It escapes me!: In last week’s reLAKSation, I highlighted that the Norwegian Scientific Committee on Salmon Management placed escaped farmed salmon alongside sea lice as the greatest threats to wild salmon. By comparison, the UK’s CEFAS considered such impacts from salmon farming as much less of a threat to wild salmon than say predation, which the Norwegians don’t even consider a threat at all.
My own view is that the threat to wild salmon from farm escapes is almost negligible and it is just another excuse to deflect attention away from other threats and onto salmon farming. Even if a farmed escape did mange to breed with a wild salmon, any negative attributes, if there were any, would never survive. Seemingly to those who consider escapes to be a threat, Darwinian evolution doesn’t apply to farmed salmon.
I am prompted to mention this because of a new report from Marine Scotland Science about the investigation of the hybridisation that occurred following the ‘large-scale’ escape from Carradale in 2020.
The results can be summed up very simply. None of the fish that escaped migrated up any of the rivers investigated and successfully bred with a wild salmon. As usual, a vast amount of resources have been invested in a study of something that rarely happens just because the angling and wild salmon sector continue to blame salmon farming for all their woes and want to deflect attention away from their own impacts on wild salmon populations.
The report (published as Scottish Marine & Freshwater Science Vol 13 no 2) states that 48,834 fish of average weight 4.2kg escaped from the farm during Storm Ellen. Following this escape, a genetic survey of salmon fry from all the rivers around the south-west of Scotland was undertaken in 2020 and 2021. Other samples were taken from nearby rivers in England. In total 118 sites were fished with 2,390 samples taken in 2020 and 2,932 in 2021. Another 338 samples were taken from 10 sites in England. In total 5,322 samples were taken of which 41 were discarded following quality control checks. Of all the samples, 99.2% were successfully genotyped.
THE RESULTS
One fish was identified as a hybrid farm wild salmon. This was caught in 2020 from the River Clyde and it was discounted as having anything to do with the Carradale escape.
One fish was identified as a possible hybrid caught from the River Eden south of the border
That’s it. Just two suspect fish out of 5,281 and neither attributed to the escape. No juvenile fish were caught that might be described as the product of a cross of fish from the Carradale escape.
THE CONCLUSION
Marine Scotland Science concluded that there was no evidence of any hybridisation following the escape, however, having expounded their theory about the impact of escapes for so long, they just cannot admit that escapes represent a very minor threat to wild fish.
The report suggests that the lack of hybridisation does not mean that this escape did not have any negative impact on wild fish. They say hybridisation could have occurred further afield or that the fish were too immature at that time to breed. This report is a lot of ‘if’s and but’s’ and not much else. Surely, these findings are yet further proof that Marine Scotland Science’s efforts would be better served researching the other threats to wild salmon rather than wasting more resources on trying to implicate salmon farming in the declines.
Finally, I note that the report says that it was estimated that a minimum of 3,000 of the escaped salmon entered Scottish rivers. This estimation comes from Fisheries Management Scotland whose ability to count fish has already been questioned given the huge discrepancies in the number of caught fish that have been recorded in their Annual Review compared to that which appears in the official Scottish Government data. FMS’s estimation is based on 295 fish recorded by anglers, most of which were caught in the Leven, one of the least likely rivers to be affected.
Surely, this report is yet another indication that all the claims made against salmon farming are not supported by any hard scientific evidence. Perhaps this is why Marine Scotland Science have not publicised this report, preferring to publish it in the run up to Christmas when everyone is more focused on the holidays ahead.
Pressures: The commentaries in reLAKSation are usually in response to coverage in the wider media. However, sometimes other sources also require a comment and so this week, I would like to discuss one aspect of the recent SEPA workshop on the sea lice risk framework. This was open to anyone of interest and the presentations have been shared. There was certainly no instruction to consider the discussion as being confidential.
One of the presentations offered an insight to the level of infestation of wild fish that might be considered as a threshold above which measures might be taken against local farms. The following image is taken from one slide of this presentation and suggests that there should be no more than 2 mobile lice on a 25g fish.
This exposure level prompted a number of questions as to why other pressures that have been identified as having an impact on wild salmon and sea trout are not being as tightly regulated, especially as SEPA have previously admitted themselves, sea lice from salmon farms are not responsible for the decline in wild fish numbers. It was felt that the salmon farming industry was being unfairly targeted despite clear evidence that salmon farming has little impact on wild fish. As has been repeatedly pointed out, Marine Scotland Science refuse to discuss the science and SEPA follow their lead.
