適正な漁獲量をきめる試み

概要

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Under a certain environment, as the number of immigrant fishes aged a years may be assumed to have a certain upper limit, n, and as the survival. rate, ρ, and the fishing rate, f, may be assumed not to vary, then the next relation may be considered nearly to hold between the number of immigrants, n, and the number of parents, ρp-an/1-ρ; dn=bnn/nd (ρp-an/1-ρ), in case the p-aged female begins the first spawning and any parent bears b immigrants in every year when the population is very poor. By solving this equation, we know that n/n _??_ 1 when b ρp-a/1-ρ_??_3 Putting ρ=ρ_??_ when f=o, and putting b ρp-a/1-ρ=3, then the maximum value of the fishing rate, f, allowable ro conserve the fish population may be expressed by f=1-ρ/ρ0. And assuming that the amount of the population is x times its original value, then x=1-ρ0/1-ρ.
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