKSation no 1070

Lice attack: This week the Watershed Watch Salmon Society tweeted that salmon farm lice had spread from open-net salmon farms to the offices of BC Premier John Horgan and MP Patrick Weiler.

This is part of the activist programme to keep salmon farms in the news as the Government contemplate whether to extend the current licences or not.

Alexandra Morton has also been trying to pile on the pressure and has recently been tweeting video footage of why BC salmon farms should be removed to help protect wild salmon. As might be expected, the video includes images of young salmon covered with lice.

Identification of the various sea lice life stages from a small screenshot is not easy but these lice look to be mainly pre-adults and some adults. The fish appear to be infested with about 15 lice each, at least that is the number that are visible. Presumably there are more on the other side of the fish.

Alexandra Morton’s Salmon Coast Field Station conducts regular sampling of wild fish to monitor the number of sea lice on migrating wild salmon, mainly pink and chum salmon. This sampling has taken place every year since 2001. In total, they have sampled 44,530 fish, recording the number of lice on each one.

The following table records the total number of fish from the 44,530 samples that have the highest number of lice for each of pre-adult males, pre adult females, adult males, and gravid and non-gravid females.


No of lice PA male PA female Adult male Non- gravid Gravid
4 7 7 18 5 3
5 4 1 4 4
6 2 3 4 1
7 1 1
11 1
13 1


The top line shows that the number of each fish infested with four lice are 7 pre-adult males, 7 pre-adult females, 18 adult males, 5 adult non-gravid females and 3 gravid females. The second line is for 5 lice and so on.  These are the total number of infested fish from 21 years of sampling and number 67 fish in total out of 44,530 fish.

With so few fish carrying even relatively small numbers of pre-adult and adult lice, it is a real puzzle how the video managed to show three fish with such high lice counts, and even more remarkably, three fish that had been caught at the same time.

The question of how common it is to catch highly infested fish has been addressed previously in Canada. The Broughton Archipelago Monitoring Plan (BAM) asked this question about an image that appeared in National Geographic magazine in October 2010 and was subsequently widely distrusted throughout the media.

The BAMP team, which included six scientists from a range of institutions and companies, calculated that based on sampling from over a decade, finding a young salmon with more than two adult female lice was 1 in 800. When the calculation was applied to just pink salmon and ‘lep’ sea lice, the chances increased to 1 in 5,700 fish. There are some caveats in the calculation, but the numbers shown here give an idea of the chances of finding such an infested fish.

What is interesting is that one of the BAMP team who were involved in the calculation as well as other facts that might bring some of the claims made by activists into question, was Dr Martin Krkosek, Alexandra Morton’s most long-standing colleague.

I have looked at the Salmon Coast Field Station data and I calculate that the chances of finding more than two adult female lice on a fish is 1 in 873.

Alexandra Morton has also tweeted a second video in which she claims to show what happens when salmon farms are removed from the sea as happened in the Discovery Islands. The video shows Ms Morton looking from a glass aquarium at fish that appear to be free of sea lice.

In the video Ms Morton says that for the first time for many years, juvenile salmon can swim out to sea unharmed rather than being killed by sea lice. She says that she has made the trip down to the Discovery Islands to see this for herself. The previous year she said that migrating sockeye had a 100% infection rate with an average nine lice per fish and similar observations were made for chum and pink salmon. She added that she couldn’t believe that one year later she would be seeing such beautiful and heathy (sea lice free) fish. She says that it couldn’t be clearer, no farms no lice.

Her comments make it sound as if she has never seen a juvenile salmon which is not infested with sea lice. This is rather odd because the analysis of the full data set from Salmon Coast Field Station shows that 26,782 of the fish sampled were totally free of lice. A further 9,244 fish were found with one louse.

When the infestation rates for the Salmon Coast Field Station data is presented as the percentage infestation for increasing number of lice, the graph appears as follows:

This is a typical graph of an aggregated distribution and is not of any surprise because this is the type of distribution that, as I have increasingly shown, is common to sea lice. Most fish have no or very few sea lice and a few fish have many. Typically, when ‘biologists’ sample for sea lice, it is this few fish they tend to catch, and they then assume that all fish are infested in the same way.  They seem to forget all the other fish caught that have no lice at all.

How much longer does the salmon farming industry have to endure accusations from those who refuse to acknowledge that the science doesn’t support their claims? It is not just the activists who remain blinkered but many acknowledged scientists working in other salmon farming countries.


Regional: Last week, the Norwegian Aquablogg published a commentary claiming that the Traffic Light System makes a mockery of the science. They are not wrong.

