Reproductive biology of the sleeper goby, Butis gymnopomus (Bleeker, 1853) from the Merbok Estuary, Kedah, Malaysia

Abstract

Biological aspects of the sleeper goby, Butis gymnopomus were studied based on samples collected from the Merbok Estuary between May 2010 and April 2011 using barrier nets. The catch rate fluctuated between 162.5 g per boat trip (g bt-1) in August and 5,000.0 g bt-1 in November. The total length ranged between 14.5 and 33.5 cm and body weight ranged from 25.8 to 276.8 g. The exponent values (b = slope) of the length-weight relationship in males and females were 2.9627 and 3.0542, respectively, indicating an isometric growth pattern for both sexes. Two pronounced peaks of gonadosomatic index observed in females were in January and in August. Synchronous reproductive behavior was observed in both males and females coinciding with the secondary and primary rainy seasons. At first maturity, males were slightly longer (22.8 cm) than females (21.3 cm).