Note on the selectivity of meshes used by the Santos fishing fleet

Abstract

In this paper the relationship between total length and girth (circumference) of seven species: "Corvina" (Micropogon furnieri), "Pescada-foguete" (Macrodon ancylodori), "Goete" (Cynoscion petranus), "Tortinha" (Isopisthus parvipinnis), "Cangaua" (Bairdiella ronchus), "Maria Luisa" ("Paralonchurus brasiliensis), and "Oveva" (Larimus breviceps), are expressed in the form of fitted regressions. Theoretical selection lengths assuming, at the one extreme, the mesh to be completely flexible, and at the other extreme to be rigid with axes of 2:3 are calculated. The fish is assumed to be able to adopt a circular cross section. If the fish is not circular but retains its normal form, the difference in the selection length is shown to be little different. The Brazilian commercial boats fishing from Santos are shown to use a mesh which has a very low selection point well below the size of fish which are acceptable on the fish market. The Japanese boats use a much larger mesh, which select fish of marketable size.