Best value: The Scottish Parliament paid £45,562 to SAMS for their report on the environmental impacts of salmon farming, however the members of the environment committee might have learnt more about the interactions between salmon farms, sea lice and wild fish by spending just £12. This would have bought them the book ‘Loch Maree’s Missing Sea Trout’.

In our view, the scientific review raised more questions than it answered. One of the views in the report was that ‘there is a gradually emerging body of evidence, from studies elsewhere, that sea lice not only have the potential to have a negative effect on wild salmon, but that in many situations this is likely to be the case’. One of the scientific papers from which the SAMS review drew its conclusion was that by Taranger et. al. (2015). This paper is interesting for a number of reasons but not least because it also features in one of the written submissions made to the parliamentary committee.

The submission from the Lochaber Fisheries Trust states that “the Norwegian government has developed a tool for assessing the impacts of aquaculture including the effect of lice burdens on wild fish (Taranger et. al. 2015). This method predicted that of the 83 sea trout we sampled near Fort William in 2017, 72% would die as a result of their lice burden”.

Two questions immediately spring to mind. Firstly, if so many of this small sample are so infested by lice that they will die, why are they still alive? And secondly, the salmon farming industry has been operating for over thirty years in the Lochaber area so given this high rate of mortality, how are there any sea trout still to be found in the area?

Of course, the simple answer is that Taranger’s paper, based on mathematical modeling and assumptions is significantly flawed. Lochaber Fisheries Trust appear to infer from their calculation that the 72% mortality of the sample is reflected in the whole population. However, sea lice are ‘overdispersed’ in the wild and so what might be observed in a small sample is not actually representative of the whole population. In addition, whilst young fish may be found to carry large numbers of juvenile lice, many of the lice do not remain on the fish. This would clearly affect any calculation of mortality.

We, at Callander McDowell, are not the only ones to think this way. The Norwegian website highlights that NRK News carried a headline that ‘Sea lice kill almost all salmon smolts’. The Institute of Marine Research had triggered an alarm after estimating a mortality of 83% in the River Opo, not far from Bergen. states that even schoolchildren with normal computation skills can work out that if mortality levels are so high, then the salmon population in the area should have died out.

Yet, whilst IMR appear to claim high mortality rates, they issued a press release at the beginning of February which states that migrating salmon smolts were probably negatively affected by sea lice. We are surprised that given their model, they can still only say that smolts were probably affect by lice. We would hope for more certainty as to whether the smolts were or were not affected.

Certainly, Lochaber Fisheries Trust submission suggests that local populations of fish are affected. A new paper by Vollset et. al. (ICES Journal of Marine Science (2018), 75(1), 50–60.) discusses the way in which population mortality is estimated.

‘In order to understand the “estimated % population mortality” we first need to decide whether to focus on overall mortality or mortality among those fish that would have survived in the absence of any sea lice. Mortality of smolts between the time they leave fresh water and the time they return to spawn is high e.g. if we assume that ocean mortality would be 95% in the absence of any sea lice exposure from fish farming, and we consider overall mortality, the worst possible effect attributable to sea lice would be 5% (i.e. lice kill all fish that would otherwise have survived). This value is commonly referred to as the “risk difference”. This apparently low level of mortality attributable to lice would, in fact, be disastrous to the population. This approach has been used to conclude that sea lice have only a small effect. We and others view this as inappropriate. No matter how many wild fish die due to salmon lice, the risk difference would never exceed 5%, and given the thresholds of 10% and 30% in the “traffic light system” the situation would always be defined as “sustainable”. This would be absurd, and would clearly violate the intentions of the rule’.

We, at Callander McDowell, belong to team ‘95%’. We are very much of the view that if 95% of migrating salmon fail to return to their home rivers, then any additional mortality due to sea lice must be of the remaining 5%. We appreciate that this is difficult to accept, especially in Norway where there is just one coast. It is therefore difficult to differentiate between farming and non-farming areas.  The Scottish experience is very different. This is because Scotland is effectively divided by two very different coasts; one to the North Sea and the other to the Atlantic. Only one of these coasts is home to salmon farming, the other, the east coast, has no salmon farms at all.

Both coasts suffer from low return rates of migrating salmon. It does seem inconceivable that fish from both coasts would experience similar rates of return but for very different reasons. If 95% of east coast fish are dying at sea, then why would mortality of fish from the west coast fish be for a different reason. The suggestion is that up to 40% of west coast fish die from sea lice leaving the remaining 60% to be exposed to the same mortality pressures as east coast fish. However, if the biggest factor affecting east coast fish is marine mortality leading to only a 5% return, then it might be expected that if the remaining 60% of west coast fish are subject to the same pressure, then they all might succumb? Given the proximity of both coasts to each other, it seems unlikely that mortality would be so different. This is why the 1% mortality due to sea lice identified by both Norwegian and Irish researchers appears to make sense. However, the authors of the Vollset paper disagree saying that if this was the case, then the risk would never exceed 5% and under current classification would always be considered sustainable. They say that this is absurd because under the Traffic Light System, there are thresholds up to 30% and having a maximum 5% mortality attributable to sea lice would violate the intentions of the rule.

We, at Callander McDowell, have contemplated this dilemma. Clearly there is a disparity between the findings of large scale smolt release studies and the Traffic Light thresholds that have been established by modelling. Perhaps Vollset and his colleagues have not considered the obvious reason for any discrepancy.  It is that the Traffic Light System is wrong.


Put out a challenge: Intrafish have been kind enough to publish an article about Martin’s book on their Norwegian site. This was followed up with comments from the Norwegian sea lice community. One leading scientist told Intrafish that it wasn’t a priority for him to read the book whilst another just said ‘no comment’.  This wasn’t surprising as we have written previously that we have found the Norwegian sea lice community rather insular and not particularly interested in anything that might contradict the existing view.

