Parasite lost as science tackles sea lice menace

The aquaculture industry has moved closer to its ‘Holy Grail’ due to a major scientific breakthrough by a Scottish company.

Farmed salmon have been made more resistant to the menace of sea lice by Scottish leaders in the field, Landcatch.

The company’s genetics experts have pinpointed a major gene that controls how susceptible individual fish are to sea lice infestation.

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.

Sea lice are one of the long-term challenges facing the aquaculture industry and affect production across the world. Genetics is set to play a key role in tackling the issue, along with advances in husbandry, nutrition and medical treatments.

Landcatch, which has its headquarters in Ormsary in Argyll and a five-strong genetics team based at Stirling University Innovation Park, is pioneering work in the development of genetic and genomic tools for improving farmed salmon.

Genomic technology uses information from DNA to better understand inherited traits and predict performance of individual animals

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.”

Landcatch is at the forefront of genomic research developing new markers for important traits. In collaboration with researchers in Scotland and the biotechnology company Affymetrix, it has developed a high density SNP Chip - glass slides used to analyse SNPs which act as biological markers and help scientists improve the accuracy of genetic predictions of resistance to disease and other commercially important traits.

Dr Alan Tinch, director of genetics, 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 enhancement of the welfare and performance of Landcatch Atlantic salmon.

“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.”

Landcatch, which is part of the global Hendrix Genetics multi-species food production organisation, supplies genetic services and Atlantic salmon eggs and smolts to the aquaculture industry. It uses selective breeding to develop strains of salmon which can perform to ever higher levels at every stage of production from eggs to adult fish.

Genomic selection using SNP Chips is already routinely applied in crops, cattle, pigs and chickens but Landcatch is the first company to apply the science to salmon. 

English: Male and female Lepeophtheirus salmonis (Photo credit: Wikipedia)