Determining stock size and genetic composition are fundamental components for managing healthy fish populations.
To stray or stay: population genetics of sea trout helps guide management
New research led by the University of Exeter in partnership with the Environment Agency and Westcountry Rivers Trust highlights how studying population genetics could improve the management of sea trout within the southwest.
The biology of anadromous fish species is quite fascinating. Although born in fresh water, anadromous species migrate to and spend a large proportion of their lives at sea, but return to fresh water to spawn and reproduce. Sea trout, Salmo trutta, are a recreationally important anadromous fish species and are the focus of ongoing monitoring and management efforts by the UK Environment Agency.
Determining stock size and genetic composition are fundamental components for managing healthy fish populations. To investigate the prevalence of straying and further understand the mixed-stock status of sea trout fisheries, researchers utilised a panel of DNA microsatellite markers – an established method for genetic stock analysis – to look at trout populations in southwest England. The team compared genotypes from more than 3,000 trout from 82 populations spawning across 29 rivers in the southwest, including the Lynher, Tamar and Tavy, all important recreational sea trout fishing rivers. Their results showed that sea trout frequently stray from natal rivers (i.e. rivers of birth) within the southwest and have marked genetic population structure.
Dr. Andrew King, lead author and geneticist with the Molecular Ecology and Evolution Group stated, "Our results provide insight into the behaviour of sea trout, and suggest that straying of returning adults between rivers may be more frequent than was previously thought. The results raise interesting questions as to how such mixed-stock rod fisheries for sea trout should be managed. Indeed, in light of our findings, one local stakeholder group, the Tamar Fisheries Forum, has changed catchment management boundaries to include all the rivers sharing the Tamar estuary."
The results published in Fisheries Management and Ecology will help to guide management of recreational fishing in the studied areas.
Date: 24 February 2017