Density-dependent size selectivity in Antillean fish traps

摘要

Size selection in fish traps is often considered to depend only on mesh size and fish length. A fishery-independent trap survey conducted in three islands of the Lesser Antilles showed important differences in location of the left arm of the length-frequency distribution (selection profile, and average selection lengths L-50) among sampled sectors, in spite of standardized gear and processing methodology. Differences in size structure of the populations could cause such gaps only in sets of conditions which are highly unlikely, if not impossible, in real situations. Differences in the selection process (probability for a fish to be retained by the mesh) are, therefore, thought to be the factors explaining these observations. The inverse relation between the average catch/trap and the shift of the selection profile strongly suggests that fish escapement through the mesh by squeezing is a density-dependent process, which confirms previous observations by other researchers.