Salmon now more resistant to sea lice infestations

Christian Pérez The genetic markers have already been used to screen broodstock selected in 2012 and have been introduced to the company’s egg production this year, ensuring the next generation of farmed salmon is more resistant to the parasites. According to the information published by the company, Landcatch was the first aquaculture company to pinpoint genes controlling the susceptibility of salmon to Infectious Pancreatic Necrosis (IPN). As part of a strategy to improve robustness, the firm’s scientists also proved that sea lice resistance is inherited and produced more resistant juvenile fish and eggs. Neil Manchester, Managing Director of Landcatch, said: “We have located a major gene - or Quantitative Trait Loci (QTL) - controlling resistance to sea lice. This is mapped using variations in DNA sequences, or Single Nucleotide Polymorphisms (SNPs), which act as biological markers and help scientists identify individual salmon that are more robust for breeding and egg production in Europe and Chile. “This is a significant milestone for Landcatch and the aquaculture industry. This is available now, and the fact that we’ve achieved this breakthrough a year ahead of schedule is to be welcomed. “Many thought it would be another decade to get this far, so we are proud to be at the cutting edge and this far ahead in an important area for the industry.” Dr Alan Tinch, Director of Genetics at Landcatch, said, the latest discovery is another important advance in the development of more robust farmed salmon. “Genetic markers and genomic selection using the Landcatch SNP Chip for sea lice resistance are major steps forward in developing a sustainable improvement in sea lice resistance with resulting improvement in the welfare and performance of Landcatch Atlantic salmon. “It will allow us to accurately pick out resistant broodstock for breeding, giving sustainable improvement in sea lice resistance. The resulting salmon have better welfare and perform better than previous generations. “Our genetic strategy is to improve disease resistance in salmon and sea lice resistance is a core part of this. Genetic resistance will act alongside advances in husbandry, nutrition and medical treatment to reduce the thorny problem of sea lice.” Samples from the Landcatch breeding programmes in Chile are also being screened to determine if the major gene is also effective against the Chilean form of sea lice. Dr Tinch added: “The species of sea lice are different in Europe and Chile but the discovery we made in Scottish salmon may still apply because Atlantic salmon  around the world share the same origins.   “Whether we see the same effect in Chile or not will be interesting and help significantly in our understanding of the biology of sea lice infestation.”