Ancestry update: In the last issue of reLAKSation, I discussed a new study which looked at the pace of genetic change in Norwegian rivers. The impression gained from the paper that genetic introgression from escaped farmed salmon was an increasing problem. This backed up claims from Vitenskapelig råd for Lakseforvaltning (VRL) who say that along with sea lice, escaped farmed salmon are the greatest threat to wild salmon.
The new paper had genotyped just under 7,000 scale samples obtained from fish caught from Norwegian rivers but there was no mention of the numbers of fish with a farmed salmon marker and those without. The researchers had said that:
We did not present the introgression in that way, because the estimates at the individual level are uncertain, and the method is also not precise at the individual level.
However, after further exchanges, the lead researcher kindly took another look at the results and found that out of the 6,926 samples, just 9.3% carried the farmed salmon marker and 90.7% were truly wild fish.
It seems to me that with less than one in ten fish carrying the farmed salmon marker, the threat to wild salmon from escaped farmed salmon has been highly over-stated. Much of the original concern about escapes arose from a time when technology was not as well developed as it is today, and escapes were more common. A constant drip of escaped fish may over time affect the wild population, especially one that is already experiencing significant declines, but escapes are now a much rarer occurrence, and any potential impact on wild stocks is much reduced. In Scotland, the number of escapes fell by 90% last year over the previous, which itself was marked by one single catastrophic event.
Research by the University of Stirling published in 2012, found that sustained introgression would need to exceed 20% to be even considered a threat, which is well above the current levels found in Norway.
River update: In the last issue of reLAKSation, I also discussed the claim that no salmon has been caught from the small River Strontian on Scotland’s west coast since the 1990s. This was blamed by some anglers as due to the impact of local salmon farms. I have since heard from the local fisheries management that whilst they do offer fishing in the river, the main local attraction is fishing for trout in other local water bodies. The reason for the poor catch record from the Strontian is actually attributed to the fact that the river is largely inaccessible to salmon unless there has been a heavy spate and as tourists are typically those who fish in this area, these spates usually occur outside the main tourist season. In addition, as across all of Scotland, there have been fewer fish returning to such local rivers reducing the potential number of fish that could be caught.
However, the main point of the original commentary was how the information provided about wild fisheries is not always reliable. This was very much the case here because a former member of the now defunct angling club has confirmed that he is 99.99% sure that the catches shown in the image are not from the River Strontian at all but a different river completely. Here is yet another example of misinformation being used to attack the salmon farming industry.
Job opportunity: It seems that Andrew Graham Stewart of Salmon & Trout Scotland is looking to boost his capability to fight the evils of salmon farming by recruiting a full-time farmed salmon campaign manager on a three-year contract. This would suggest that their aspirations are low if they expect the job to last at least three years.
The job involves targeting businesses and key influencers in the restaurant and hospitality sector with the aim of increasing public awareness and public debate about the impacts of salmon farming. I, for one, would certainly welcome increased debate with S&TC but in my experience, they are unwilling to engage in any debate at all unless it is with people who agree with them.
S&TC have recently recruited another employee, Tanglewest Douglas – a campaigners research officer, who is fresh out of university. It seems her first task was to write a 73-page review of the impacts of salmon farming, which no doubt S&TC will tout as proof of salmon farming’s negative impact on wild fish. I will be interested to see whether Ms West is happy to discuss her findings with the salmon farming sector or is it to be used as part of their campaign to try to influence the hospitality sector to avoid serving farmed salmon.
Given all the issues raised in the Scottish wild salmon strategy, it is a shame that S&TC haven’t recruited someone to promote habitat restoration, dam removal or even educate their members about zero impact handling of the fish they catch.
Wild Scottish salmon strategy: In her introduction to the Scottish Wild Salmon Strategy, The Cabinet Secretary writes that ‘there is sadly now unequivocal evidence that populations of Atlantic salmon are at crisis point’. Yet section 6, titled ‘Building an evidence base through co-ordinated scientific research and monitoring’ seems to suggest that more evidence is required. The Strategy states that the Marine Scotland Science research programme will provide crucial evidence for policy development at national scale and management action at local level. How much more research is required before action is taken to safeguard the future of wild salmon, especially as the Cabinet Secretary has highlighted that there is already unequivocal evidence that wild salmon are in trouble.
The Strategy document begins with a brief review of Scotland’s wild salmon featuring two graphs. The first shows the decline of salmon returning to Scotland’s rivers since 1971 and this alone should have caused alarm bells to be ringing thirty years ago, if not fifty. Certainly, as the number of returning fish approached the estimated number of spawning stock, even alarm bells may not have been enough. Yet, it seems very little was done to halt the decline. Even in 2017, when Prince Charles highlighted the issue at the Atlantic Salmon Trust’s 50th Anniversary Dinner by saying that in the 1980s, one in four salmon made it back to spawn and now it is one in twenty. That was over five years ago and except to plant a few trees, there seems to have been little decisive action.
The reasons why are not difficult to see. The second graph shows the salmon rod catch which increased from the 1950s to 2010. Rod catch alone is clearly not the cause of the decline, but the increasing rod catch lulled fisheries managers into a false sense of security. The fishing was good and therefore there was no need for any action, except to control those pesky salmon farms in the west. As a result, there was no pressure on the Scottish Government and their scientists to act until, things started to go wrong in 2011.
