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Open Seas

Sustainability in Scotland's Seas

Cleaning up the ‘cleaner fish’

Wrasse are beautiful, charismatic fish that play a key role in the ecosystems of Scottish inshore waters. However, as Scottish salmon farmers now look to ‘cleaner fish’ as a way to address the industry’s sea lice problem, rising commercial demand is having potentially catastrophic impacts on wild stocks of wrasse. We take a look at the issue, find out what we know, what we don’t know and what we really should know about the environmental costs of the unprecedented demand for ‘cleaner fish.’ Our research indicates there is a systemic flaw in current fisheries management, which has failed to take precautionary steps to regulate this new fishery.

 

The sea lice problem

A big commercial concern for salmon farmers is sea lice: natural parasites that biologically weaken the health of salmon by feeding on their flesh and also transmit pathogens which affect growth rates and survival. They can therefore decimate farmed salmon harvest rates. The rising costs for health treatments then affect the cost of farming, estimated to be £30 million annually. Crucially, aside from being just a business challenge for salmon farming companies, the problem spills out beyond the open net salmon cages into the sea.

For years, the salmon farming industry has been trying to deal with lice using chemical therapeutants, vaccines and disinfectants, but unsurprisingly chemical treatments aren’t a hit with consumers – and they aren’t particularly good for the environment either. In recent years, the situation has slowly come to greater public attention, and the industry, following pressure from regulators and campaigners, notably Salmon and Trout Conservation Scotland, recognised the need to stop or reduce the discharge of hydrogen peroxide and other treatments into our sea lochs.

 

Cue ‘cleaner fish’

‘Cleaner fish’ are species of fish that feed on lice, so-named because they ‘clean’ lice-infested salmon. In recent years salmon farm companies have tried to solve the problem by putting these cleaner fish in the net cages with salmon as they are being reared. The industrial use of cleaner fish is a relatively new phenomenon and the industry is trialling the use of a variety of ‘cleaner fish’ species, wrasse (of which there are many species: cuckoo, ballan, corkwing, goldsinny, and rock cook) and lumpsuckers. Certain species are more suited to cold-water climates, while others perform better in warmer temperatures; and due to these seasonal variations, the farming regimes required to deploy this ‘biological control’ are complex. For the purposes of this analysis we focus on the use of wrasse. The industry plans to farm these fish as part of their production model, but this is experimental and they are nowhere near meeting their own demand. In the meantime, the industry is buying large numbers of wild-caught wrasse, thereby inadvertently developing a fishery that simply did not exist a few years ago.

Wrasse are beautiful, resourceful and slow-growing species. With thick lips – and sometimes tough beaks – they feed on bivalve molluscs such as limpets, mussels and scallops as well as crustacea in weedy, rocky inshore areas. But it is their unusual breeding cycle that makes them particularly unsuited to intensive fishing; all wrasse are born female and will not reach sexual maturity until they are around six years old. It’s at this point when half of wrasse will transform into males – breeding can therefore only take place when these males mature. This slow maturity makes them particularly vulnerable to overfishing, and particularly slow to recover from it when it does occur.

Unfortunately these slow-growing species are now being fished intensively, and probably unsustainably, from the wild to supply companies such as Marine Harvest and Scottish Sea Farms. There are reports that some fishermen have retired early on the back of the profits that can be made from fishing wrasse.

Rising demand

The demand is so high that Scottish salmon farmers are seemingly unable to satisfy it from Scottish waters, and are now sourcing live fish from the South coast of England. However, unlike in Scotland, where the regulators have failed to take any kind of precautionary approach to this emerging fishery, the expansion on the south coast rightly and quickly prompted serious concerns about its viability. Local regulators – in this case the Devon and Severn Inshore Fisheries Conservation Authority IFCA – have taken stringent steps to manage the fishery, imposing minimum landing sizes, seasonal closures and voluntary spatial closures to ensure sustainability of the stocks. Unfortunately no such precautionary steps have been taken in Scotland. Meanwhile salmon companies are continuing to recruit Scottish fishermen to supply wrasse to meet their demand.

