Environmental Relationships to Wadeable Stream Fisheries Resources in Mississippi

Wadeable streams in Mississippi do not garner the attention of most anglers or fishery managers; consequently, these streams hold an unmanaged recreational fishery. However, they can support quality sizes and abundances of largemouth bass (Micropterus salmoides), spotted bass (Micropterus punctulatus), and sunfishes. We used the U.S. Environmental Protection Agency’s Wadeable Stream Assessment (WSA) to identify local and landscape-scale environmental features of Mississippi wadeable streams associated with relative abundances and size structure of catchable basses and sunfishes. In addition, we developed a testable regression model that can potentially be used as a rapid assessment tool to locate candidate streams in Mississippi that support a bass and sunfish fishery. Canonical correspondence analysis (CCA) suggested that increases in relative abundances of largemouth bass, longear sunfish (Lepomis megalotis), total bass combined and total sunfish combined were associated with small, meandering stream channels with residual pools, heavily forested watersheds and riparian canopy cover, and poor rapid habitat scores. Increases in relative abundances of spotted bass were associated with increasing stream size, flow and nitrogen concentration, decreases in channel incision height and sand substrates in favor of gravel and wood, as well as benthic macroinvertebrate assemblages with increasing proportions of scrapers and decreasing proportions of collector-gatherers and collector-filterers. These local-scale characteristics reflect forested riparian zones that minimize erosion and sedimentation from landscapes and supply woody debris for invertebrate colonization. In contrast, increases in bluegill (L. macrochirus) relative abundances were associated with more impacted systems, especially large, straight channels with open canopies, increased nutrient runoff, and landscapes with small to moderate increases in agricultural and urban cover (1-18% of watershed area). Our regression model suggests that, on average, as one proceeds towards the Mississippi Gulf Coast and 30 m wide riparian corridors are covered by increasing proportions of forest, then relative abundances and growth of age-1 of basses and sunfishes tend to increase. If this model can be validated, then fishery managers can use the model as a first-order assessment of wadeable streams in Mississippi with regard to their potential to support a recreational bass and sunfish fishery.