Reproduction, stocks and fishery of pollock in the eastern Bering sea

Abstract

The age and size of the maturity reproduction of pollock individuals are subject to significant interannual variability. The main spawning of pollock on the shelf was observed: in Unimaksky district – in the 2nd decade of March and the 2nd decade of April, above depths of 75–100 m; in Pribilovsky district – in the 3rd decade of April, above depths of 70–75 m; in Matveevsky district – in the 1st decade of May, above depths of 115–140 m. In Unimak district, the main concentrations of pollock during the peak of spawning spatially coincided with the main concentrations of egg. Such coincidences were observed irregularly in the Pribylovsky and Matveevsky districts. In March, the larvae that originated from winter spawning lived not only above significant depths – 600–2000 m, with a favorable temperature regime (3,1–4,5 C), but also in the shelf zone of the Unimaksky district, where the development conditions are more severe. The largest catches of larvae of the spring generation were observed in mid-May and early June. The larvae of the spring generation are confined to the spawning ground, which indicates the absence of drift. The main reason for the variability of stocks is the number of generations included in the fishable stock. From 1980 to 2024, there were 8 high abundance generations. The average annual pollock catch in the area over a 45-year period was 1,2 million tons. Pollock stocks in the eastern Bering Sea are highly stable. Periods of low stock levels are short-lived and last several years. The average long-term exploitation rate was 12,6%, which indicates a relatively low harvest level.