Benefits from fish stocking—experiences from stocking young-of-the-year pikeperch, Stizostedion lucioperca L. to a bay in the Baltic Sea

Abstract

To evaluate the economic viability of fish stocking, it must be possible to identify the stocked fish in the wild. To find a suitable marking method, young-of-the-year (YOY, length 8–10 cm) pikeperch ( Stizostedion lucioperca) were tagged in different ways and stocked in ponds. Over a 185-day winter period, there was no significant size-dependent mortality, but clear differences in mortality among fish marked in different ways. Fingerling and streamer-tagged fish had significantly lower survivorship than fin-clipped (left pelvic fin) and colour-marked (Alcian Blue) fish, which were not different from controls. Seventeen thousand, seven hundred sixty-six YOY pikeperch were fin-clipped and released in a large bay of the Baltic Sea on the Swedish east coast in October 1991. The following year, 23% of all 1-yr-old fish caught came from this stocking. The proportion of marked fish was considerably higher close to the release site, showing that they were relatively stationary during their first year of life. A simple economic analysis demonstrates that pikeperch stocking can be very profitable. Based on the capital invested in the stocked YOY, the economic yield corresponds to an annual interest rate of 43%.