Age, growth and feeding of the blue hottentot Pachymetopon aeneum (Pisces: Sparidae) with notes on reproductive biology

Abstract

The sparid Pachymetopon aeneum is a benthic carnivore feeding predominantly on hydroids, tunicates and octocorals. Juveniles and subadults occur on shallower reefs than the adults but the diet of all sizes is similar. The species is a protogynous hermaphrodite, sex reversal occurring between 200 and 300 mm forklength. Fifty per cent maturity in females occurs between 200 and 250 mm forklength. Peak reproductive activity was recorded between September and March. Otoliths were used to determine growth rate. Growth in length was described by the equation, L_t(mm) = 467,06(1 -e^{-0,1328(t-0,2473)}). The relationship between length and weight, W(g) = 0,00001L(mm)^3,149, was used to determine somatic growth as, W_t(g) = 2545,98(1 - e^{-0, 1328(t-0, 24731)})^3,149. P. aeneum have a potential for exploitation but the combination of late maturation and protogynous hermaphroditism could lead I to over-exploitation in a size-selective fishery.