Méthode d'estimation de la surface de pêche d'un casier à l'aide d'une filière expérimentale

The experimental design of the capture field area of baited whelk-pots involves, as a controlled factor, four different spacings between pots (6, 12, 24 and 36m), randomly distributed along a ground line. This spectrum of values is sufficiently broad to preclude overlap of capturing fields of sorne pots. Taking account of the patterns of the M2 tidal currents in the area studied, an ellipse was chosen as a geometrical model of the shape of the capture field. Semimajor and semiminor axes were estimated by least squares, the expected catch per pot being defined as a decreasing function of the area of overlap with adjacent capture fields. · Experimental fishing of Buccinum undatum L. was carried out in the Channel Isles region (Western Channel), and provided estimates of the area fished by a whelk-pot (373m2 ; S.E. 98m2), and of the local density of the whelks (ca. 0.4 individuals rn - 2; S.E. 0.1 ind. rn- 2). The proposed design is easy to generalize, provided that sorne information concerning the advective and diffusive processes is available.