English abstract
The Minstrel sweetlips Plectorhinchus schotaf (Haemulidae) is an important species harvested in the traditional fishery in Oman, but, there is a lack of data on their basic biology. The objective of this thesis was to provide basic biological information of P. schotaf in relation to morphometric linear relationships, length-weight relationships, condition factor, sex ratio, spawning season and size at 50% maturity. 976 samples were collected, (558 female and 418 male) from Dhofar Governorate off the coast of the Arabian Sea from March 2010 to February 2012
Females and males had different mean total length 28.04 + 3.69 cm for females and 28.63 + 4.46 cm for male and different mean total weight 353.25 = 133.68 g for females and 382.20 $ 169.74 g for males (P <0.05). All morphometric linear relationships were highly correlated (P <0.001). All length-weight relationships showed negative allometry and a significant difference between the sexes (P < 0.05). Males were better than females in condition factor which decreases with an increase in length. The gonadosomatic index showed a single protracted spawning season which occurred from October to January. There was an inverse relationship between condition factor and gonadosomatic index during the spawning season. The overall sex ratio was skewed and was significantly different from 1:1 (P < 0.001) in favor of females. The length at 50% maturity was 18.00 cm for females and 19.50 cm for males.
The current study recommends continuing fishing with passible increases in the fishing effort for this species. However it is recommended to reduce fishing effort during the spawning season from October to January. Finally it recommends that future studies concentrate on various biological and ecological aspects of this species and to use the results of the current study as a reference points.