Included in the commentary were analyses of lice counts in different regions of Norway as shown in the following graphs:

These also show the classic aggregated distribution. I have since started to breakdown the Scottish sea trout data compiled by Marine Scotland Science into areas. In all, there are 100 different sampling sites, even though the main RAFTS study was carried out at 28 sites.

Thirty of the sites that appear in the full data set run for just one year. Another twelve run for two and 9 are sampled over three years. Given that the sampling recorded here began in 1997, only six sites have runs of sampling of more than 17 years. Two are sampled for 23 years, although one of them consists of relatively few samples.

The most comprehensive data comes from Laxford and the graph of the data is as follows:

Yet again, another aggregated distribution!

Finally, I have also analysed the data from 2010 to 2018 collected from the site at Camus Na Gaul in Lochaber. The graph is not any different from the others.

This site is of interest because it is one regularly monitored by Lucy Ballantyne who appears in the FMS video warning of the dangers of sea lice to wild fish. Last year, Lucy told the Sunday Times newspaper that 85% of wild fish were infested with lice. Using this data, it means that 1174 fish are at risk of dying from sea lice even though not one of them was infested with any lice.


Fear not: SeaWest News report that dubious claims based on questionable science peddled widely by anti-aquaculture activists are causing unnecessary controversies over salmon farming in British Columbia (and elsewhere) leading to a waste of public resources. This is the conclusion of a new research paper published in the Journal of Aquatic Health which was published on April 6th.

By total coincidence, the Guardian newspaper reported just eight days later that following a multi-year access to information battle, a report about the spread of Piscine orthoreovirus (PRV) from farmed Atlantic salmon to Pacific Chinook by a federal biologist working for DFO, was released after supposedly being suppressed by the Canadian Government and the salmon farm industry.

This study was one of four cited in the new paper by Alaska Dept of Fish & Game’s principal fish pathologist and a veterinarian working for the North West Indian Fisheries Commission. They highlight that when molecular discoveries of new potentially infectious agents are publicised with supporting evidence of their effects on fish health or in the case of known viruses, whether their detection can be corroborated.

In the case of this widely publicised study, the problem was that the other two scientists investigating PRV with the federal biologist Dr Kristi Miller-Saunders did not agree with her conclusions. Consequently, the report was never published nor written up as a peer-reviewed paper. However, when the report failed to appear, anti-salmon farming activists developed their own narrative about how the salmon farming industry suppressed the study claiming that this unpublished report is yet further proof that net pen salmon farming should be closed down in British Columbia.

The authors point out that SUCH detections have received extensive media attention that have then been misinterpreted and followed by calls to change current health surveillance. The authors, Ted Meyers, and Nora Hickey, are joined by representatives of ten other organisations who have advised that any policy changes should only be made after further extensive investigation. This would avoid wasting resources monitoring for organisms that are not a significant threat to fish health or for non-infectious genetic material that does not represent a viable agent.

In her book, ‘Not on My Watch’, Alexandra Morton refers to Dr Kristi Miller and her cutting-edge techniques, yet the authors of this new paper clearly state that the advanced sensitivity of such molecular techniques can cause difficulty in interpreting the biological significance of any detections in fish.

Under normal circumstances, such detections would be just of academic interest. However, every paper that is published that might connect farmed salmon to declines of wild salmon is seen as an opportunity to lambast the salmon farming industry. Most of these papers are taken out of context and should really be considered as part of the wider science rather than as the whole story. This is the point of the paper which argues that just because any findings appear to support the activist’s narrative, it doesn’t mean that they provide the necessary proof. Other evidence is also necessary and required to build up a full picture of whether any organism is actually responsible for disease and mortality.

Meanwhile, the activists claim that Dr Miller’s report shows that wild salmon have been at the mercy of PRV for the last ten years. Its therefore a miracle that the fish she saw around the Discovery Islands are so beautiful and healthy when PRV is so entrenched in the environment.


SIWG: The wild fish sector continually refer to the recommendations of the Salmon Interactions Working Group suggesting that these were agreed unanimously. Included in the recommendations were the agreement to publish historic data from the wild fish monitoring programme, and wild salmon and sea trout catch data.

In March, Marine Scotland Science published the wild fish monitoring programme data (although there are some huge gaps) up until 2019. We are now in 2022 so there is now no reason why the data for 2020 and 2021 could not have been published.

As for the catch data, it seems nothing has changed. The 2021 angling season began in the second week in January that year and so far, there is no data available. Salmon farms are expected to publish lice counts weekly so why are not angling catches processed in the same way. The local district salmon fishery boards seem to manage to put out fishing reports weekly so why not catch data?

Fisheries Management Scotland, who were part of SIWG, publish an annual review which provides an early indication of the previous year’s catches. In 2021, the review appeared on March 23rd. This issue of reLAKSation is dated 23rd April and still no sign of the FMS 2022 review.