Veteran view: Intrafish published a commentary from eight veterans (average age 70) who have worked at varying times alongside the industry who have spoken out to label salmon farming as animal cruelty and unethical food production. They say that production in open cages leads to stress, disease and mortality. Emeritus professor Trygve Poppe (76) said that it is our duty as academics to speak out when something is going in the wrong direction. Unfortunately, I believe that it is exactly this academic involvement that has led to the situation that these veterans criticise.
The veterans come from a range of organisations that still influence the direction the salmon farming industry takes. These include the Institute of Marine Research, The Norwegian Institute for Nature Research, the School of Veterinary Medicine and the Norwegian Food Safety Authority. Unfortunately, whether the connection is through these veterans or today’s leading scientists, the application of academia to salmon farming has not been a great success. This can be seen from the one example that the veterans discuss and that is sea lice.
As NASCO have highlighted in their review of sea lice, there are over two thousand published academic articles on sea lice but less than twenty that use real data. Much of the problem is that much of the work is either lab based, theoretical or modelled none of which reflect the unique lifestyles of parasites. This is why a real-life application like the Traffic Light System has failed simply because it relies on too much academic science and not enough common sense. The Scottish Sea Life Risk Framework is even worse because a model is at the heart of its application,
However, there is another reason why these veterans’ comments should be ignored, and this is highlighted in another commentary in Intrafish written by Jan Arve Gjovik, author of the excellent Aquablogg website. His commentary is titled ‘Veterans with a poor memory’. He writes that Trygve Poppe and his colleagues are highly critical of the salmon farming industry for engaging in animal cruelty and it rightly could be said that some of the current sea lice delousing practices are exactly that. Yet these veterans should also be highly critical of themselves because it is these veterinarians and members of the Norwegian Food Safety Authority who are responsible for introducing a delousing programme that is incompatible with good fish health.
Jan Arve describes how researchers from the National Veterinary Institute determined the level at which the sea lice limit should be set on salmon farms. This was based on a theoretical model but as regular readers of reLAKSation already know, my view of models that have anything to do with sea lice are likely to bare little relation to reality and so it seems in this case. However, because the work was published in an academic journal it seems the salmon farming industry have had to accept it as truth and suffer accordingly
In 2001, the two researchers, Heuch and Mo calculated that in 1986/7, which was before sea lice were being blamed for decimating wild salmon, that sea lice on wild fish produced 2.6 billion eggs. This they considered to be the background level, but they also believed that wild fish could withstand twice this load. Ie 5.2 billion eggs. Using farmed production levels from 1999, they concluded that the maximum number of sexually mature female lice on farmed salmon should be set at 0.05. Jan Arve says that the initiative for strict sea lice limits came from veterinarians who wanted to look after wild salmon at the expense of the salmon on farms. He also points out that these veterans also have a responsibility for assessing the veracity of the research that is the basis for today’s lice management, which as we know is without scientifically sound justification. Critically, it doesn’t not have any effect on wild salmon but has a dramatic effect on the health of farmed salmon.
Jan Arve doesn’t make much comment about the Heuch & Mo paper other than what is said above. Sadly, the academic world was too quick to accept this work without questioning its rational and hence it has been adopted by regulators who equally just accept the numbers as reflecting the real-life picture.
In their paper Heuch & Mo describe their ‘simple’ model as covering an area of coastline of 1500 km in length. Their model is based on seven assumptions (although I suspect there are more):
- The total number of sea trout in this area is estimated to be 1 million fish of which 700,000 were in the sea during the period April to June. These fish are said to carry 3 lice each. This number comes from another paper by Schram from 1998. It seems that the 3 lice per fish is calculated from sampling wild sea trout around the Island of Tromøy over four years from 1992 to 1995.The fish sampled were actually quite large weighing an average off 440g. In 1992 just 60 fish were sampled with 146, 184, and 112 sampled in subsequent years and over a time period of five or six months. This means that typically just 20 fish a month were sampled. For a variety of reasons, such numbers are clearly not representative of the wild fish population.
