Genetic stock identification of Atlantic salmon caught in the Faroese fishery

At present there is no fishery for Atlantic salmon (Salmo salar L.) in the Faroes Exclusive Economic Zone. However, where national or stock-complex management units can achieve their Conservation Limits, there is potential for there to be a managed exploitable surplus in the area. In order to inform management decisions a study was undertaken to extract DNA from historical scale samples caught in the Faroes long-line fishery and, using microsatellites, to perform genetic assignments to estimate the historical stock composition of the catch. Two genetic reference baselines were used. An Atlantic-wide cross-range baseline using six microsatellite loci was established using 1930 fish from 12 regions on the western Atlantic and the same number of fish from 34 sites on the eastern Atlantic. An eastern Atlantic baseline was developed using 14 microsatellites and the same 1930 fish from the 34 eastern Atlantic sites. Mixed stock fishery analysis was based on 656 scale samples collected during two fishing seasons, 1993/4 and 1994/5 and assigned to a both the cross-range and European reference baselines. This study provides the first direct measure of the proportion of North American salmon in catches within the Faroes EEZ, with overall 16% of the total samples being identified as of North American origin and 84% as European. Of the European fish, 62% were identified as coming from the Northern Europe (Russia, Finland, Norway and Sweden), 37% from Southern European (UK, Ireland, France and Spain) and 1% from Iceland. The study also found significant variation in stock proportions across years and through seasons. This study has provided useful estimates of historical fishery composition in the absence of contemporary samples.