Whilst the scientific community has been reluctant to comment, Erik Sterud of Norsk Lakseelver, representing anglers, is not so shy. He told Intrafish that Martin wouldn’t get a hearing in Norway because the book is not a scientific dissertation and has not been through a scientific assessment.

So here is a challenge? We suggest that the Sea Lice Expert Group invite Martin to one of their meetings, so he can present his findings which would be then subject to scientific scrutiny. We would suggest that Erik Sterud is also in attendance. If the scientific sea lice community are so sure of their own work, then they should have nothing to fear. We always believed that science was about exchanging ideas. At the end of the day, it is not the scientific process that is important but rather the protection of stocks of wild salmon and sea trout as well as safeguarding jobs and coastal communities throughout Norway. In case the sea lice community do not read this mailing, we are sure that there are those in the salmon farming industry who would be happy to pass on our message.

We wait to hear.


Open and closed:  Fish Farming Expert report that following the news that the NIRI Farm in Scotland is up for sale, there has been interest from potential buyers from Norway, the US and Thailand. Despite the efforts to push the existing Scottish salmon industry into closed containment, none of the many Scottish exponents of such farms, appear willing to put their hands in their pockets to buy into this form of production. They are keen for others to invest but seem reluctant to do so themselves. Perhaps they are aware that this is a sure-fire way of losing their investment.

News has just broken that a second farming company is to open a closed containment farm in Maine. One anti-farming critic has tweeted that Norway is missing out by not leading the way in this new technology. We think Norwegian or any other salmon farmers are right to be cautious. Just because two companies have found sufficient investors to build new farms doesn’t mean that they will be a commercial success.

There is one small point at the end of the news story about this new farm that makes us more wary. According to Undercurrent News, the press release from Whole Oceans states that the company has presold 100% of their production for the next ten years. It’s a very brave buyer who would make such a commitment without even seeing or tasting the fish.

We heard a similar story from Fish-From in Scotland as they too said that they had presold their salmon. Presumably, the potential buyers of Fish From salmon have found another source because if they are still waiting for their presold fish, they will be having a long wait.

Whole Oceans also say that as they won’t have to ship their salmon overseas, they will be able to sell a fresher product at a higher price. We, at Callander McDowell are not convinced. We have previously heard that fish from closed containment should be able to command a higher price because it is more environmentally friendly but there is no evidence to support this view. Equally, we have also heard that consumers will pay more for fresher fish and equally, this is unproven as most consumers expect their fish to be fresh as a matter of course.

Once farms are up and running, then it can be seen whether buyers want the fish and what sort of price they are prepared to pay. Until then, any thoughts of pre-selling over ten years seems rather unrealistic.


Origin: We are conscious that our continued focus on sea lice is of little interest to those wishing to hear our views on the markets. This week we came across a photo on Twitter that sums up a long-term question we have about promoting the origin of fish and food. The photo is a picture of a menu from a high-end restaurant in Birmingham. We are sure it is very good and the food excellent. It is not so much about the food itself, but rather the way it is described.

The menu has four starters, two of which are fish and four mains, again two of which are fish. This is impressive as most restaurants would offer just one fish dish. The fish starters are prepared from mackerel and halibut, whilst the mains are turbot and cod.

The descriptions of the fish are mackerel, halibut, Cornish turbot and Skrei cod. For comparison, the other starters are Norfolk quail and carrot. The two other mains are described as Blythburgh pork and Aberdeenshire beef.

We are often told that consumers are interested in the origin of the food they eat and thus the descriptions that indicate for example, that the turbot comes from Cornwall. Yet, if consumers are interested, what about the origins of the mackerel and halibut used in the starters. Why do these fish not warrant a description of their origin? If consumers care so much, surely, these fish deserve a description too.

Yet this is typical of many restaurants when descriptions of origin appear only against some species but not others. It seems to us that if consumers are happy to eat the mackerel and halibut without knowing the origin, then why not just describe the Cornish turbot as turbot?

Before we turn to the last fish species, we should mention the Norfolk quail, the Aberdeenshire beef and the Blythburgh pork. If the similar protocol is used, then the Blythburgh pork should be labelled as Suffolk pork and this is the county where the pigs are reared. Blythburgh is actually the farm and not the location. It could be argued that if farm rather than area is important then the beef and the quail should be labelled according to who produced it rather than the geographic location.

Finally, we come back to the cod. We, who work in the industry, sometimes become too blasé about what we produce thinking that everyone else is on message too. We asked a few people about the menu and was asked ‘where is Skrei?’ Of course, in the same format as other dishes, Skrei would be expected to relate to the geographic origin. The fact that the fish is from Norway has been omitted unless the consumer knew that Skrei was cod from Norway. The dish should ideally read ‘Norwegian Skrei’ but then most British consumers don’t know what is Skrei!


Fresh or wild: Undercurrent News reports that a German testing charity has taste tested fresh and frozen farmed salmon and frozen wild salmon. They concluded that fresh farmed salmon comes out on top. They found that six out of seven samples rated good whilst for frozen salmon it was only two out of nine.

The charity concluded that the taste of wild salmon is compromised by the distances the fish has been transported and the length of time it has been frozen. By comparison eleven out of 14 samples of farmed frozen salmon were rated good and the testers concluded that the reason for the higher acceptance was that the farmed salmon had only travelled from Norway unlike the wild salmon that had come from Alaska or Russia.

Unfortunately, the full report is not available outside Germany, but the summary given on the Warrentest website does not mention a more significant difference between wild and farmed salmon than the distance it has been transported. This is that they are very different species with different eating and taste characteristics.  They are not the same fish and clearly this can impact on how they taste.