Growth, mortality and stock status of five fin fish species from a tropical estuary Snigdhodeb Dutta Department of Industrial Fisheries, CUSAT, Kerala –682022

Abstract

Data from Cochin Estuary for five fin fish species were collected from January to December 2019. This study provides the first results on fishery dynamics of the species in this estuary and is aimed at estimating important population dynamic parameters and assessing the stock of this economically important fish species by the help of length frequency data collected. FiSAT II software was used for different analyses. The asymptotic length (L∞) and growth constant (K) of C.chanos were 421.05 mm and 0.71 year− 1, whereas for D.insidiator the asymptotic length (L∞) and growth constant (K) were 110.25 mm and 0.81 year− 1. The age at zero length (t0) was calculated for all examined species, ranged from − 0.07 to -0.19. The longevity (tmax) and growth performance index (ϕ) of P.planiceps were reported as 7.31 years and 4.81 whereas for M.cephalus were 2.14 and 4.6 respectively. The estimated total mortality (Z), natural mortality (M) and fishing mortality (F) of C.praesteus were 4.04, 1.37 and 2.67 year − 1, respectively, contrarily, for P.planiceps those values were 0.89, 0.49 and 0.4. The relative yield per recruit (Y/R) analysis revealed that the current exploration level is higher than the optimum exploitation rate, indicating an overexploitation of all examined fin fish species. Accordingly, needed management measures should include restrictions on fishing gear mesh sizes, reduced fishing effort and declaration of closed seasons and sanctuaries to protect these species from extinction.