Selectivity of the gill net used in the capture of the atlantic thread-herring, Opisthonema oglinum (Lesueur, 1818)

Abstract

The present research aims to determine the selectivity of the gill nets used in capture of the
atlantic thread-herring, Opisthonema oglinum, from Caponga beach, municipality of Cascavel,
Ceará, Brazil. Data of total length (cm) were obtained from two groups, each with 780 individuals,
captured by gill nets with 5 cm and 6 cm meshes between opposing nodes, from August to October
2014. These data were described in histograms of frequency of length, being more representatives the
classes of 21.6 cm (24.23%) for the mesh of 5 cm and of 25.7 cm (23.08%) for the one of 6 cm. The
mean selection length was 23.7 cm for the 5 cm mesh and 28.5 cm for the 6 cm mesh. The selection
range was 23.7 ± 7.9 cm and 28.5 ± 7.9 cm for the 5 cm and 6 cm mesh, respectively. The equations
of the grid selection curves for the two mesh sizes were obtained, and the probability of capturing
individuals with less than the minimum length established in 15 cm was very low and corresponded
to 1.32% and 0.3% for 5 cm and 6 cm mesh, respectively.