Journal of Aquaculture Research & Development

Abstract

On the Biology of Siganus rivulatus Inhabits Bitter Lakes in Egypt

El- Drawany

The present work was carried out to study the age, growth, length-weight relationships, spawning season, length at first sexual maturity and mortality of the commercial Rabbit fish, Siganus rivulatus, inhabits Bitter Lakes in Egypt. Fish samples which were collected during the period from January to December 2011 were selected to represent all fish size categories in the catch. Each fish specimen was measured, weighted and then dissected to detect the maturity stage of the gonads. The annual rates of total, natural and fishing mortality were calculated as 0.8840, 0.2214 and 0.6626yr–1 respectively. Current exploitation rate 'E' was estimated at 0.75. The length-weight relationships for males and females were estimated, respectively as:

W=0.01042×L3.0101 and W=0.00952×L3.042.

The age data derived from the otolith readings were used to estimate the growth parameters of the von Bertalanffy growth equation. The estimated parameters were: L∞=35.5 cm, K=0.0849 and to=-0.843 for females, otherwise they were: L∞=36.5 cm, K=0.0786 and to =-1.00382 for males. It was found that, both males and females matured at a total length of about 15.4 cm. The natural spawning period of this fish species is in the summer, from May to July.