Resorption of developing oocytes as a regulatory mechanism of formation of individual and population fecundity in walleyepollock Theragra chalcogramma (Gadidae)

摘要

The resorption of developing oocytes was studied in females of walleye pollock Theragra chalcogramma from different regions of the Bering Sea, the Sea of Okhotsk, and the Sea of Japan. The characteristics of partial and total oocyte resorption changed depending on the year, season of the year, and age or size of the fish. The largest number of individuals with resorbed oocyies was registered at the middle and at the end of the spawning season. The number of atretic developing oocytes in maturing females increased at a time of larger abundance of the spawning stock and during the wannest years with higher water temperatures. Influence of the oocyte degeneration on the formation of individual and population fecundity was assessed in the walleye pollock from the Navarinskii district of the Bering Sea. The decrease of the population fecundity caused by atresia of oocytes of the current year generation reached 20.5 percent in 1988 and 17.7 percent in 2000.