CLEANER WRASSE DELIVER BOOST FOR WESTER ROSS FISHERIES
Cleaner wrasse deliver boost for Wester Ross Fisheries. As we peered into the fish pen at the Wester Ross Fisheries Ltd site at Ardmair near Ullapool on the north-west coast of Scotland, the sleek torpedo-shaped bodies of salmon flashed and glistened in the water.
All the fish were clean-skinned and healthy, not a sea louse to be seen, and site supervisor Chris Ford was justifiably proud of the stock and the care and attention that goes into looking after them.
The key to this control of the ever-present threat of sea lice is wrasse, which act as ‘cleaner fish’, naturally preying upon these skin parasites. Wrasse naturally glean crustaceans and small molluscs from kelp and rocks, and when placed in a salmon pen, they quickly take to gently picking-off sea lice from salmon.
It’s the perfect solution – no medicines are needed for sea lice control and the salmon prosper. Indeed, this natural remedy aids salmon development, because when treated with medicines to control sea lice, the salmon tend to reduce their feeding for a few days afterwards, thus slowing growth.
Wester Ross Fisheries started using wrasse about five years ago and have never looked back since, such has been their success. Chris says it has been a learning process, finding which wrasse species are best at controlling lice, the optimum stocking densities and also developing shelters for the diurnal wrasse where they can hide and rest during the night.
“We’ve also learnt the best size of wrasse for sea lice control,” says Chris. “Ballan wrasse are our favoured species, but they mustn’t be too big or too small. Goldsinny and rock cook wrasse are also very effective.”