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reLAKSation no 1109

SPILLS too: Another week has passed by and not a word as to when the SPILLS report will be published. I apologise for focussing on this document, but it is of significant importance as it will, or will not, show whether the models produced to implicate salmon farming in wild salmon declines, have any validity. The initial results presented at Sea Lice 2022 would suggest not and the only conclusion that can be gleaned from the delay in publishing the report is that Marine Scotland Science are trying to create a good news story out of bad.

Meanwhile, whilst we wait for this report to be published, I will continue my look at the data from the project that is already in the public domain. The SPILLS project website states that historic sentinel cage data will be used to validate the sea lice dispersal model.

The historic sentinel cage data has already been published as it was generated between 2011 and 2013 from 11 sites located throughout Loch Linnhe.

Out of the eleven cages, two did not provide any data leaving just nine to analyse. Oddly, the spreadsheet listing the data was updated on 1st December 2022 which begs different questions as to how data from 2011-2013 can be updated?

In total, 3,880 fish were sampled over the three years and the sea lice infestation for all the fish is shown in the following graph. Although the fish stocked in these cages were salmon, the number of fish carrying more than the Well’s threshold for comparable sea trout is just 108 fish or 2.8% of the total fish stocked.

However, this data is slightly misleading as the trials were divided into two periods. These were during May and then in October. Several published papers have focused on the interactions between salmon farms and wild salmon during May and June as this is usually when salmon migrate out of the natal rivers. If just the data for May is selected out, the distribution of lice on 1,623 fish shows a similar pattern to the complete data set, but with an even more compact spread of lice. The maximum lice infestation being just 4 lice which was on just two fish. All fish sampled fell well below the Well’s threshold.

Following on from earlier studies, the fish were intended to be exposed to potential lice infestation for a one-week period, however, the sentinel cages were deployed over varying periods of time (counted to include day of deployment and day of recovery) as shown in the following table:

Clearly, increased time in the sea might lead to increased infestation pressure but more importantly different exposure times makes comparison between cages more difficult. In addition, the sentinel cages were deployed at different depths between 7 and 22 metres below the surface. This also makes direct comparison more problematic.

I have plotted the lice distribution for all nine cages, and all are similar.

The clear message from these analyses is that the infestation pressure on migrating salmon smolts is extremely small. However, what the data doesn’t show is whether the fish in the cages were infested by larval lice dispersed on the currents and wind or from passing fish.

Whilst sentinel cages have been promoted as a way of measuring lice infestation, the reality, is that migrating salmon smolts are likely to have travelled through this location within one day, not a week.

The sentinel cage data supports the data previously discussed from sampled wild fish that the focus on sea lice as a way of protecting wild salmon stocks is totally misplaced. The risk to migrating smolts from sea lice is clearly extremely small.

In the next issue I will discuss the final aspect of the SPILLS project – the plankton tows. Perhaps by then, the SPILLS project report will have been published!


Unreliable: There has been a great deal of reaction to the publication of a peer-reviewed report in Canada that concluded that sea lice on farm-raised salmon does not impact sea lice on wild juvenile salmon in British Columbia. Of course, most is negative, and this is to be expected. Those opposing salmon farming, for whatever reason, cannot accept that their claims as to the alleged impacts of salmon farming may be wrong.

However, the most interesting reaction comes from Alexandra Morton, who spoke to CBC News saying that in the face of an enormous amount of evidence, the salmon farming industry continues to deny something as simple and obvious as the impact of sea lice. She added that the conclusion reached in the latest DFO study reflects unreliable sampling data provided by farmers and the consulting firms hired by them.

It is sad that like many other critics, Ms Morton feels the need to attack people rather than address the science.

If data from the salmon farming sector cannot be trusted, then I will look to Ms Morton’s Salmon Coast Field Station own data instead. The Field Station has been collecting sea lice data from wild salmon since 2001. In total, they have examined 47,474 fish. I don’t know how this compares with the size of the industry data but nearly 50,000 fish is a good sample size for analysis. I have carried out this analysis previously, but the data now includes sampling for 2022.

The first graph shows the sea lice counts on all 47,474 fish expressed as a percentage of the total fish caught.

When the data is divided into the two main species of Pacific salmon Chum and Pink, the pattern of infection is similar.


What these distributions tell us is that about 90% of sampled fish have zero lice (60%) one louse (20%) or two (10%).  Interestingly, the Salmon Coast Field Station sea lice report for 2022 discusses numbers of lice (average 1.4 although I calculate it to be 0.98) and numbers per location. What they don’t discuss is the impact of lice levels on these fish. I have been using the Wells threshold for harm as a measure because MSS tend to use it, although I would argue that this work is significantly flawed. Wells sets the threshold at 13 lice which equates here to just 301 fish. I understand that there is some Canadian work that has suggested 7.5 lice on a 0.7g Pink salmon might be lethal (Jones et al 2009). This would equate to 1,089 fish or 2.3% of the sampled fish.

