Title page for ETD etd-1111102-124457


Type of Document Master's Thesis
Author Mason, Torrance D.
Author's Email Address tmason2@lsu.edu
URN etd-1111102-124457
Title The Influence of Hydrilla Infestation and Drawdown on the Food Habits and Growth of Age-0 Largemouth Bass in the Atchafalaya River Basin, Louisiana
Degree Master of Science (M.S.)
Department Forestry, Wildlife, and Fisheries
Advisory Committee
Advisor Name Title
William E. Kelso Committee Chair
D. Allen Rutherford Committee Member
James P. Geaghan Committee Member
Keywords
  • Atchafalaya basin
  • food habits
  • drawdown
  • hydrilla
  • largemouth bass
Date of Defense 2002-11-01
Availability unrestricted
Abstract
I compared diets and growth rates of age-0 largemouth bass in the Atchafalaya River Basin (Basin), Louisiana, to determine how hydrilla Hydrilla verticillata densities and drawdown influence bass food habits and growth. To assess hydrilla density effects on diet, I compared food habits of age-0 bass collected in high, intermediate, and low hydrilla densities, as well as in Henderson Lake, a semi-isolated portion of the Basin subject to drawdowns in 2001 and 2002 to reduce hydrilla densities. I also compared diets of age-0 bass from sites sampled in 2001 and 2002 that were also sampled in the mid-1970s before hydrilla had colonized the Basin. Frequency of occurrence and percentage of the diet by weight composed of fish prey consistently decreased as hydrilla coverage increased. Bass switched to a more fish-dominated diet sooner in Lake Henderson after the 2001 drawdown, but the importance of fishes in the diet decreased quickly as hydrilla beds became re-established. Effects of the 2002 drawdown in Lake Henderson lasted much longer, and age-0 bass switched to a piscivorous diet sooner and maintained a more fish-dominated diet throughout the spring and summer relative to bass collected from hydrilla-infested areas of the Basin. Length frequencies and mean length in August revealed smaller bass in areas affected by high hydrilla densities, however, there was no evidence that drawdown resulted in a growth advantage for age-0 largemouth bass. Mean length and weight of age-0 largemouth bass was significantly lower in areas supporting high hydrilla densities compared to habitats with intermediate and low hydrilla abundance. Results indicate high hydrilla coverage has major effects on the diet of age-0 largemouth bass, and those effects are reflected in reduced growth of individuals inhabiting high-density hydrilla beds.
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