Some Issues Related to Reproduction of Pacific Cod Gadus macrocephalus in Waters of the Eastern Coast of the Northern Kuril Islands and the Southern Extremity of Kamchatka

摘要

The analysis of data collected in December 1996 and 1998 on the reproduction of cod Gadus macrocephalus in Pacific waters of the northern Kuril Islands and the southern part of Kamchatka was performed. It was shown that the individual absolute fecundity of the cod varies within 0.197-9.729 million eggs and the relative fecundity, in the range of 24-1386 eggs. The fecundity of 1000 mature females comprises 2179-2449 million eggs. The low individual fecundity of fish is related to pseudobranchial tumorgrowth. The main role in cod reproduction is played by females of two-three size groups characterized by the highest numbers of mature females. It is suggested that different fecundity within the range of Pacific cod is related to environmental conditions, in particular, water temperature in the spawning grounds during spawning rather than to the habitation latitude.