- The second assumption is that 50,000 mature wild salmon have returned to Norwegian waters. These are assumed to carry ten lice each. This assumption is based on a student thesis and one from Berland in 1993. These were fish primarily caught by fishermen and were big fish ranging from 50cm to 110 cm in length. Unfortunately, whilst Belrand described the fish as being infected with from between 1 and 94 lice, the spread is not actually given. However, I suspect like the sea trout data, this infestation does not provide a truly representative picture of sea lice infestation. It is also worth remembering that some of these fish could have been at sea for three years or more.
- The third assumption is that there are 1.5 million escaped farmed salmon each carrying ten lice. This data comes from published reports from NINA, but it is an assumption too far to suggest that just because the fish come from a salmon farm they are already infested with at least ten lice. It is difficult enough to get today’s researchers to understand parasite ecology, so back in 1998, there was no understanding of why this assumption is wrong.
- The next assumption is that Arctic char are not part of the infestation equation
- The number of salmon in the area is calculated as the standing stock minus 20% due to slaughter.
- The lice load on wild salmon equate to the official lice limit. They assume that farmed salmon are carrying more lice than is tolerated by the authorities.
- Lice on wild salmon carry more eggs that lice on farmed salmon.
The paper goes on to describe the model by calculating the number of lice on wild hosts multiplying the number of salmon by the average number of lice and so on. This is totally wrong so from the very first calculation, the model is flawed. Lice are not evenly spread throughout either farmed or wild populations. Based on just this simple fact, the estimates that conclude that the lice limit should be 0.05 females is nonsense. It is unclear how these eight veterans have not yet reached the same conclusion.
Although the paper suggests a lice limit of 0.05 female lice, the Norwegian Government had in the previous year implemented a lower limit of 0.5, which was down from 2 which had been brought in 1998.
In his commentary Jan Arve highlights that the reason that the 0.5 lice limit was so readily accepted by the authorities was because salmon famers had a weapon in their armoury that enabled them to achieve the 0.5 lice limit. This was Slice, the anti-lice treatment. However, those advising the authorities at the time gave no thought to the implication of having to repeatedly use Slice to maintain low lice levels on farm. This was that the lice would eventually become resistant to Slice invalidating its effectiveness.
Without an effective treatment and with regulations demanding low lice limits, farmers were forced to move to mechanical delousing, the consequence of which is stress, physical damage and mortality. Jan Arve highlights another paper. This one from the Norwegian University of Life Sciences in which 453 dead fish were analysed at between 1 day and 13 days after delousing. They concluded that the cause of death was not always attributed correctly by the farmer and thus current practices for recording mortality may overlook the long-term negative effects of delousing. They suggest that guidelines for farmers to more accurately record the cause of mortality following delousing are necessary to improve the knowledge of the process.
However, what is surprising is that despite the concern expressed by the veterans about animal cruelty and the publication of yet another academic paper about the causes of mortality, there has not been an urgent response from the Veterinary Institute etc that there needs to be an urgent debate about whether 1. Sea lice limits are actually necessary and whether they achieve their aim and 2. Whether salmon farms should be forced to treat their fish for sea lice to maintain some theoretical limit. It seems that everyone has expressed their concern about high mortality levels in salmon farming but despite the clear knowledge that it is the consequence of a flawed sea lice policy, the regulators seem to want to continue with it to appease the unrealistic demands of the wild fish sector.
I welcome anyone to the debate but if their only contribution is to criticise a flawed policy rather to facilitate change then perhaps these veterans should accept that they have retired and move on to some other activities.
