Stock status of Greenback mullet, Planiliza subviridis (Valenciennes, 1836) from the Shibsa River, coastal water of Southern Bangladesh through length-based models

Our study describes the stock status of Planiliza subviridis (Valenciennies, 1836) by emphasizing on growth pattern, growth parameters (asymptotic length, L∞; asymptotic weight, W∞; growth co-efficient, K; age at zero length, t0), sexual maturity size (Lm), age at sexual maturity (tm), growth performance index (Ø'), life-span (tmax), relative weight (WR), form factor (a3.0), mortality rates ( Z, M and F), exploitation rate (E), maximum sustainable yield (MSY), and relative biomass of P. subviridis from the coastal Shibsa River, Southern Bangladesh. A sum of 317 individuals of P. subviridis ranging from 6.50-19.70 cm total length (TL) was sampled during July 2017 to December 2019. The overall b value indicated isometric growth (b = 3.0) pattern. The estimated L∞, W∞, K, and t0 were 20.79 cm, 93.20 g, 1.02 per year, and 0.015 year, respectively. The Lm was estimated as 11.65 cm in TL and tm was 0.82 year. The tmax was 2.93 year and Ø' was 2.64. Fulton’s condition factor was found most suitable for this species. Further, the average relative weight (WR) indicated that the habitat was in a stable situation. In addition, the Z, M, and F were obtained as 2.23, 1.57, and 0.66 year-1, respectively. Length at maximum yield per recruit (Lopt) was estimated as 13.74 cm. Further, the E (0.30) and MSY, maximum sustainable Yield (0.29) indicated balance harvesting occurred in the coastal Shibsa River. Additionally, the relative numbers of survival, individual growth in weight, and cohort biomass was 24%, 40.0 g, and 100% (9.0 kg) when P. subviridis reached 1.2 years. Consequently, the results of our study will be supportive to implement a proper management strategy in the coastal Shibsa River and adjoining ecosystems of Bangladesh.