Stock assessment of Japanese threadfin bream, Nemipterus japonicus (Bloch, 1791) from Veraval water

Abstract

Fishery, population characteristics and stock estimates of Nemipterus japonicus was studied during 2006-2010 from Veraval water. Average annual landing was 5,577 t, which contributed to 4.49 % to the total trawl landings. Length-weight relationship showed growth was allometric for the species. L∞, K and t0 were estimated as 345.6 mm, 0.60/year and -0.1132 year. Total mortality rate (Z), fishing mortality rate and natural mortality rate (M) were estimated as 4.02/yr, 2.82/yr and 1.2/yr respectively. Exploitation ratio (E) was found to be 0.70 which showed overexploitation of the species. Length at capture and length at maturity were estimated as 165.47 mm and 180 mm respectively. Recruitment of the species was continuous with a peak in June. Thompson and Bell prediction analysis showed at present fishing level, there is depletion in the initial biomass, spawning stock biomass giving less revenue. Hence it is advisable to reduce the effort by 20%.