It is interesting that MSS have provided two graphs to explain the current situation for salmon. It is only when the two graphs are combined, that the message from before 2010 is apparent.
The strategy document explains that the increased number of rod-caught salmon is due in part to a combination of a reduction in commercial net fisheries and increased catch and release. The buffering effect of these measures has ensured that the spawning stock has been relatively unchanged but that this buffering capacity has been fully utilised. However, this is simply an excuse to prevent the introduction of stringent measures to control angling.
The writing was on the wall as by the late 1980s, the impact of the declining number of returning fish became apparent on the west coast where small spate rivers held only small stocks of salmon. The impact of fewer returning fish caused a collapse in the overall stock. However, anglers blamed this collapse on salmon farms and pushed MSS for research to support their claims. Despite spending millions of pounds on this research, no conclusive proof has ever been forthcoming, even though the same pattern of collapse has now occurred in east coast rivers. These much larger rivers held a greater reservoir of fish and just like the west in the 1980s, the rest of Scotland’s salmon catch collapsed after 2010. The lack of hard evidence against salmon farming has not proved a barrier to changing the thirty years plus narrative against salmon farming, even though salmon farming is totally absent from the east coast.
Section 6 of the strategy highlights that recent research has focused on stock assessments, aspects of climate change, and aquaculture production, none of which address the fundamental issue as to why fewer salmon are returning to Scotland’s shores.
They also say that historically, there has been research to gain a better understanding of predators, dams, water discharge, habitat quality and invasive species. This covers most of the ‘pressures’, yet there has still been a lack of decisive action.
Although not the main reason why salmon are in decline, the policy on Conservation Limits appears to be an example of allowing protection of fisheries to take preference over protection of the fish. In 2015/2016 MSS introduced Conservation Limits for the 109 fishery districts in Scotland. The Cabinet Secretary pointed out in her introduction to the Strategy the importance of salmon to Scotland and hence the introduction of CLs is clearly an important measure in the protection of these fish. However, England and Wales put their Conservation Limits in place in 1996, nearly twenty years before Scotland. Scottish scientists clearly dragged their feet on this issue, despite constant reminders from NASCO.
Having launched Conservation Limits, there was a flood of complaints from anglers saying that their specific river was not comparable with the classifications awarded by MSS. Rather than enforce their decision, MSS have extended the number to include a further 64 areas out-with the fisheries district system. This is potentially damaging to the efforts to protect salmon in favour of the interests of the anglers. Conservation Limits should either be applied to every single river or restricted to the established fishery districts. It should not be altered to meet the desires of anglers.
However, Conservation Limits are just a remedial measure. They don’t address the fundamental issue as to why the number of salmon returning to Scottish waters has declined. The view from the angling sector, supported by MSS, seems to be that ascertaining what happens in the marine environment is far beyond their capability and thus the focus on areas over which they can have an influence and thus efforts have been focused on salmon farming.
However, from 2005 on, anglers noticed that returning grilse were often in poor condition, referred to as skinny grilse, a condition thought to have been due to changes to or around the feeding grounds, although poor condition and early maturation do not appear to go hand in hand. Yet, skinny grilse remained just an observation, reinforcing the view that more had to be done in the freshwater environment to improve the salmon’s start in life. In recent years, there has been little mention of skinny grilse and thus is no longer considered an issue.
Although the strategy does not mention skinny grilse, it does suggest that the reduced growth at sea may have cause a decline in body size of returning salmon. Without data, it could be that such changes reflect the changing cycle of grilse domination of the total stock.
Although the wild fish sector appears to believe that dealing with issues within the marine environment is outside their capability, together with the view that if there are changes at sea, they are likely to be climate change related and therefore definitely outside their capability, at least two different scenarios have been proposed that may have impacted on the number of returning salmon, but these have been dismissed or not considered by MSS.
- Oil industry
The changes to salmon stock appear to have coincided with the development of the North Sea/Norwegian Sea oil industry. The drilling for oil may not have had any direct impact but as part of the process, continuous seismic survey work continues even to this day. This involves repeatedly detonating seismic guns towed behind survey vessels. The impact of these guns in marine mammals is well understood, which is why all vessels are required to carry observers who can interrupt the survey. There is also some understanding of damage to marine fish from these detonations, but no work has been conducted on salmon, especially in relation to the potential to disrupt the fish’s magnetic navigation system. It is possible returning salmon fail to make landfall at all and are lost at sea. Obviously, any confirmed impacts could help regulate the future operation of seismic surveying. As there is no interest from the scientific community, the continuous detonations could be still influencing the migrating patterns of the remaining salmon stock.
Sometime ago, ICES changed the way they monitor stocks of pelagic fish such as mackerel. There is a view that consequently, ICES have over recent years failed to notice that the mackerel stock in northern waters has grown out of proportion. Observations have identified excessively large individuals within massive shoals of the fish. The hypothesis proposed is that these fish are eating everything in sight including their own young and small salmon. This may help explain why salmon now returning to Scottish waters are healthy and large, suggesting that if they can avoid being predated on, they can grow well. Small fish now rarely survive.
The theory proposed is that if ICES would recognise the size of this stock, it could be significantly exploited benefiting commercial fishermen but also reducing predation pressure on migrating salmon. Seemingly, the authorities in Scotland and Norway have dismissed this hypothesis or the size of the stock.
I will continue the discussion about the wild salmon strategy in the next issue of reLAKSation.