The abundance and patterns of the egg and larval spatial distribution of Eastern Baltic cod Gadus morhua callarias (Gadidae) in 1931–1996

Abstract

According to ichthyoplankton surveys of AtlantNIRO and published sources, the data on abundance of eggs and larvae of eastern Baltic cod Gadus morhua callarias at different spawning grounds of the Baltic Sea in 1931–1938, 1949–1956, and 1991–1996 are considered. We show that a similar type of spatial distribution of eggs and larvae of cod with localization of the greatest amount of its early ontogenetic stages in the Bornholm Basin in the southwest of the sea was observed in the 1930s and 1990s. The extension of the area of distribution was accompanied by an increase in the numbers of eggs and larvae of cod in all areas of the sea, and its decline was followed by a decrease in numbers, in the first turn, at northeastern spawning grounds in the Gotland Basin. The period of high numbers of eggs in 1949–1956 coincided with the century maximum of salinity of the near-bottom water layer.