流れ藻の標識放流によるモジャコ漁獲係数の推定-II : 流れ藻の漁獲率

概要

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1) The fishing coefficient F, coefficient of drifting away D and rate of exploitation E of the drifting seaweeds are calculated for several experiments in each of which a substantial number of recoveries was obtained. 2) Most of the estimates of ακF are within the limits of 2 ?? 3% per day. Tag shedding rate M is estimated as 2% per day. If a is assumed to be one, many of the estimates of D fall within a range of 0.10 ?? 0.15, though extremely deviated values of less than 0.01 or more than 0.3 are also obtained depending upon the areas and periods of release. 3) The rate of exploitation is estimated at 7% at its minimum and 73% at its maximum. Fishing for mojako may have a substantial effect on the part of stock which enter into the fishing grounds. 4) Estimates of F obtained seem to be fairly reliable, But the effect of fishing on mojako stock would be more weak than that estimated here if mojako are also distributed outside the fishing grounds and some of them are migrating independently of seaweeds.