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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. [ABSTRACT FROM AUTHOR]

Population characteristics and exploitation level of Anabas testudineus from Rudrasagar lake, North-eastern India were studied to understand the dynamics of resource for suggesting necessary strategies for sustainable exploitation. A total of 1187 specimens were sampled to collect the length frequency data from May, 2015 to April, 2016. The length-weight relationship of the fish was found to be Log W = - 4.08+2.9 LogL (r²=0.99). The Von Bertalanffy growth parameters i.e., asymptotic length (L∞)and growth coefficient (K) were estimated using ELEFAN-I as 216.25 mm and 0.78 yr- 1respectively.The growth performance index (φ') was calculated as 4.56. The approximate longevity (Tmax) was estimated as 3.8 years. The total mortality (Z), natural mortality (M) and fishing mortality (F) rates were estimated to be 1.95, 1.54 and 0.41 per year, respectively. The exploitation ratio (E) and exploitation rate (U) were observed to be 0.21 and 0.18, respectively. The results of relative yield-per-recruit (Y'/R) and relative biomass-per-recruit (B'/R) estimated as a function of Lc/L∞ and M/K were 0.46 and 1.95 respectively. The MSY level was estimated at 3.8 tonnes per year at F factor-0.8. Since the current level of exploitation of the species is well below Emax(0.50) and the observed landings are lower than the MSY level, it could be concluded that the fish is presently underexploited in the Lake. Reasonable fishing effort can be increased in order to obtain more yields so as to reach the MSY level and in that way increase the income of the economically poor fishermen communities of North-eastern India. [ABSTRACT FROM AUTHOR]