The biology of Barnard’s dentex, Dentex barnardi (Teleostei: Sparidae), in southern Angola

Abstract

Barnard’s dentexDentex barnardiis a relatively slow-growing, late-maturing species with an intermediate longevity (maximum recorded age = 13 years). The length and age structures of the population were similar for males and females; however, the sex ratio was female biased at 1:1.6. Growth was described by the three-parameter von Bertalanffy model as L_t = 332.14(1 e^{-0.14(t+3.97)}). The species is a rudimentary hermaphrodite and the length- and age-at-50% maturity was calculated as 220 mm fork length and 3.7 years respectively. Reproductive activity in fish sampled in southern Angola was observed over an extended period during the austral summer (August–February) and a drop in water temperature is a possible ultimate cue for spawning activity in this species. The diet consisted mainly of teleost fish and mysid shrimps. The life-history characteristics of the species render it susceptible even to low levels of fishing pressure. Owing to the paucity of information on the fisheries for D. barnardi, and the current fisheries management situation in Angola, conventional management tools are not considered appropriate. The establishment of marine protected areas is suggested as the most appropriate management strategy for the species.

Keywords: age and growth, feeding, life history, population structure, reproduction

African Journal of Marine Science 2012, 34(2): 223–231