Young salmon showing variations in parr marks (Photo: S. Pedersen)
By Louis Gasparini
Wild Atlantic salmon populations have declined drastically in recent decades, but new findings by Integrative Biology researchers could help with restoration efforts for this important aquatic species.
Prof. Elizabeth Boulding and her research group made several important discoveries about Atlantic salmon genes that influence the appearance and growth of the fish, and which could have important implications for their potential restoration.
“If salmon go extinct in a stream, we now have the technology to re-introduce them,” says Boulding, noting that a better understanding of salmon genomics can help guide these efforts.
Boulding and graduate student Stephanie Pedersen set out to find areas of the salmon’s genome (called quantitative trait loci or QTL) that are associated with the size, shape, and colouration of the fish. For example, they identified QTL related to parr marks, which are the dark colouration patterns on young salmon. Parr marks can mean the difference between life and death for a small fish because they provide camouflage in rivers, making it harder for predators such as birds to spot them. The team discovered multiple new QTL that control the colour and number of parr marks.
These findings can now be used by ecologists to genetically select the best variety of salmon to re-introduce in different areas. To provide the best camouflage, parr marks must match the surrounding environment and streams can vary significantly in appearance. For example, they can be dark and muddy, or filled with light gravel. If a young salmon has parr marks that match the colour of a muddy riverbed, it would easily be spotted by predators if it was placed in a rocky stream bed. By placing young salmon into areas matching their camouflage, conservationists can help increase their chances of survival.
Young salmon showing variation in parr marks (photo by S. Pedersen)
“You want to match the stream characteristics to fish that used to be there,” says Boulding. “This is important when you have a number of streams to choose from.”
The team also identified QTL for other characteristics such as length, weight and colour. According to Boulding, these are all traits that can be tailored to help match “introduced” salmon to those that were once native to a particular environment.
Atlantic salmon restoration efforts are already taking place across Eastern Canada. For example, Bring Back the Salmon is a restoration effort focussed on re-introducing Atlantic salmon to Lake Ontario and the surrounding area. With the important genetic information provided by Dr. Boulding and her research group, ecologists can select the best varieties of salmon to use in this and other projects.
Funding was provided by the Natural Sciences and Engineering Research Council of Canada. Salmon were reared by the Department of Fisheries and Oceans's Biological Station in St. Andrew's New Brunswick.
Read the full article in the journal Genome.