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Discrepancy between otolith and tag-recovery estimates of growth for two South African surf-zone teleost species
Abstract
Growth rates determined from recovered tagged galjoen Dichistius capensis and white steenbras Lithognathus lithognathus were compared to predictions from growth models based on otolith ring counts. Galjoen could not
be sexed externally, but it was assumed that all fish >450 mm total length were females, which grow faster than males. Those smaller than this were assumed to include mostly males and were treated as a “male” sample. Male
and female white steenbras grow equivalently. Tagged “male” (n = 322), and female galjoen (n = 34) and white steenbras (n = 14) grew more slowly than the model predictions. The discrepancy is likely attributable to the physiological effect of external tags on growth.
be sexed externally, but it was assumed that all fish >450 mm total length were females, which grow faster than males. Those smaller than this were assumed to include mostly males and were treated as a “male” sample. Male
and female white steenbras grow equivalently. Tagged “male” (n = 322), and female galjoen (n = 34) and white steenbras (n = 14) grew more slowly than the model predictions. The discrepancy is likely attributable to the physiological effect of external tags on growth.
