ESTIMATION OF THE FUNCTIONAL FORM OF SELECTIVITY BY BAITED HOOKS - A GRAPHICAL APPROACH

A recently proposed graphical technique for exploring the selectivity of hooked fishing gears, involving the plotting of catch ratios against fish length, is further developed and illustrated. This technique can provide first estimates of the functional form of selectivity curves and sometimes estimates of some parameter values as well. It is therefore a useful preliminary to nonlinear estimation of hook selectivities.