Therefore, according to Ms Morton’s long-term data, just 2.3% of migrating salmon are at risk from sea lice. It could be argued that salmon farms are not only the sole cause of sea lice, but they are also in fact not to blame at all.

I would be more than happy to discuss this analysis with Ms Morton. My door is always open.


Endangered:  The Guardian newspaper recently wrote about some of our endangered foods and that includes wild Atlantic salmon.  The article is based on a book by BBC Food Programme presenter Dan Saladino titled Eating to Extinction.

In the section about salmon, Saladino writes that salmon have been so heavily fished that the population has become depleted. Equally, rivers have been transformed by dams and pollution and the seas are affected by climate change and acidification. He adds that numbers of salmon in England were the lowest on record and the fish has disappeared across many rivers in Europe and the north Atlantic.

However, Saladino says that there is still plenty of salmon to eat in the form of farmed salmon, but he says that they are genetically different and there are fears that far from saving wild salmon they are contributing to their decline. The Guardian quotes reports of lice and escapes impacting wild salmon stocks.

Of course, this is not to be unexpected, because it is the well-established narrative put out by the wild fisheries sector and if proof of such is needed, then I am reminded that Dan Saladino presented an edition of the Food Programme in February 2020; A tale of Two Fish – Salmon, the wild and the farmed. In the programme, Saladino talks to Mark Bilsby, CEO of the Atlantic Salmon Trust about genetic introgression. Mr Bilsby describes farmed salmon as a domesticated animal bred for the farming and ‘they are not like a wild fish at all’. He said that they are still salmon, but a domesticated version of salmon. Yet he then goes on to say that if they escape, then farmed salmon can migrate up the rivers to breed with wild salmon. In fact, just like wild salmon.

Mr Bilsby continues that this interbreeding then dilutes the ‘genetic gene pool’ so the fish aren’t as fit for their environment and are unable to cope with change. Consequently, the population declines overall. He re-enforces this message by saying that the Norwegian Government rank the threat of genetic introgression as the greatest threat to wild salmon.

Actually, Mark Bilsby should have said that it is the Norwegian Scientific Advisory Committee for Atlantic Salmon who rate genetic introgression as one of the greatest threats to wild salmon, not the Norwegian Government. Four members of this committee work for NINA, the Norwegian Institute for Nature Research. I mention this because Aquablogg has just highlighted a new report from NINA titled ‘Establishment of a salmon stock in a region with intensive salmon farming.’

This describes the spontaneous establishment of a viable salmon population in the Uskedal river in the middle of the Hardangerfjord. The river was heavily limed in 2002 to combat acidification after losing its resident salmon stock. The new population is said to be a combination of escaped farmed salmon and strays from other rivers. Observations described in the report show that the stock is self-reproducing and that the crossing of hereditary characteristics from escaped salmon has produced salmon that are no different to other fish in the region. No damage to the stock has been detected.

Aquablogg points out that researchers in the wild fish sector have been challenged many times to prove that wild salmon are genetically different in each river. In the same way, they have been challenged to explain how salmon have become spontaneously re-established in a river in Norway’s worst fjord for lice. Equally, other natural stocks of salmon and sea trout appear to be doing well elsewhere in the same (sea lice ridden) fjord. Aquablogg suggests that there is no desire to answer such questions because they are at odds with the established narrative that these scientist support. Aquablogg suggests that one reason why might be that if stocks are shown to be healthy, then there is no need for any further research funding to these scientists.

Finally, Aquablogg poses the question why this report only covers the period up to 2015. Why has it taken seven years to publish this report and what has happened to the river since?


The truth: There has been an exchange of letters in the West Highland Free Press which has cumulated in a letter from Dennis Archer of Coastal Communities Network Aquaculture Group who quotes SEPA as saying that ‘sea lice from salmon farms pose a risk to wild salmon’.

Mr Archer the writes: This is the truth, and every salmon farming company knows it and so does Martin Jaffa. Why cannot they admit the truth?

Mr Archer speaks of the truth but provides not a shred of evidence to support what he sees as the truth. In fact, he is not alone, as over the years, I have been widely criticised for questioning the established narrative but not one single person has yet come back and shown me any evidence that supports their claim. Even Marine Scotland Science seemingly are unable to supply any clear-cut data. It is all conjecture.

And when it comes to the data which I use, which is not even my data, then those who supposedly seek the truth simply dismiss it as junk.

As a member of the CCN Aquaculture, Mr Archer could have had an opportunity to debate the issues with me face to face, but my offer to speak to his group was rejected.

Sooner or later, the salmon farming critics are going to have to offer something more than a narrative that says that before salmon farming there were healthy stocks of salmon, and now salmon farms are here, wild salmon have disappeared.

The truth is wild salmon are in decline across all of their range, including areas where there are no salmon farms.  Attack the salmon farming industry as much as they like, but the real truth is that all they are doing is deflecting attention away from the actual reasons why wild salmon stocks are in crisis.

If anyone wants me to change my mind and accept their truth, then I would need to see a little bit of evidence first, than just a narrative.