Another one of the more systemic problems in Scotland is the inadequacy of public data on the subject. Not only is there no fishery management plan for the Scottish wrasse fishery, the Scottish Government does not even hold information about the numbers of wild wrasse or lumpsuckers despatched for use in salmon farms. Nor does it publish data about what happens to those fish before and after their ‘use’ as cleaner fish. We have taken the step of submitting a Freedom of Information request to establish this.

So in short, we have a cocktail of problems: the underlying problem of sea lice in the first place, the likely overfishing of wild fish to solve this problem; the fact that some regulators and fishery managers have been slow to act; and the apparent industry reluctance to disclose the environmental data they hold.

 

What we know

Scottish salmon farmers have been trying to farm cleaner fish since 2012 with limited success. Three years after they started, the Scottish Government started recording data on the fishery. In 2015, Government reported that Scottish fish farmers produced 235,000 lumpsuckers and 75,000 wrasse (just over 300,000 cleaner fish in total). In 2016, this was 262,000 and 118,000 respectively. Salmon farms have possibly been importing extra farmed cleaner fish given that the  Scottish Government stated:“we understand that 1.5 million farmed cleaner fish were utilised by the aquaculture sector in Scotland in 2016.” Other figures reported recently in the trade press, indicate that Scottish-based fish farms currently “have the capacity” to produce in excess of 2 million cleaner fish (1.1 million via Marine Harvest, 900,000 via Scottish Salmon Company as well as other farming initiatives), though do not declare how much of each species.

Unfortunately, as mentioned, the salmon farming  industry has been ‘utilising’ a lot more fish than those it farms. In a reactive statement to the press the SSPO – the Scottish salmon farmers trade body – says that “around half of the wrasse we use is farmed and the rest is caught.” If we assume that wrasse farming as a proportion of total cleaner fish farming has remained roughly the same through time (ie 32% of all farmed cleaner fish), then the industry would have been using approximately 480,000 farmed wrasse in 2016. If the industry is using “around half” farmed and wild-caught wrasse, then the industry was possibly using similar numbers of wild caught wrasse in 2016, ie around 480,000.

Oddly this doesn’t tally with official figures. We checked this against Fisheries Statistics published by the MMO. In 2015, 89 tonnes of wild-wrasse were caught. In 2016 this figure was 60 tonnes . We conservatively estimate that 480,000 wrasse caught from the wild would weigh around 217 tonnes (i.e. 1lb per fish, on the assumption that ballan wrasse weigh on average 1-3lbs and other wrasse are less than 1lb).

So it’s not entirely clear what’s going on, these figures don’t stack up and there is no way of verifying through public catch data what is happening. What is clear is that the value of wild-caught wrasse is high, commanding a premium that has incentivised the rapid growth of a fishery before any management safeguards for the Scottish fishery have been put in place.

 

Norwegian direction?

When it comes to fish farming, the situation in Norway usually demonstrates the direction of travel – particularly given many of the companies operating in Scotland are Norwegian-owned. The Norwegian industry has really taken to cleaner fish and aims to be using 40 million cleaner fish each year by 2020 but, just as in Scotland, they also use wild-caught fish. Of the 16.4 million cleaner fish (wrasse and lumpsuckers) used in 2015, 57% of these were farmed, yet the world’s biggest salmon farm company, Marine Harvest, aims to be self-sufficient and independent of wild-caught cleaner fish by next year!

As the demand for cleaner fish soars, with an estimated 10 million needed in the UK by 2020 , the Scottish industry still looks to be a long way off achieving this figure and therefore their current reliance on a wild fishery will likely persist for the foreseeable future.

 

What we don’t know

In Rumsfeldian terms, there are a lot of ‘known unknowns’, and most specifically: what impacts this fishery is having on the wild population of wrasse in Scottish (and English) waters. One of the few questions that the Scottish Government was able to definitively answer was their own lack of understanding. “We have not undertaken any research on the impact wrasse fishing in Scotland may have had on wrasse stocks and sustainability.” This means that the fishery for wrasse is being licensed (and promoted?) by a government that have no idea how many fish there are in the sea, no idea what a safe level of fishing would be, and no idea whether the level that is going on is in excess of this. This fails not only government policy, but also fisheries law and the principles of the CFP.

