Date of Award
Master of Science
Natural Resource Ecology and Management
Clay L. Pierce
Growth rates of fish may vary in response to changing environmental conditions and presence of aquatic nuisance species (ANS). Two ANS, common carp and zebra mussels, are present in Clear Lake, Iowa, and may affect growth rates of fish along with other environmental factors. We (1) documented annual growth rates of four fish species in their first year of life and at maturity in Clear Lake, (2) examined relationships of growth with environmental factors, and (3) compared contemporary growth to previous studies. Age-0 black bullhead, common carp, walleye and yellow bass showed a significant, positive relationship with common carp commercial harvest in the previous year and annual number of degree days where water was above 5oC. Chlorophyll a concentration showed a positive relationship with age-0 growth of common carp and yellow bass. Age-0 black bullhead growth was positively related with zooplankton concentration and common carp and yellow bass were negatively related. We saw no significant relationships between environmental variables and annual growth at length-at-maturity. Black bullheads grew similarly in 1955 and this study, but showed slower growth in 1999. Common carp were growing substantially faster in 1952 than in 1999 and the present. Walleye mean length-at-age data collected in this study was similar to the mean length-at-age data recorded in the two historical studies. In the 1940's, yellow bass were growing substantially faster than in the 1960's and currently. Our results demonstrate that growth of all four species has changed over time, that growth varies in response to environmental factors and ANS, and that continued management of common carp by removal may result in faster growth early in the life cycle of several fish species in Clear Lake.
Eric Daniel Katzenmeyer
Katzenmeyer, Eric Daniel, "Fish growth responses to a changing environment: effects of aquatic nuisance species and environmental conditons in a shallow, eutrophic lake" (2010). Graduate Theses and Dissertations. 11827.