Population dynamics of Indian river shad Gudusia chapra (Hamilton, 1822) using length frequency analysis for fisheries management in a floodplain wetland of Ganga River Basin, India

Abstract

The small-scale fisheries sector plays very significant role in Indian fisheries. Fish life history parameters such as growth and morality are considered important factors for their conservation and management. Accordingly, the population parameters of a commercially important freshwater clupeid fish, Gudusia chapra (Hamilton, 1822) of Mathura beel, a tropical oxbow lake in West Bengal were investigated on the basis of primary data using a FiSAT-II software package. A total of 2062 specimens of both sexes combined, exhibiting a length (TL) range 1.7–15.4 cm and a weight range of 1.14–35.69 g, were collected from different sites of the wetland during October 2017–September 2019. The growth parameters L_∞, K and t₀ of the species were 16.55 cm, 1.10/year and −0.02, respectively. The growth performance (ϕ) was 2.48. The estimated mortality rates Z, M and F were 2.72, 1.25 and 1.47/year, respectively. The current exploitation ratio (E) was estimated to be 0.54 based on the length-converted catch curve. Analysis of the relative yield per recruit and relative biomass per recruit model indicated that the current E value is approaching an E_max value of 0.56. The maximum sustainable yield of this species was estimated to be 10.7 t, compared to the present annual yield of 11.5 t. For optimal fisheries management and a reduced risk of over exploitation, the current exploitation rate should be reduced by about 40% to achieve E_0.5 as a target reference point. The information generated in the present study will facilitate optimal management of the resources for sustainable fisheries management and conservation of G. chapra.