Biology and exploitation of pikeperch, Stizostedion lucioperca (L.), in the Baltic Sea area

Abstract

In the Baltic Sea, there are considerable environmental gradients from north to south and from littoral areas to the open sea. These gradients include both abiotic (e.g. salinity and temperature) and biotic parameters (e.g. prey and predator abundances). The Baltic Sea thus forms a variable, and with respect to salinity, extreme, environment for a typical limnetic and warm water species like pikeperch. It is forced to spawn in shallow inlets, estuaries and bays where salinity is lower and temperature higher than in exposed areas. Pikeperch occur mainly in eutrophicated archipelagoes and bays where the spring and summer temperatures are high. It has expanded its distribution in recent decades, in response to increased coastal eutrophication. Pikeperch is also favoured by high summer temperatures, as shown by a positive correlation between temperature and year-class strength. Pikeperch populations are heavily affected by human disturbances and exploitation. In many areas it is economically the most important species. The effects of intensive fishery on pikeperch populations are largely unknown, as is the ecological significance of pikeperch as a piscivorous predator.