逐次加入のある資源におけるパラメーターの推定について-I : 太平洋赤道海域のキハダにおける推定値への逐次加入の影響

概要

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1) In tuna longline fishery, yellowfin tuna seems not to be recruited fully at a certain age, but sequentially over some years. 2) The bias of estimated value of parameters by two ordinary methods, especially of the natural mortality coefficient (M), in age at which the recruitment is not completed is evaluated by simulation. 3) When the rate of recruitment is derived from the normal distribution assuming that the fish recruits from Age 1 to Age 5 and the mode of recruitment is at Age 3, ?? in Ages 1 and 2 was impossible to obtain, and ?? in Ages 3 and 4 are smaller than M in each case. The bias of ?? in ages older than 4 is negligible. 4) When the rate of recruitment calculated from the catch data and given values of M and q are used, ?? in Ages 3 and 4 are different from the given value, and that bias of ?? varies in each subarea. Especially in the subarea where the rate of recruitment changed, the variation is remarkable. 5) In a fish population which has sequential recruitment, it is necessary to formulate a new method of estimating population parameters.
公益社団法人日本水産学会の論文