Fisheries Biology of the twobar Seabream, Acanthopagrus bifasciatus from the Egyptian Sector of the Red Sea

Abstract

The growth and reproductive biology of the commercially important reef fish, the twobar seabream, Acanthopagrus bifasciatus, were investigated in order to evaluate the impact of fishing on its resource, and to derive information required for its management in the Red Sea. Samples were collected during 2017-2019 from Hurgada fishing harbor. Age was determined by using sagittal otolith. The maximum age recorded was 18 years. The von Bertalanffy growth parameters fit to length at age data were estimated as K = 0.131 year−1, L ∞ = 59.48 cm (TL), t o = −1.778 years. The length-weight relationship for combined sexes was represented by the equation, W=0.0135*L 3.1112 which exhibit positive allometric growth. Spawning was recorded during January and February, and the mean sizes and ages at first sexual maturity were 27.2 cm (2.9 years) for males and 30.1 cm (3.6 years) for females. Sex ratio was (females 50.5%, males 48.4% and hermaphrodites 1.1%). Sex ratio by size indicated that females were dominant among small/young fishes while males were dominant among old/large fishes. This suggested a protogynous hermaphrodite life history style, which may be widespread in Acanthopagrus species. The rate of fishing mortality (F cur = 0.238) exceeded the target (F opt = 0.121), and the limit reference points (F limit = 0.161). Further expansion of the fishery should be constrained.