The great Atlantic salmon is still very much an unknown quantity as far as its DNA make-up is concerned. Fewer than 100 salmon genes have yet been described, representing less than 1 per cent of the expected total number. Researchers at NUI Galway are playing a pivotal role in overcoming the absence of so much fundamental knowledge about the species.
This is so apt given that "the salmon of knowledge", an bradan feasa, plays a central part in Celtic mythology going back to the time of Fionn Mac Cumhaill, and nowadays its well-being is vital to the development and sustainability of Irish aquaculture and fisheries. Indeed, Irish scientists have been to the forefront in researching the species for many years. The research group based in NUI Galway's microbiology department is leading a £1 million EU project to identify at least 10,000 new genes from Atlantic salmon within three years. Dr Richard Powell, who heads the group, is co-ordinator of the SALGENE project, which includes partner researchers from Norway, Scotland and Denmark. His brief is to use gene-sequencing techniques to determine some 2,500 of its genes, most of which are related to sex organ tissue.
The wild Atlantic salmon is one of the more significant fish species in the northern hemisphere due to its importance spanning aquaculture, fisheries and angling. European aquaculture of Atlantic salmon and rainbow trout produces 260,000 and 180,000 tonnes annually. Similarly, several related salmonid species, including brown trout and Arctic charr, are part of significant commercial fisheries. The brown trout is a remarkably close relative of the salmon, Dr Powell confirmed, with a 95 per cent similarity in genetic make-up. If the salmon and brown trout are sisters, then the Arctic charr is their aunt.
"One of the highlights of the SALGENE project will be the completion of a salmon genome map using anonymous microsatellite genetic markers expected by the year 2000. We then expect to quickly add thousands of identified genes from the SALGENE project to this map," Dr Powell says.
This genome map, he adds, will play a vital role in salmon research, including the areas of population genetics and diversity of natural stocks. It will also improve the analysis of brood stocks in aquaculture, including the identification of genes responsible for selected quantitative traits.
The salmon stocks used in aquaculture have, due to selective breeding programmes, become appreciably different from their wild counterparts. Dr Powell says genetics will play an increasingly important role in achieving further improvements in the performance of these brood stocks.
Traits that may be amenable to genetic improvement include growth, late maturity, disease resistance, flesh quality, pigment uptake and temperature tolerance. Also, in terms of fisheries and angling, more research tools are required to document and describe the diversity and health of natural stocks, aiding their conservation.
By identifying 10,000 salmon genes from eight tissue types (which in turn will contain many more cell types), the SALGENE project will provide an important "bioinformatic resource". By selecting liver tissue, for example, it will include a huge diversity of cell types. The resulting map will be the largest genetic resource for a commercially significant fish species group, Dr Powell says.
He is particularly happy that the Irish reputation for good science when it comes to the salmon is about to be extended, with their participation in a new and exciting "genomic phase" of work on the species.