Biology and fishery of barred spiny eel, Macrognathus pancalus Hamilton

Abstract

Background. The barred spiny eel, Macrognathus pancalus Hamilton 1822 (known also as the striped spiny eel) has high food- as well as ornamental value in India and its neighbouring countries. The natural resources of this species are declining due to over exploitation and habitat changes. The aim of this study was to provide necessary inputs on food habits, reproductive biology, and fishery of the species for artificial propagation programs and fisheries guidelines for conservation of its natural populations. Materials and methods. Fish samples were collected monthly, for a period of 12 months, from an oxbow lake, situated in the Ganga River basin, India, during June 2004-May 2005. Food habits, reproductive biology, length-weight relation, fishery resource status, asymptotic length (L∞), length at maturity (Lm) and length at maximum possible yield (Lopt) for the species were studied. Results. The fish subsisted mainly on insect larvae. Fecundity range was 227 (fish: 10.7 cm and 5.03 g) to 8310 (fish: 17 cm and 30.31 g). Length at first maturity calculated through maturity curve was 10-11 cm (males) and 11-12 cm (females) in total length. The breeding period was within March-September. The regression model fitted for length and weight of the fish was Log W = 3.3224 Log L - 6.0793, R2 = 0.9094 for male; Log W = 3.3378 Log L - 6.0716, R2 = 0.9183 for female. The exponent ‘b’ for male and female varied significantly from ‘3’ indicating allometric growth pattern. The relation of fecundity with total length and weight of the fish was Log F = 2.9574 Log L - 3.2055, R2 = 0.3728 and Log F = 0.9684 Log W + 2.0934, R2 = 0.4716. Immature specimens dominated in the catch. The estimates obtained for L∞ = 18.8 cm (s.e. range 15.9-22.3 cm), Lm male = 10.8 cm (s.e. range 7.7-15.1 cm), Lm female = 12.3 cm (s.e. range 9.3-16.3 cm) and Lopt = 11.3 cm (s.e. range 9.6-13.4 cm). Biomass of the species in experimental fishing was high during October-January, which was also the period when immature specimens were lowest. Conclusion. Closed or less intense fishing for the species during March-September and capture of only specimens above 14 cm length would help conservation of the natural stock of the fish in the wetland.

Keywords

• biology
• fishery
• Macrognathus pancalus
• barred sp