Effects of a Large-scale Habitat Enhancement Project on Largemouth Bass Behavior, Feeding, and Growth in Grand Lake, Texas

The quality of habitat, or the environment suitable for an organism to survive and reproduce, is often described by the type of features present and the quantity and condition of such features. Habitats in many ecosystems are declining and the loss of important habitats likely affects the success of organisms reliant upon those features. Habitats in reservoir ecosystems are especially at risk because of aging processes that are degrading reservoir habitats at faster rates than habitats in other ecosystems. Habitat enhancement projects are one tool used to combat the effects of aging reservoirs but the benefits of these management actions to sportfish populations are poorly understood. We evaluated the effects of a large-scale habitat enhancement project on Largemouth Bass movement behavior, feeding, and growth in an aging reservoir in eastern Texas. To understand behavioral responses, we compared adult Largemouth Bass habitat selectivity, daily movement rates, and seasonal use area sizes before and after the habitat enhancement project. Adult Largemouth Bass behavior changed following the large-scale habitat enhancement project. Although Largemouth Bass selected areas with structural features during both study periods, they selected strongly for areas with newly added habitat. Largemouth Bass daily movement rates and seasonal use area sizes remained similar to those observed before the addition of habitat. We also compared growth rates and diets of Largemouth Bass following the habitat enhancement project. Largemouth Bass growth increased following the addition of structural habitat, which resulted in a predicted increase in growth of 120 mm (TL) at age 5. Largemouth Bass diets (calculated as mean percent composition by wet weight) did not change following the addition of structural habitat, and often included large amounts of fish. Changes in Largemouth Bass habitat selectivity and growth in response to the addition of structural habitat may be the result of an improved foraging environment that facilitates increased consumption rates by Largemouth Bass. Habitat enhancement projects, such as adding structural features, may increase production of top predator sportfish populations by providing environmental conditions favorable for foraging that facilitates increases in growth.