On the late winter and early spring migration of the Indian Shad, Hilsa ilisha

Abstract

The migration of the Indian Shad, Hilsa ilisha (Hamilton), up the major river systems when they are in floods is well known. Some time ago, while making observations on the biology and fishery of Hilsa in Bengal and Orissa, a regular small-scale movement of the fish was noticed from the lower reaches of estuaries soon after the peak of winter season, even in the absence of floods (Jones, 1952). The observations were summarised by the author in the following lines (Jones, 1952, p. 66). "The two periods of migration of the fish observed during the years under study both in the Chilka Lake and the Hooghly River were correlated with floods during the monsoon rains and to the general rise in temperature of the water in the estuaries after the close of winter". In the Hooghly, this ascent of the fish takes place usually early in February and is also associated with some breeding activity (Jones and Menon, 1951). During this time Hilsa fishing operations are carried out in the river on a small-scale with the help of the Clapnet, shangla-jal. In the Chilka Lake, in Orissa, a similar migration takes place in January-February when the fish is reported to be caught in the channel area connecting the sea and the lake (Jones and Sujansingani, 1951). It is of interest to mention here that a similar activity has been recorded by Kulkarni (1951) for the Hilsa in the Narbada where there is a small run beginning in March and continuing up to the middle of April. After referring to the early run of Hilsa in the Indus and the Irrawaddy due to floods caused by the melting of snows,, he says that "in the Narbada, however, there is no such possibility, as at no stage the river passes through any snow clad mountains and there is not the slightest increase in the level of water in March and April". In the Indus the Hilsa comes up from the sea by about February and forms a fishery in the river from March to September (Day, 1873 and Quereshi, 1952). In the rivers of Burma also, it is reported to move up at the close of winter just as in Bengal (Kyaw, 1955).