抄録
The reproduction situation of chum salmon in Alaska has not been studied because of its lowest economical value and small size of stock. However, it has a important meaning to estimate the effect of artificial propagation for chum salmon in Japan and also it is neces-sary to know the situation of fishery management for chum salmon in Alaska.
In this paper, the reproduction situations of chum salmons both in Central and Southeast-ern Alaska are studied using Ricker's formula (R=aEa-bE), in which the numbers on es-capements (E) and returns (R) are estimated by the catch statistics from 1920 to 1961 under the adequate assumption of fishing rate, which is 0.5 for Central Alaska and 0.5-0.65 for Southeastern Alaska.
Following tables and figures resulted from above estimations show that 1) the number of returns per spawner in MSY is about 3.2-3.6 fishes, and 2) the reproduction situation in South-eastern Alaska has fallen since 1950, while 3) the recent exploitation in Central Alaska does not realize full utilization.
