The fish populations in Clear Lake, in north central Iowa, are being studied annually by various members of the Iowa Cooperative Fisheries Research Unit to determine the changes in species composition, growth rates, condition, year class abundance, and other measures of value in fisheries biology (Bailey and Harrison, 1945; Lewis and Carlander, 1948; Cleary, 1949; Carlander and Cleary, 1949). In connection with these investigations, experimental gill nets were set in various parts of the lake. Since the nets were usually lifted at two-hour intervals, the times at which the fish were caught were recorded, thereby giving a measure of the activity of the fish at various periods. It is recognized that there may be several errors which may arise in the use of gill net catches as measures of activity, but the results in most cases are clear enough that the errors are probably of little significance. In some cases there was doubt as to whether the gill net catches indicated activity or merely local concentration of the fish.
Proceedings of the Iowa Academy of Science
©1950 Iowa Academy of Science, Inc.
Sieh, James G. and Parsons, John
"Activity Patterns of Some Clear Lake, Iowa, Fishes,"
Proceedings of the Iowa Academy of Science, 57(1), 511-518.
Available at: https://scholarworks.uni.edu/pias/vol57/iss1/74