Major milestone achieved in sea lice control

A pair of Scotland’s leading salmon farmers have reported a ‘breakthrough’ in the drive to control sea lice. Marine Harvest Scotland and Scottish Sea Farms have been working with the Institute of Aquaculture at the University of Stirling to produce farm-reared ‘cleaner fish’, so-called because they eat naturally occurring external parasites such as sea lice from salmon. The aim was to rear the cleaner fish in the most responsible, sustainable and environmentally-friendly way. In six years, the project team has bred wild-caught Ballan wrasse (Labrus bergylta) and raised the offspring from egg to adults of reproductive age. In what is believed to be a world first, those same offspring have produced their own eggs, which have successfully hatched, completing the life cycle of farming wrasse in a controlled environment. The team has also gone on to successfully wean the wrasse larvae and fry from live food to a dry diet – another key milestone and one that will give salmon farmers more control over the health and nutrition of farmed wrasse. It is the sector’s ambition to become self-sustaining and use only farmed stocks of cleaner fish – a goal that is now within grasp thanks to these latest advances. Says Marine Harvest Scotland’s hatchery manager Paul Featherstone said: ‘Ballan wrasse provide highly effective, highly natural sea lice control and as such is in huge demand. ‘With this breakthrough, we now have proven procedures for breeding, weaning and rearing wrasse.’ Adds Scottish Sea Farms’ head of fish health, Ralph Bickerdike: ‘These landmark breakthroughs are the result of many years of collaborative research.’ The two leading salmon farmers entered into the multi-million pound collaboration in 2011. Under the terms of the collaboration, all insights gleaned will be shared with the wider sector for the common good.