Document: TIM-3-72-2

Habitat complexity, predator-prey interactions and the spatial distribution of largemouth bass and its prey.

ESSINGTON, T.E.* ¹, J.F.KITCHELL ¹ and J.R.HODGSON ²

University of Wisconsin, Madison, WI 53706, USA ¹
St. Norbert College. ²

Abstract:
The spatial distributions of predators and prey are dictated by a dynamic game, the outcome of which should vary across spatial scales. We evaluated the correlation between local predator and prey abundances across a range of spatial scales, hypothesizing that predator-prey abundances would be negatively correlated at small spatial scales, but positively correlated at larger spatial scales. We assessed the spatial distribution of largemouth bass (Micropterus salmoides) and its prey (brook stickleback (Culea inconstans) and bass young-of-year (YOY)) in Long Lake, WI. We manipulated littoral habitat by translocating all structure from 20% of the littoral zone (removal zone) and placing it in a distant region of the lake (addition zone), and evaluated fish habitat use and the correlation between adult bass and prey distributions for six 24 hour periods before and after habitat manipulation. Adult bass distributions were assessed by radio-telemetry and prey distributions were assessed by fish traps positioned along the perimeter of the lake. Bass were significantly aggregated at all spatial scales prior to manipulation, but were weakly aggregated after the habitat manipulation. However, this shift did not coincide with the timing of habitat manipulation, and bass preferentially inhabited the removal zone before and after manipulation. Stickleback and bass YOY distributions were negatively correlated with adult bass across all spatial scales. Perch YOY, which were not an important prey item, were either not correlated (pre-manipulation) or were positively correlated (post-manipulation) with adult bass. Surprisingly, structurally complex habitat was not an good predictor of predator or prey abundance. We conclude that predator-prey interactions were important in dictating the spatial distribution of prey and speculate that the high prey abundance in Long Lake made it unnecessary for bass to associate in regions of high prey density. This behavior created a refuge for prey in regions where bass did not commonly inhabit, thereby diminishing the importance of structurally complex habitat.

Keywords: spatial scale; predator-prey interactions; prey refuges

This abstract is being presented at: 3:45 PM in session:
Oral Session #62: Freshwater Fish Ecology.