Reproductive bionomics of Spotted Scat, Scatophagus argus (Linnaeus, 1766) off South-east coast of India

The study emphasizes reproductive biomomics, population structure and length-weight relationship of spotted scat, Scatophagus argus , off Indian waters. Sampling from Ennore, Muttukadu, and Mandapam along the South-east coast of India registered their occurrence during the south-west monsoon (June to August) and north-east monsoon (October to December) with peaks during July and November. There exists a biased sex ratio towards females in the spotted scat population. Reproductivity performance was assessed based on the gonad-somatic index, which aptly correlated with peak spawning season. This led to a description of six stages of ovarian and testicular development. Histological studies further revealed five stages of oocyte and four stages of sperm maturation. Morphometric analysis indicated that the total length (TL) of the fish in the samples ranged from 9.2 cm to 18.3 cm in females and 12.0 cm to 17.6 cm in males. Length-weight equations of w = 0.0337 L ^2.998 and w = 0.055 L ^2.804 were derived for females and males, respectively. The relationship showed that the exponent “b” value was below 3, with a negative allometric equation documenting compressed body shape. This study provides baseline data on the population structure, length-weight relationship, sexual maturity, and spawning periodicity of Scatophagus argus in Indian waters.