2004 AFS Meeting Abstracts:

 

Steinhart, G.B., E.A. Marschall, and R.A. Stein. Managing smallmouth bass in a changing world: effects angling and

        exotic species on smallmouth bass reproductive success. Presented at the 134th Annual Meeting of the American

        Fisheries Society, Madison, Wisconsin, August 22-26, 2004.

 

Abstract:

 

We used an individual based model of smallmouth bass Micropterus dolomieu to explore how angling, exotic nest predators round goby, Neogobius melanostomus, and male nest-guarding behavior affected the way fishing regulations influenced reproductive success in two different systems: Lake Erie, Ohio, USA, and Lake Opeongo, Ontario, Canada. This model assumed smallmouth bass made nest-guarding decisions that optimized their lifetime fitness under historical conditions in each lake. As fishing pressure increased, offspring production declined in both systems. However, responses to regulation changes (e.g., seasonal closures, catch-and-release, and size-limits) varied by lake because of lake-specific nest-guarding behavior and population demographics. For example, high adult survival in Lake Opeongo caused males to devalue success of current broods and to abandon more offspring than males in Lake Erie. When we allowed individuals to evolve new optimal behaviors in response to fishing pressure and nest-predators, males abandoned fewer offspring than when following old, sub-optimal behaviors; however, juvenile production remained constant because of high offspring mortality due to storms and natural mortality. We conclude that differences in optimal nest-guarding behavior, resulting from population-specific demographics, played a significant role in success of angling regulations, but behavioral changes within lakes had only a small effect on offspring production.

 

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Collingsworth, P.D., R.A. Oster, C.W. Hickey, R.C. Heidinger, and C.C. Kohler.  Establishing water willow to

        enhance reservoir habitat. Presented at the 134th Annual Meeting of the American Fisheries Society, Madison,

        Wisconsin, August 22-26, 2004.

 

Abstract:

 

Aquatic vegetation performs a variety of functions in the littoral zone of lentic ecosystems. However, large or newly constructed reservoirs often lack submergent vegetation due to fluctuating water levels, high inorganic turbidity, inhospitable bottom sediments, etc. We evaluated the potential of an emergent macrophyte, water willow Justicia americana, for introduction into Rend Lake, a large, unvegetated reservoir in southern Illinois. We transplanted water willow over two years into sites varying in physical conditions and using a variety of different propagule types. In general, we found that water willow transplanted early in the summer had better survival than transplants conducted later in the summer. We also found that rooted propagules had significantly higher first year survival and ultimately exhibited increased growth in newly established colonies. Lastly, we found that shoreline slope was not significantly related to first-year survival of water willow, but did have a significant influence on survival of plants following winter dormancy. Our results illustrate the potential of water willow as a transplant species for reservoir enhancement and highlight some logistical considerations that should be addressed.