I have analysed all the lice data published by both Marine Scotland Science and Fisheries Management Scotland from 1997 to present. This amounts to 24,461 fish in total. Of these, I would suggest that just 52 fish meet the exposure level suggested by SEPA as being at risk from lice infestation. This equates to 0.2% of the total number of fish sampled by the various west coast fisheries trusts.
It is impossible to compare this impact with the effects of dams or afforestation simply because there has never been any serious attempt to measure the impact of any of the other pressures. The only other pressure where there is a measurable impact on wild fish is exploitation because the number of fish caught by any method has been recorded by Marine Scotland Science. Unfortunately, the angling fraternity do not believe that their activities have had any impact on wild fish numbers. Just last week, the River Tay Fisheries Board published their annual report which states:
The Board has sympathy with the view that the actions of anglers have received a disproportionate focus in relation to the other, much more serious, pressures that salmon face.
I wasn’t aware that the action of anglers has received any focus compared to any other pressure. The wild fish lobby point to the 95% of salmon and 87% of sea trout that were released in 2021 with the River Tay Fishery Board claiming that ‘it is preferable that anglers should release fish because they want to, rather than being compelled to, especially since the small number of extra fish spawning, would make no practical difference now’.
Yet, SEPA appear to argue that protecting small numbers of fish (from sea lice) is necessary to safeguard the whole stock, despite SEPA’s Head of Ecology, Peter Pollard, telling the Scottish Parliament that sea lice from salmon farms are not responsible for the decline in wild fish numbers. In 2021, anglers caught and killed 634 salmon and sea trout from rivers around the salmon farming area. This is significantly more than the 52 fish that I have identified.
However, such comparison is misleading, and this is because the 52 fish I identified were from 25 years’ worth of data not just from 2021. On this basis, then the comparison should be that since 1997, anglers have caught and killed 35,184 salmon and grilse and 60,535 sea trout from rivers within Scotland’s salmon farming area. This is a total of 95,719 fish.
The question is therefore which of salmon farming or exploitation has had the bigger impact on wild fish? Of course, just because a fish is exposed to the SEPA threshold does not mean that it will die from lice infestation whereas, knocking a fish on the head to kill it certainly does.
64.5%: In the section titled About Us, Wild Fish Conservation, formerly the Salmon & Trout Association begin with the statement that “Wild fish populations are in decline. In fact, the Atlantic salmon has declined by 70% in Scottish rivers since 2000. We exist to reverse this trend.” Although the reality is that they exist to support salmon and sea trout angling in the UK.
The statement about the decline in wild salmon is repeated in WFC’s Off the Table campaign website. In the section titled ‘Get the facts’, WFC say that ‘Atlantic salmon have declined by 70% in Scottish rivers since 2000. Industrial salmon farming is one of the causes linked to this decline.’ Yet whilst they say that it is only one of the causes, it is the only one about which they campaign. There is no mention of any other possible cause because in their eyes, it is only salmon farming that needs to be removed.
Before I delve into the question of whether salmon farming is one of the causes of wild fish declines, I can only wonder why WFC have selected the year 2000 as a point in time from which any decline is measured.
The graph produced annually by Marine Scotland Science that illustrates the annual catch of salmon clearly shows that against a background of increasing catches prior to 2011, there is much annual variability.
The year 2000 saw catches dip to 45,142 fish. This means that far from the 70% decline WFC claim, since 2000, catches have declined by just 21%.
The reality is that salmon catches peaked in 2010 with 111,405 fish caught. Between then and now, total catches have declined by 67.9%, which WFC have rounded up to 70%. The question asked at the start of this commentary was whether salmon farming is responsible for any part of these declines.
Marine Scotland Science certainly believe that there is. In their report of 2016 concerning the analysis of catch data to determine the impact of salmon farming on wild fish, Stuart, Middlemas, Gordon Smith and John Armstrong state that ‘From roughly 1990, the farmed areas decline relative to non-farmed areas, which is consistent with their being an impact of salmon farming on wild salmon’. However, they then fail to explain why from the late 1990s, salmon catches around the salmon farming area have increased. They also fail to explain the similar decline in catches from the mid-1960s when there was no salmon farming on the west coast. I have previously discussed these discrepancies in past issues of reLAKSation but would welcome the opportunity to discuss them with Marine Scotland Science face to face, something Marine Scotland Science appears reluctant to do.
