Why we care about cleaner fish

Here at OneKind we have always promoted the welfare of fish, whether they are wild-caught, farmed or used in the pet trade. Since August this year, we have been campaigning for better fish welfare on salmon farms in Scotland, and earlier this week we furthered our campaign by releasing a new report Cleaner fish welfare on Scotland’s salmon farms.

We chose to focus on these fish as their welfare is often forgotten about or perhaps ignored, but should not be any less important than that of farmed salmon, after all they are sentient beings, capable of feeling pain and suffering. But what are cleaner fish, and what problems do they face on salmon farms in Scotland?

What are cleaner fish?

Cleaner fish (primarily ballan wrasse and lumpsucker) are placed into salmon cages to eat sea lice, which are parasites that can cause severe problems to infected salmon. Whilst this may, on the surface, sound like a solution to the sea lice problem, currently, we believe that the use of cleaner fish brings welfare challenges. Worryingly, it is not fully known  to what extent, both ballan wrasse and lumpsucker, actually perform cleaning behaviour in the wild. They are not like tropical species of cleaner fish, such as the bluestreak cleaner wrasse, which must perform cleaning behaviour to obtain an adequate source of food, instead lumpsuckers and wrasse are more opportunistic- and may eat a couple of sea lice in the wild. Incredibly in 2016, 1.5 million farmed cleaner fish were used on salmon farms in Scotland, and this is expected to rise rapidly, with predictions that 10 million cleaner fish will be required by the UK in 2020.

Welfare problems

Because the use of cleaner fish on salmon farms in Scotland is a relatively new concept, there are a lot of unknowns about their behaviour and welfare in captivity, and there is a lack of data collected and published on cleaner fish, with Marine Scotland stating that they have “insufficient data” on things including cleaner fish survival rates, and causes of mortalities. Also, whilst there are some mentions of cleaner fish in various accreditation schemes (such as RSPCA Assured and the Code of Good Practice) these are not detailed, and do not account for species-specific differences.

We do know that supplementary feeding is necessary for cleaner fish welfare, as cleaner fish cannot obtain all the correct nutrients they need from sea lice they pick off the skin of salmon. Shelters too need to be provided to cleaner fish, in the wild ballan wrasse shelter in rocks overnight, and lumpsuckers need them as they require surfaces to stick too (hence the name!).

There are also numerous health problems that cleaner fish can face on salmon farms. They can suffer from amoebic gill disease, fungal infections, and somewhat ironically, lumpsuckers can be parasitized by sea lice. There is even suggestion that cleaner fish can spread pathogens to salmon, for example scientists have reported that lumpsuckers are carriers of the parasite that causes amoebic gill disease, which could potentially spread to salmon.

There are also problems with the interactions between salmon and cleaner fish. Salmon are carnivorous, so have been shown to attack, and eat, cleaner fish. Wrasse can also be aggressive to salmon, with incidents where they have picked at the eyes of salmon, which led to salmon dying, and lumpsuckers can compete with salmon for access to salmon food.

Overall, it has been show that the mortality rates of cleaner fish can be high in salmon cages – with evidence showing that often very few survive the salmon production cycle of 18 months (despite their natural lifespan of up to 9-14 years for lumpsuckers, and 29 years for ballan wrasse). Some instances of high mortality rates on salmon farms in Scotland include an incident in 2017 where at the salmon farm North Shore, freshwater treatment for sea lice killed nearly 100% of the lumpsuckers held on site. Another example is that at the farm Loch Alsh (Sron), approximately 40% of the cleaner fish on site died, in one incident in 2017, as a result of amoebic gill disease.

What are OneKind doing?

Despite the welfare issues that face cleaner fish (as well as farmed salmon and wildlife), the salmon farming industry in Scotland is committed to doubling salmon farming production by 2030. We believe that such expansion without tackling key welfare issues will seriously compromise the welfare of farmed fish, cleaner fish, and wildlife. That is why we are calling for a moratorium on salmon farming expansion plans, until key welfare issues are addressed.

We also don’t want cleaner fish welfare to be forgotten about- and we believe that there are welfare issues that urgently need to be addressed. That is why we are calling for:

• A moratorium on the use of cleaner fish, until welfare issues are addressed
• Increased research on cleaner fish welfare
• Development of detailed welfare standards for cleaner fish
• Publication of data on numbers of cleaner fish used, and survival rates

What can you do?

1. If you want to learn more about the welfare of cleaner fish on salmon farms, then check out our new report!
2. Sign our salmon farming petition, which calls for a moratorium on proposed industry expansion plans, until animal welfare (including cleaner fish welfare!) is safeguarded.
3. Donate to our campaign, or become a member, so that we can continue to give all of Scotland’s animals- including cleaner fish- a louder voice!