D.3 Selectivity
The selectivity coefficient qFC,FX may be given by one of five functions depending on the gear used by the fishery. It may be a constant proportion applied to all age classes or it may be size based and calculated based on a normal, logistic, lognormal or gamma distribution. The selectivity of the gear with regard to cohort i of vertebrate group FX (q,i,FX) is given by one of the following equations (depending on the selectivity curve of the gear). If the selectivity curve is a constant
(D.8)
if a logistic selectivity curve is used for the gear then
(D.9)
if a normal selectivity curve is used for the gear then
(D.10)
if a lognormal selectivity curve is used for the gear then
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