The long standing issues of sea lice infestations on farmed salmon have reached epidemic proportions. The use of natural cleaners species is an attractive option – relative to the use of chemical treatments – but is has given rise to this new fishery for live wrasse in the south-west.

John Hepburn has kindly produced this note. 

Catching wrasse in the South West for the Scottish Salmon Farms

John Hepburn

mewstone.enterprises@gmail.com    Feb 15^th 2017

Wrasse as cleaner fish in Scottish salmon farms may be a welcome alternative to the use of chemicals to deal with sea lice. However, how the wrasse are sourced is causing concern in The South West. Breeding wrasse in captivity offers a low impact solution, but in spite of some reports suggesting the problems (eg captive-bred wrasse may prefer to eat fish food rather than lice) have been ironed out, breeders are still using wild-caught wrasse. And not just local wrasse. In 2016 fishers in Devon and Cornwall were contracted to catch ballan, corkwing, rock cook and goldsinny, with ballan wrasse being the most sought after (and valuable). The fish were caught in pots and kept alive for eventual road transport to Scotland. With the onset of winter, when the fish may migrate to deeper water and the weather is too much for the lightweight pots, the fishery is suspended.

Devon and Severn, and Cornwall IFCAs are considering what management measures should be taken should there be a call for the fishery to resume in 2017.

More work is needed to determine whether targeting wrasse in the West Country so soon after starting using wild caught local wrasse means that the Scottish populations, which some believe were less abundant than in the South West anyway, have already been significantly depleted. The wrasse species targeted by this fishery are key elements of the ecosystem as predators on a wide variety of invertebrates and as food for larger animals including diving birds and seals. An example is their importance in preying on sea urchins and maintaining vital kelp forests. Wrasse also have a very important role in removing parasites from other fish, which is of course why they are being targeted. The timing of the fishery means that nest guarding males will be removed during the breeding season reducing numbers of juveniles joining the population. If the survival rates of those caught are low, there will be increased demand, further exacerbating the impact.

Wembury MCA Advisory Group has suggested to Natural England that a precautionary approach is appropriate given that there is no certainty of a low impact, particularly in an SAC, and that it should act a stimulus for the economical captive rearing of cleaner fish to be developed more rapidly.

Natural England has replied that both locally and nationally, they and the Inshore Fisheries and Conservation Authorities (IFCAs) are working together to engage the salmon producers in order to devise management measures that will protect wrasse from over exploitation in the short term, while developing a longer term evidence based management plan that includes managing wrasse fishing within MPAs.

Addressing the concern of shifting the problem from Scotland to other parts of the UK, they are now working with Natural Resources Wales and Scottish Natural Heritage to share information and develop a joined up approach to sustainably manage this fishery in each respective country and to get the short term management in place before the next season commences in March/April.

John Hepburn:  01752 863764   07974 213301   Skype:  john.hepburn1@JohnMewstone