The Age, Growth, and Feeding Habits of the Whitefish, Coregonus Clupeaformis (Mitchell), of Lake Champlain

Abstract

This study is based on 120 whitefish collected in northern Lake Champlain (Missisquoi Bay) in 1930 and on 175 whitefish taken in southern Lake Champlain in 1931. Since the whitefish population had not been exploited commercially after 1912 in United States waters and after 1915 in Canadian waters, its study should be of interest in showing the characteristics of a population practically untouched by man. Data have been presented on length frequencies, age composition, growth, coefficient of condition, sex ratio, standard length-total length relationship, and feeding habits. The data indicated that the Missisquoi Bay population was disturbed (probably by the early fall seining of 1930) before our samples were taken so that the original length distributions no longer existed. The southern Lake Champlain material, however, showed a consistency which indicated that the population had not been exploited to any extensive degree, if at all. When the northern population was compared with the southern the former was found to differ from the latter in the following respects, which differences pointed to some disturbance of the northern stock in the lake By possession of lower modes and smaller grand averages of length. By absence of very old individuals. By absence of a series of equally abundant age groups or, in other words, by the presence of a decided dominance of one or two age groups. By a radical disagreement between the sexes in their age-frequency distribution. By a disagreement between the sexes with respect to maximum lengths attained. All of the differences between the two collections could, however, not be attributed to exploitation. The following characteristics indicated the presence of two distinct populations in the lake Presence of a spawning ground at each end of the lake. Differences in calculated lengths and increments of length (growth rates). Differences in the actual lengths and weights of corresponding age groups at capture. Differences in the coefficient of condition and the length-weight relationship. The discovery of the presence of apparently two separate populations of whitefish in Lake Champlain was wholly unexpected by us.