The issue of the poor-to-non-existent management of the wrasse fishery was flagged as early as 2014 via the then Inshore Fisheries Groups, but there is still no action. Organisations like the Scottish Wildlife Trust and the Wester Ross Fishery Trust have tried diplomatically to resolve this worrying blind spot, but meetings with the fish farming industry have not yielded much in the way of action, with no public sign of industry-government talks progressing.  How can a new fishery develop so quickly without any management oversight? The situation, we contend, highlights not just a possible crisis for wrasse stocks, but a more systemic problem in the way Scotland manages its seas, specifically that managers do not take a precautionary approach to fisheries, and permit practices before they have studied them and without collecting proper evidence.

There are a host of questions that need answered before wrasse fishing and even the use of farmed cleaner can be considered sustainable.

 

Experimental and unresolved

Cleaner fish mortalities in salmon farms are often high, and very few cleaner fish survive through a full salmon production cycle. Mortality is often related to infectious diseases, most commonly caused by bacterial agents. Although cases of Viral Haemorrhagic Septicaemia (VHS) have been observed in both lumpfish and wrasse, they are not currently listed as a VHS-susceptible species and indeed they can be a vector for this disease.

Furthermore, cleaner fish themselves are actually prone to sea lice (Caligidae elongatus). Whilst some studies state that there isn’t any evidence that lumpsuckers are vulnerable to the more problematic ‘salmon louse’ (Lepeophtheirus salmonis), other studies would indicate that wrasse or lumpfish do play host to the salmon louse. Aquaculture scientists have also identified a whole host of as yet unresolved fish husbandry issues for lumpsuckers.

Farmed wrasse are also escaping. Over 1,000 fish escaped due to human error in March at a farm site off the coast of Mull. Whilst there is now long overdue research planned for assessing the genetic introgression of farmed salmonids within the wild stock, no such studies are in the pipeline for farmed wrasse or lumpsuckers. Given the industry is researching how to breed certain qualities into farmed cleaner fish, the risk of genetic introgression is real.

 

Solutions

The consumer and policy-makers need more information. The Scottish Government should start gathering and publishing data not just on the numbers of farmed cleaner fish produced by Scottish aquaculture companies, but also the number of wild fish transferred to and used by salmon farms. This information is held by salmon farms and is available to the Scottish Government when conducting to official inspection of farms. There is no reason why this information should not be routinely reported, aggregated and held by Marine Scotland, the public authority responsible for regulating activities in our marine environment. Indeed it should be integrated with wild fisheries catch data that is published in annual catch statistics. Coupled with stock assessments, this would enable fisheries managers to better understand trends within the fishery and implement precautionary controls to ensure the sustainability of the stock.

In the meantime, salmon companies should also, as part of their corporate social and environmental responsibility reports, publish key data on their use of wild fish as cleaner fish. This should include specifically, how many have been purchased and from what fisheries (eg English or Scottish, or regional), so that consumers can make judgements about whether or not they are eating salmon reared using cleaner fish sourced from well-managed fisheries.

The Scottish Parliament has recently announced a Parliamentary inquiry into salmon farming (prompted in large part by the Salmon and Trout Conservation Scotland’s public petition about the impacts of sea lice). Whilst the ‘cleaner fish’ situation is undoubtedly inextricably linked to the wider sustainability concerns around the business model of open net cage salmon farming in Scotland, there are tools to deal with the concerns about the wild wrasse fishery now.

We need to stop intensively fishing for wrasse until we have established the health of Scottish populations of wrasse, at a meaningful stock-specific level. Fisheries interests, and the Scottish Wildlife Trust have called for no-catch zones for wrasse to protect populations. Others are calling for a moratorium on the fishery until stock assessments have been undertaken and a management plan is in place. The Scottish Government need to take urgent action to i. understand the status of wrasse in Scotland, ii. understand the biological limits of that stock, i.e. what scale of fishery could permitted, iii. Set up a fisheries management regime to restrict the number of fish caught by wrasse fishermen to be within this limit. The salmon farming industry should also take a role in this, given they are the end user, and by proxy are risking the sustainability of their own product.

Scottish government have apparently approached this situation blind, without any form of precautionary approach to management. The result has been to dirty our seas with an unsustainable cleanerfish fishery. It’s time to come clean.