With the introduction of Purse-seiners in Karwar waters, Sardinella dayi has emerged as one of the important resources among lesser sardines. Detailed biological studies on growth, mortality and maturity made on this species indicate that fish attains a size of 145 mm, 160 mm and 180 mm in 1-year, 2-year and 3-year respectively; the total mortality rate ranging from 0.64 (1983) to 3.12 (1982), with the natural mortality (M) of 0.7961 from 1980 to 1983. Maturity studies show that this species has a protracted period of spawning extending from October- December and again from January to April on a reduced scale.