Life History Studies of the Spottail Shiner of Clear Lake, Iowa, with Particular Reference to Some Sampling Problems

Collections of spottail shiners, Notropis budsonius hudsonius, were made by systematic seining in Clear Lake from 1956 to 1958. Spottails made up 4.7 and 8.5 percent of the total number of fish caught in minnow seine hauls during the summers of 1956 and 1957 respectively. For this reason, it is believed that the spottail shiner is not of major importance as a forage fish in Clear Lake. Young of the year comprised 80, 47, and 74 percent of the spottail catch in 1956, 1957, and 1958 respectively. Growth was determined from length frequency and from scale analysis. Scales were formed when the spottails were 18 to 20 millimeters in total length. The body‐scale relationship had an intercept of 14 millimeters. Average daily growth increments of young‐of‐the‐year spottails in the summers of 1956, 1957 and 1958 were 0.52, 0.69 and 0.65 millimeters per day respectively. Higher temperatures were related to faster growth. The growth rate of minnows of the 1956 year class from October, 1956 to June, 1957 was 0.022 millimeters per day and during the second summer was 0.18 millimeters per day. Weighted mean lengths of the spottails at the formation of their first, second, and third annuli, were 76.9, 98.2 and 107.9 millimeters respectively. A sub‐sampling scheme was used in the growth analysis. The spottails were collected more frequently at locations where moderate amounts of emergent and submergent vegetation were found. Spottails fed on a wide variety of materials which included water mites, Diptera larvae and adults, Tricoptera larvae, Cladocera, grass seeds and plant fibers. A moderate infection of black grub (Neascus nolfi and a diplostomum type) was found in only one sample of spottails.