Sea lice are a costly problem for the salmon farming industry, with annual losses exceeding £700 million.
New research funded by the Norwegian Seafood Research Fund (FHF) is offering a glimpse of a potential breakthrough in the fight against sea lice.
The study, recently published in BMC Biology, has uncovered how coho salmon, native to the Pacific, naturally fend off sea lice, thanks to a powerful skin reaction that forces the parasites to detach before they can cause harm.
Unlike Atlantic salmon, which are highly susceptible to sea lice, coho salmon possess a unique response in their skin cells, known as epithelial hyperplasia. This reaction causes the skin to thicken and swell, effectively ejecting the lice within a short period.
Researchers have identified key genes involved in this process, opening the door to the possibility of using gene editing to give Atlantic salmon the same lice-fighting abilities.
In the study, Atlantic salmon eggs were donated by Benchmark Genetics Iceland, representing a commercial strain with less than average breeding values for sea lice resistance, to closely mirror the resistance levels found in natural populations prior to selective breeding.
Coho salmon, on the other hand, were provided by the Quinsam River Hatchery in British Columbia, Canada, using wild-caught specimens.
Both species were reared under controlled conditions in a Recirculating Aquaculture System at the Center for Aquaculture Technologies on Prince Edward Island, Canada. The fish were carefully monitored, and during the experiment, they were exposed to locally sourced sea lice (Lepeophtheirus salmonis copepodids).
Samples were taken at regular intervals to assess the response of both species to sea lice attachment, with a particular focus on the skin and pelvic fin tissues. This comprehensive setup allowed the researchers to closely examine the differences in sea lice resistance mechanisms between Atlantic and Coho salmon.
Current methods to control these parasites, including chemical treatments, are becoming less effective and raise environmental concerns. If gene editing can replicate the coho salmon’s natural resistance in Atlantic salmon, it could significantly reduce the industry’s reliance on these treatments, leading to lower costs, improved sustainability, and better fish welfare.
