On the population characteristics of anadromous Tenualosa ilisha (Hamilton, 1822) occurring from River Brahmaputra, India

Abstract

Tenualosa ilisha, commonly called Hilsa, is a highly prized species, which has declined in River Brahmaputra, India. The study was carried out for one year and a total of 1,026 individuals were sampled at monthly intervals. In the study, the following growth parameters were observed: asymptotic length (L∞) = 445 mm, growth coefficient (K) = 0.5 year^-1, and age at length zero (t₀) = −0.5 year^-1. Growth performance index (φ) was estimated to be 2.996. Natural mortality rate, total mortality, and fishing mortality was found to be 0.51 year^-1, 1.57 year^-1, and 1.06 year^-1,respectively. Exploitation ratio (E) was found to be 0.675, which indicates that the species is slightly over-exploited. It was seen that length groups that represented the catch in the Indian part of River Brahmaputra comprised fishes of 0–4+ years age. The present study was carried out to assess the population characteristics of this commercially important species from the Indian part of Brahmaputra River, which will contribute towards sustainable fisheries management.