‘Breakthrough’ claimed in sea lice control
Two Scottish salmon farming businesses have reported a ‘major breakthrough’ in research 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 farmreared ‘cleaner fish’, so-called because they eat naturally occurring parasites including sea lice from salmon.
Over six years, the project team has bred wild-caught Ballan wrasse (Labrus bergylta) and raised the offspring from egg to adults of reproductive age.
Now, in what is believed to be a world first, those offspring have produced their own eggs, which have successfully hatched, completing the life cycle of farming wrasse in a controlled environment.
The team has gone on to successfully wean the wrasse larvae and fry from live food to a dry diet – another milestone that will give salmon farmers more control over the health and nutrition of farmed wrasse.
In the longer term, it is hoped the breakthrough will help meet the growing demand for cleaner fish as Scotland’s salmon farmers seek to control sea lice through non-medicinal, environmentally-friendly approaches.
Currently, the majority of wrasse used as cleaner fish are wild-caught in accordance with guidelines specified by Marine Scotland, RSPCA Assured and local fishery boards to ensure it is done sustainably.
However, 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 advances.
Marine Harvest Scotland hatchery manager Paul Featherstone said: ‘Ballan wrasse provides highly effective, highly natural sea lice control. With this breakthrough, we now have proven procedures for breeding, weaning and rearing wrasse, which will both help ensure farmers have a more secure, controllable supply and reduce reliance on wild stocks.’
Scottish Sea Farms head of fish health Ralph Bickerdike added: ‘These landmark breakthroughs are the result of many years of collaborative research, involving a significant investment of time and money by farmers and academic partners intent on developing natural solutions to the control of sea lice.’