Some Aspects on Distribution and Biology of the Spinycheek Grouper Epinephelus diacanthus (Valenciennes, 1828) from the Arabian Sea off Oman

Abstract

Spinycheek grouper (Epinephelus diacanthus) distribution and biology were studied based on the samples collected during a demersal fish survey conducted by R/V "Al Mustaqila 1" along the Arabian Sea coast of Oman between September 2007 and September 2008. This species was relatively evenly distributed along the coast and occurred in depths from 22 to 182 m with total length range of 6.7–58.1 cm (mean 36.8 ± 0.4 cm SE, n = 715), and weight range of 4.0–2575 g (mean 834.4 ± 22.9 g SE). The sizes most commonly encountered groupers ranged between 33 and 39 cm TL. Differences in size between males (mean 38.5 ± 0.6 cm SE, n = 224) and females (mean 36.7 ± 0.4 cm SE, n = 475) were registered. The length–weight relationship for both sexes combined was TW = 0.0097 TL^3.0896 (R² = 0.99). Females were outnumbered males during the survey period where the overall male to female ratio was 1 : 2.13. Ripening and mature males and females were occurred from February to October, and the peak of spawning was found in May–June.

Keywords: Oman, Arabian Sea, Epinephelus diacanthus, distribution, size structure, sex ratio, spawning