Genetic determination of the contribution of stocked and wild atlantic salmon, salmo-salar l, to the angling fisheries in 2 spanish rivers

From 1983 to 1986 the Rivers Ason and Nansa (northern Spain) were stocked with over 100 000 eyed ova year−1 from a Scottish hatchery in an effort to increase angling catches of Atlantic salmon. An inherent genetic marker was used to estimate the contributions of stocked and wild fish from these year-classes to the 1988 rod-and-line fishery. Stocking with foreign ova yielded 0.9 fish per 10 000 ova in the R. Asón and zero fish in the R. Nansa. Natural egg deposition yielded 4.1 and 4.9 fish per 10000 ova, respectively. Reasons for the difference in performance between stocked and wild fish are examined.