Rearing and release experiments with Baltic cod

摘要

Baltic cod was reared at an experimental rearing station at the Swedish west coast with the purpose of (i) development of intensive rearing techniques applicable for Baltic cod and for (ii) the release of young cod in enhancement experiments. The Baltic stocks have been suggested to show adaptations to the brackish environment (salinity 5-20 ppt) (Segerstrale 1965; Bagge Thurow, Steffen-sen & Bay 1994) Reproduction is possible at salinity down to ca 11 ppt (Westin & Nissling 1991). Baltic cod (Gadus morhua) has shown strong abundance variations during the previous century. The Baltic cod population is assessed as two separate stocks: the eastern Baltic stock and the smaller western stock (Brander 1994). A strong decline in the population size from the mid-1980s until today is partly caused by poor management resulting in overfishing.This has reduced the recruitment of cod to the northern part (Gulf of Bothnia) of the Baltic Sea to almost zero, with severe effects on the local fishery.