Method to determine the mesh size of a purse seine and its application to Peruvian jack mackerel.

概要

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Equations to determine the mesh size of purse seine were derived by applying the cumulative normal distribution as a selection ogive. Gilling of a fish in a mesh was the only consideration. Afterwards, verification of the equations derived and determination of the mesh sizes for a Peruvian jack mackerel were undertaken. The results obtained were as follows;1)The appropriate mesh size could be expressed as Mo=(K Co/2)(-3σo/Co+L) and the inappropriate mesh size as M'=a+b L, where L is the fork length, K the rate of body contraction, Co the girth/fork length ratio of operculum girth (Go), σo a standard deviation of Go, a and b are constants. 2) Equation obtained from Mo was verified, by applying the inappropriate mesh size of purse seine (M'), that it was correctly derived. 3) Mo and M' could be empirically expressed as Mo=-6.92+0.193 Li and M'=0.240+0.199Le, where Li is the minimum fork length and Le the mean fork length. The appropriate and inappropriate mesh sizes for Peruvian jack mackerel were calculated to be 43.8mm and 62.5mm, respectively for all seasons.