Reproductive aspects of the native Sharpnose hammer croaker, Johnius borneensis (Bleeker, 1850) from Agusan River Estuary, Caraga region, Philippines

Abstract

Preliminary analysis on the reproductive features of the commercially important Johnius borneensis from the Agusan river estuary was studied between the months of February-April, 2017. A total of 223 specimens, of which 117 were females (b=3.356, K=0.5560) and 106 males (b=2.9054, K=0.5560) were examined. A strong coefficient of correlation was observed between the length and weight of fish samples. Overall sex ratio is 3:1 (female dominance) with a mean fecundity of 52487.5. Length at first maturity was 137mm. March to April was considered as one of the breeding seasons for J. borneensis. Mature to spawning individuals were collected at the heart of the estuary while immature individuals were observed offshores. Because of the peak fecundity and number of mature to spawning individuals in April it is initially recommended to lessen fish catch for J. borneensis within this month especially at lengths 180mm and above (spawning).