Background

The smallmouth bass, Micropterus dolomieu, is a popular sport fish that is common in the clear, upland streams of the Ozarks. While smallmouth bass populations found in Arkansas are locally abundant and support a quality sport fishery, its occurrence in the state represents the southern margin of this species' distribution. Numerous static measures of smallmouth bass populations (e.g., density or biomass) appear in the literature and may be of interest for specific applications, but the dynamic measure of production rate is the best indicator of a species' ecological success. Production is a synthesis of population biomass, recruitment, growth, and mortality and is especially responsive to the welfare of a population and environmental change. The methods and terminology for estimating fish production have evolved to a generally accepted convention, and estimates of fish production are becoming more abundant in the literature and are being applied to management problems.

Smallmouth bass production rates from any Boston Mountain Ecoregion population have not been estimated or published, and therefore, it is difficult to identify potential physical or biotic factors that may influence this species' ecological success in this area. Smallmouth bass is the most intolerant species to habitat alteration of any of the black basses (Micropterus spp.) and is especially sensitive to turbidity or siltation. It is presumably affected by land use patterns in associated stream riparian zones and watersheds, but these relationships remain poorly understood.

Objectives

In this study, we combined intensive and extensive surveys to quantify the fish assemblages and ecological success of smallmouth bass in the Boston Mountains of the Ozark National Forest. We estimated annual production of black bass populations and biomass of other fishes and examined the relationship between these population variables and forest management practices. Specific objectives were to:

(1) Survey Boston Mountain streams for abundance of black bass populations and other fish assemblage characteristics;

(2) Select three stream reaches associated with varying land use patterns (timber harvest, agriculture, and wilderness) for detailed estimation of smallmouth bass production rates (including density, biomass, growth, recruitment, and mortality); and

(3) Relate patterns in fish production and assemblages to land use patterns.

Results and Benefits

The results of the extensive sampling provided a generalized distribution of black bass and fish assemblages in the Boston Mountains of the Ozark National Forest. This information will be useful to fisheries managers of the U.S. Forest Service and the Arkansas Game and Fish Commission. The production estimates are the first data of this kind from any fish population in the ecoregion. These results quantified the variation that may occur among populations, and these data were compared to annual production estimates from smallmouth bass populations in other regions. They will provide an ecological basis for management of the species in this region and quantitative information that should be considered when developing angling and harvest regulations. The fish assemblage and production dynamics results may also serve as baseline data to compare with future surveys and estimates at the same locations to assess trends over time.

The findings relating forest management practices or land use patterns to fish production and assemblages have important management implications. These results provide information that will be useful to forest and land managers when approaching management at a broad spatial scale from an ecosystem perspective. Finally, the approach of this research, combining extensive and intensive approaches contributes to the greater understanding of the ecological influences and human impacts on stream fauna from differing spatial scales.

For details of results, see

Rambo, R.D. 1998. Ozark stream fish assemblages and black bass population dynamics associated with watershed of varying land use. Master of Science Thesis. University of Arkansas, Fayetteville. 98 pages.

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