Fishery biology of lessepsian immigrant squirrelfishes Sargocentron rubrum (Forsskål, 1775), Eastern Mediterranean Sea, Egypt

Abstract

Lessepsian Sargocentron rubrum has become common in the artisanal and semi-industrial fisheries catch. It was collected monthly from the landing site of Alexandria (Anfoushy) during 2016. Fish specimens ranged from 9.6 to 23 cm (TL) with an average of 17.30 ± 2.29 cm and from 16.86 to 214.13 g (TW) with an average of 100.28 ± 35.27 g. The exponent “b” of the L-W relationship resulted in negatively allometric mode of growth. The annual condition (K) was 1.69 ± 0.10 with maximum value 1.81 ± 0.12 (July) for combined sexes. Sex ratio (1M: 1.1F) showed the predominance of females (52.60%) over males (47.40%) during the whole year. GSI showed an elevation during spawning (June to September) with the highest value being in July, the unimodal curve referred to spawns one time per year. Length at maturity (Lm) was reported at 14 cm and 14.7 for males and females respectively. Otolith, s reading gave four years (11.6, 15.45, 18.12, and 20.43 cm) for 1st, 2nd, 3rd, and 4th, years of life respectively with the dominancy of age III (48.45%). L∞ = 27.26 cm, K = 0.276 year-, Z = 1.146 year−1. The exploitation ratio (E) was 0.395 and revealed the under exploitation status of S. rubrum with a good adaptation, the species may live and reproduce in new ecosystem. Further investigation is needed to establishing the management planning for the conservation and better exploitation of such economically valuable fishery resources. Keywords: Aging, Reproductive indices, Stock status, Sargocentron rubrum, Mediterranean Sea, Egypt