WFC have focused on what has happened to wild salmon stocks in more recent years and I would argue that the interesting aspect of these declines is what has happened since salmon catches peaked in 2010. Even the Convenor of the Tay Salmon Fishery Board admits in their latest annual report ‘That salmon are in worrying decline is beyond doubt’. This is the convenor of Scotland’s biggest salmon river and one that is located hundreds of miles from the nearest salmon farm.
As mentioned above, the total catch from 2010 has fallen by 67.9%. Early indications are that 2022 was a better year for catching salmon than 2021 but as the MSS graph shows, there is always some annual variability in catches and one better year does not suggest that wild salmon are not heading towards extinction.
It might have been a coincidence, but Marine Scotland Science published their report about the comparison of catches from east and west coast rivers shortly after I had highlighted that the differences between the two coasts were not all they seemed. They said that it is very important to note that such analyses of fishery catch data cannot be used to prove whether or not fish farming has an impact on wild fish. Rather strangely, they did not say anything similar when the fisheries boards and trusts published a graph in 2011 showing that there was a difference between the coasts and that salmon farming must be to blame.
In their 2016 report, Marine Scotland Science stated that there are many other factors that may cause changes in fish population, and these may differ between the two regions. They added that for example, catches of sea trout have declined over recent decades on both farmed and non-farmed areas in Scotland and it is plausible that different factors are responsible in the two regions.
Of course, it is plausible that a river blocked by a major hydro-electric dam may have lower productivity than another river nearby but the possibility that the causes of declines across the whole west coast compared to the whole east coast are due to different factors is remote. It is at least six years since this report was written which would allow plenty of time for Marine Scotland Science to identify such differences. I doubt that they have even made an effort to do so.
Anyway, I would like to get to the crux of this commentary and that is if the decline since peak catches in 2010 is compared for the salmon farming and non-salmon farming areas then whilst the overall decline is 67.9% as stated above, the decline in salmon farming free areas including the east coast is 68.2% whilst the decline within the salmon farming area is just 64.5%.
What is more interesting is that when catches are tracked from 2010, the trajectories match each other, as can be seen in the following graph.
I defy anyone from Marine Scotland Science or the wild fish sector to tell me that it is plausible that different impacts are responsible for the declines in either area. Equally, I defy anyone to tell me that salmon farming is responsible for the declines in both areas. As mentioned above, in 2011 the fisheries trusts (under the umbrella for RAFTS) compared catches from east and west coasts and produced the following graph:
RAFTS concluded that there is a clear trend of declining salmon catches, compared with catches on the East coast, in areas where the Scottish aquaculture industry operates. The assertion by SSPO that ‘the catch statistics show salmon farming has had no effect on wild salmon catches’ does not stand up to scrutiny.
I will repeat again, what I have said many times before. Wild salmon numbers have declined because fish are failing to return from their feeding grounds. As the now King Charles said in 2017, we don’t know why. As we approach 2023, we still don’t know why, and little effort has been made at all to find out why. After all, why bother when there is a salmon farming industry to blame.
Spill the beans: A significant part of the narrative used against the salmon farming industry is that a soup of sea lice larval disperses away from salmon framing infesting all the wild fish they encounter. Unfortunately, this soup has never been identified, yet the concept remains firmly entrenched in the many models developed to support the sea lice narrative.
Part of the SPILLS project was intended to identify the larvae in the water column. When I somewhat belatedly became aware of the SPILLS project, it was because I was told that the report would be published at the end of September. It wasn’t.
September has been and gone as have October and November. Although as I have related, some of the findings were publicised at the Sea Lice 2022 meeting and they did not suggest that the findings lived up to expectation.
I have been led to believe that publication has been delayed because reviewing the data has taken longer than expected, yet how long does it take to review data that wasn’t found? Given the amount of time and money invested in developing the sea lice models, in my opinion, any delay is simply to try to turn this bad news story into good news.
I heard this week that publication is now intended for the 19th December just in time to bury it when everyone is likely to be more interested in the Christmas festivities.