Population dynamics of spotted scat, Scatophagus argus (Linnaeus 1766) from the Sundarbans of Bangladesh.

ABSTRACT

In Bangladesh, the mangrove areas of the Sundarbans are a hotspot for the spotted scat (Scatophagus argus), as the estuarine tributeries are significant zones for fishing, local marketing and foreign trading. Due to the widespread capture of spotted scats in the wild for a variety of uses, parameters of population were estimated using length-frequency and body weight data gathered from various sites in the southwestern forest areas of the country to comprehend the stock's status. Between May 2022 and April 2023, 1280 S. argus individuals were sampled from Khulna, Bagerhat and Satkhira. To gain insight into the population dynamics of S. argus, estimations of the growth parameters, recruitment pattern, mortalities, and level of exploitation (E) were made. For S. argus, a bit of negetive allomentric growth (b = 2.95) was observed. Moreover, the growth performance index (φ'), the asymptotic length (TL∝) and the growth coefficient (K) were 2.83, 34.65, cm and 0.56 yr-1, respectively. Natural mortality (1.08 yr-1) was lower than fishing mortality (1.12 yr-1). In the wild, this species recruits throughout the year, reaching its peak between October and January. By fishing gear, 50 % of the S. argus were caught between 7.71 cm and 9.43 cm. Moreover, high fishing mortality was assumed in both the small group (11-15 cm) and the large group (29-33 cm) of S. argus by virtual population analysis (VPA). It was discovered that the E for S. argus was 0.51, over the maximum permissible limit (Emax = 0.48). In summary, it is discovered that the S. argus population is overexploited. Therefore, in order to preserve this popular fish species and avoid local extinction, spotted scat resources should be taken into account under appropriate fisheries management guidelines. These findings will guide policymakers to manage the species accordingly.