Anadyr сhum salmon Oncorhynchus keta: new sights to reproduction, dynamics of stock and regime of exploitation

A hypothesis is proposed regarding the critical cyclic impact of low air temperature at the spawning grounds in winter on survival of the Anadyr chum salmon offspring. Periods of this species high and low abundance alternate approximately every 20 years because of specific environmental influence on the spawning grounds of different quality in conditions of permafrost. The limited number of 450–500x10³ ind. are able to spawn in relatively cold conditions when the spawners use only the high quality spawning grounds, whereas they spawn much wider in the number of 1150–1200x10³ ind. in warmer conditions. The water supply for low quality spawning grounds due to subsurface underflow is supposedly available in warm winters but dries up in cold ones. Indeed, the current level of the Anadyr chum salmon stock is too low for commercial using, so strategy of the stock exploitation should be revised for its recovery. There is proposed to regulate escapement of chum salmon spawners to the spawning grounds in dependence on their total number within the river basin, to ensure the optimal spawning density but never less than 500x10³ spawners. To reduce the fishery pressure on the natural stock, an artificial stock of non-native chum salmon could be established in the basin of Anadyr Liman. pressure on the natural stock, an artificial stock of non-native chum salmon could be established in the basin of Anadyr Liman.

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