POPULATION PARAMETERS AND EXPLOITATION PATTERN OF BARRED SPINY EEL, MACROGNATHUS PANCALUS

Abstract

Population parameters and exploitation pattern of the Barred spiny eel, Macrognathus pancalus Hamilton 1822 sampled from an oxbow lake in Ganga river basin, were investigated using length-weight analysis. Length-frequency based assessment using FiSAT software yielded an asymptotic length (LÂ¥) value =18.73cm TL and K (growth coefficient) = 1.2 year-1; the instantaneous total mortality coefficient (Z) = 2.39 year-1, natural mortality coefficient (M) = 1.06 year-1, fishing mortality coefficient (F) = 1.33 year-1and exploitation rate (E) = 0.56. The length at recruitment (Lr ) was 4.92 cm TL and length at first capture (Lc or L50) was 4.89 cm TL. The recruitment pattern of the fish was year-round with two pulses in a year (May-June and September-October). The population of the fish in the wetland was mortality dominated (Z/K= 2). The exploitation rate E was 0.56, while exploitation rate needed for obtaining maximum sustainable yield/recruit (Emax) was 0.52, indicating over exploitation as E (0.56) is greater than Emax (0.52). Almost 42% of the fishes in the catch were smaller than their length at first maturity (Lm = 11cm), an indication of growth over fishing, which needs to be reduced for conservation of the stock. Unregulated fishing and increase in effort from the current levels may lead to over-exploitation as the fishery is at slightly above the maximum sustainable yield.

Key words: Macrognathus pancalus, population parameters, length frequency, exploitation pattern, Ganga basin