Per Recruit Models for Stock Assessment and Management of Carp Fishes in the Pattipul Stream, Sheetalpur, Saran (Bihar)

Abstract

The Per recruit models were applied to assess Major carp stock in the Pattipul of Bihar showed rapid increment in Yield per recruit (Y/R) at low values of fishing mortality (M=0.17/year) and age at first capture (Tc=0.5 years and increasing F (0.50/year) as 1068 g per year. The Y/R above this level was constant or slightly decreased and the recent F value is higher than the biological reference points as F0.1 (0.15 per year), FSB40% (0.13 per year), FSB50% (0.08 per year) and FSB25% (0.24 per year). The Tc increase by one year resulted in slight increase in Y/R, while additional Tc increase led to decrease in Y/R values. The Tc increase in F required to obtaining the maximum Y/R until reaching a optimum state as initial recruitment at constant M, while recent F value gives small increase in recent level of F, increasing the Tc by one year would result in a small increase in biomass per recruit (B/R). The Tc increase caused a gradual increase in B/R, followed by a decline after a certain value of Tc. These results provide evidence of recruitment over-fishing at all optimum fishing levels, and so sustainable management and conservation of Major carps in Pattipul would require a decrease in F to levels less than F0.1 and FSB40%, which can be achieved through a reduction in fishing effort but not through an increase in Tc.