Tanavassdraget: Two recent articles by the excellent Aquablogg have looked at the situation for wild salmon in PO13. In the first, it has been pointed out that whilst the Traffic Light System has emphasised that lice induced mortality of wild fish is at zero, by awarding a green rating, wild salmon stocks in the area have collapsed, especially in the River Tana. The latest Aquablogg continues the story by highlighting that the number of returning salmon to the river was in 2024 just 9,000 salmon when the spawning population needs to be at least 30,000 fish. Even VRL write that after the 2024 season, it became clear that the situation for salmon in the Tana is more serious than previously assessed. This is despite writing in 2020, that overfishing has been reduced and the reconstruction has begun. Obviously, VRL’s idea of reconstruction is to see the number of salmon plumet even further. Aquablogg highlights that it is however not just the Tana’s salmon that are in trouble in the region.
In reLAKSation no 1232, I wrote about the status of Norway’s salmon rivers, and I said that this is a subject that I would revisit. I admit that my knowledge of salmon rivers in Norway is not great, but I have tried to pull together any published information to see if I can make sense of what is available. It has not been easy. I have begun this journey in Finnmark in Northern Norway, which is assigned the designation of production area 13 (PO13) for the Traffic Light System.
It appears that unlike Scotland, there is no guidebook to all the salmon rivers of Norway. I have therefore referred to a number of sources for information on which rivers are located in this area. These include the Sea Lice Expert Group list of rivers for each production area. VRL’s 2020-2025 river assessment document. The website Salmon Atlas and their ‘The Atlantic Salmon Rivers of Norway’ and finally, NASCO have just released a new interactive guide ‘The Wild Atlantic Salmon Atlas’.
In total I have arrived at a list of nineteen rivers for Finnmark, all of which appear in the NASCO salmon atlas. The Expert Group list includes just 18 of these whilst VRL list 17. The Salmon Atlas website lists just six.
In addition, VRL list a further 5 rivers, four of which are tributaries of the River Tana but interestingly, Statistics Norway include a further 19 rivers although none of these have any data and are likely to be small rivers and tributaries.
What is interesting from this data is that NASCO have rated salmon populations in six of these rivers as being as high risk, yet VRL have rated them as 0 which means that stocks are not only sustainable, but that fishing can be increased. A further 3 rivers fall into this category but are only at moderate risk by NASCO.
In the annual report on the status of Norwegian salmon, VRL have produced graphs for the numbers of salmon returning to various regions of Norway. These are south, west, middle and north. These cover quite a large area and a variety of rivers. They also produce a separate assessment for the Tana River in Finnmark. I was interested to see that for the Tana they also offer a different graph comparing the numbers returning to the Tana compared to those returning to Northern Norway. This is expressed as the percentage change since the situation in 1989. This suggests that in 1989, the situation for the Tana was very different then but I suspect not. I believe that these percentage change graphs can often mislead, and this is why I prefer to use the raw data.
This is the graph from the latest VRL report.
This contrasts with the version from the 2016 report.
I don’t have access to this full data series, but I have the data for Finnmark showing the numbers returning against the catch
What this shows is that catch is declining faster than the decline of the returning stock. I have also plotted the catches from all Finnmark against those from the Tana.
Looking at the longer trends, VRL say that the situation in Northern Norway is much better than that of the Tana. However, in the recent editions of their report, they begin to admit that in the last decade, the situation is deteriorating across all of the north.
Of all the rivers in Finnmark, fourteen have good series of catch data to analyse. When looking at the longer-term trends from 1993, five of the 14 rivers show a declining trend, whilst the remainder show increased catches.
Yet on closer examination, all the rivers have declined in recent years. Not one has maintained an increased catch. This decline coincides with the introduction of the Traffic Light System, which has always been green despite the declining catches. Whilst there are salmon farms in Finnmark, they are clearly having no impact on the local fish populations. There is something else at play. Certainly, VRL have placed pink salmon as increasingly high risk to native Atlantics although how much direct impact there might be is uncertain.
However, this year iLAKS report that a 400-metre-long trap has been placed across the Tana River. Two years ago, around 170,000 pink salmon were recorded in the Tana. It will be interesting to see whether the pinks can be prevented from reaching their spawning grounds and what impact they have on the Atlantics salmon. As pinks are on a two-year cycle they did not return last year and yet the number of Atlantis returning to the Tana fell by nearly half from 20,000 to just 9,000.