A Comparative Analysis of the Winter Feeding Habits of Two Benthic Stream Fishes

THIS represents one portion of a study of a small headwater stream typical of those found in western New York. It deals with the feeding habits of two benthic obligate fishes, the barred fantail darter, Etheostomaf.flabellare (Rafinesque), and the northern mottled sculpin, Cottus b. bairdi Girard, both simultaneously occupying the same habitat. There have been many studies on the food habits of fishes (e.g., Forbes, 1888; Kraatz, 1928; Langford, 1938). Various aspects of the subject have been investigated, for example, the utilization of the limnetic crustacea for food by Leucichthys artedi (Langford, 1938) or the food of gars (Lepisosteus spp.) in relation to fisheries management (Lagler, Obrecht and Harry, 1943). Some investigators have attempted to ascertain the similarity in food between two species occupying the same habitat. Frequently they have been concerned with an economically desirable species versus one of little economic importance (Van Oosten and Deason, 1938; Clemens, 1950; Hunt and Carbine, 1950). Forbes and Richardson (1920: 314) reported the stomach contents of six fluviatile individuals of Etheostoma f. flabellare to be twothirds midge larvae; about one-fourth were small mayflies, and the rest were copepods. Turner (1921) found the stomach contents of 25 individuals to be primarily midge and mayfly larvae, almost to the exclusion of everything else. The occurrence of these two forms ranged from 80 to 100 percent; however, he made no attempt to distinguish between the various mayflies. Koster (1937) reviewed the feedinghabit studies of Cottus b. bairdi. His own work on 434 individuals demonstrated that the smallest sculpins subsisted primarily on dipteran larvae and small mayflies. These two forms decreased in value as the fish became larger, while the Trichoptera increased in importance. The caddis flies constituted approximately twofifths, dipteran larvae slightly more than onefourth and mayflies about one-fifth of the diet of larger sculpins. These three orders of insects comprised 89.2 percent by volume of the stomach contents of the sculpin, irrespective of size. The three recent papers by Dineen (1951), Zarbock (1951) and Bailey (1952) demonstrate the insectivorous diet of Cottus b. bairdi, Cottus b. semiscaber and Cottus b. punctulatus respectively, and especially the importance of the Diptera, Trichoptera, Ephemeroptera and Plecoptera. Except for Zarbock's paper, there was no distinction between species within the various insect orders regarding their relative importance in the diet of the sculpin. As will be shown in this paper, this is of some importance. I should like to acknowledge my indebtedness to Dr. H. O. Burdick and the Alfred University Research Foundation for their encouragement, and for making funds available to carry out this project. Also I should like to thank the following men for their generous help in identifying some of the aquatic insects: Dr. E. M. Walker, Odonata; Dr. C. Betten, Trichoptera; Dr. S. G. Jewett, Plecoptera; Dr. J. S. Rodgers, Dicranata and Tipula; Mr. A. Stone, Prosimulium. Lastly, I wish to thank my students Wallace F. Henion, Frederick A. Kalber, and John W. Ropes who so willingly put in long hours and endured considerable physical discomfort in the field to complete the work.