Figure 1. Map of the ONSR depicting the locations of the sampling sites and large springs (1-2 order magnitude). Discussion  SMB > Age-0 abundance is associated with seasonal precipitation totals while LMB > Age-0 abundance is associated with stream size. Suggests shifts in habitat availability may be more important than biotic interactions (competition).  Age-0 SMB increase while Age-0 LMB decrease in abundance with greater distance to a spring. Suggests differences in preferred rearing habitats between the two species and that areas nearer springs may produce conditions (temperature, discharge, etc.) that favors LMB over SMB.  Age-0 LMB abundance decreases with increased SMB > Age-0 abundance and SMB > Age-0 abundance increases with decreased LMB > Age-0 abundance. SMB > Age-0 may limit LMB through biotic interactions. Figure 4. Top models describing Age-0 LMB and SMB with distance to spring, Age-0 LMB with SMB > Age-0, and LMB > Age-0 with wetted width. Figure 2. Length frequency histograms of SMB and LMB used for determining length at Age-0 and > Age-0 (left and right of red line, respectively ) ( data). Figure 3. Top models (or components of the top models) describing SMB > Age-0 catch/minute with winter precipitation and LMB > Age-0 catch/min. Models Winter Precipitation (mm) Spring Precipitation (mm) Summer Precipitation (mm) Fall Precipitation (mm) Total Annual Precipitation (mm) Distance to Nearest Major Spring (km) Mean Winter Air Temperature (°C) Mean Spring Air Temperature (°C) Mean Summer Air Temperature (°C) Mean Fall Air Temperature (°C) Water Temperature at Time of Sampling (°C) Mean Wetted Width (m) Backwater Area Within Reach (m²) Upstream Watershed Area (km²) SMB > Age-0 CPUE (For only LMB models) LMB > Age-0 CPUE (For only SMB models) Mean Winter + Spring + Summer + Fall Air Temperature Mean Wetted Width + Upstream Watershed Area Winter Precipitation + Spring Precipitation + Summer Precipitation + Fall Precipitation Global Using Habitat, Climate, and Competitive Interactions to Predict Co-Occurring Smallmouth Bass and Largemouth Bass in the Ozark National Scenic Riverways Introduction The Ozark National Scenic Riverways (ONSR), in southeast Missouri, supports populations of both Smallmouth Bass Micropterus dolomieu (SMB) and Largemouth Bass Micropterus salmoides (LMB), with SMB dominating. The ONSR are heavily spring influenced (Figure 1), which provides warm- and cold-water refugia in winter and summer, respectively. There appears to be a recent increase in LMB and a concurring decrease in SMB in the lower portion of the river. The reason for these changes are unknown. We will determine what factors drive SMB and LMB abundance in main-channel habitats. This information may help resource managers develop adaptive management strategies to conserve the native fish community. Jacob M. Schwoerer 1*, Skyler H. Schlick 1, Josey L. Ridgway 1, Chris J. Rice 1, Hope R. Dodd 2, and Craig P. Paukert 3 Objective Determine what factors influence the abundance of main-channel SMB and LMB in the ONSR. Methods Data National Park Service Heartland I&M Network used standardized boat electrofishing for fish sampling and measured in-stream habitat at the same seven sites over six years ( ; Figure 1). A Geographic Information System was used to calculate upstream watershed area and Shreve link magnitude. Seasonal mean air temperature and total precipitation data was collected from the Missouri Historical Agricultural Weather Database from Alley and Round Spring locations within the ONSR. Analysis Developed a priori models (Table 1) to predict SMB > Age-0 CPUE, Age-0 SMB CPUE ( Age-0 CPUE, and Age-0 LMB CPUE (<115mm; Figure 2). The model with the smallest Akaike’s Information Criterion value corrected for small sample size (AICc) and models with ΔAICc values of < 2 were equally considered the most predictive model. Table 1. Candidate models used to predict Age-0 and > Age-0 SMB and LMB CPUE using AICc. 1 Missouri Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, University of Missouri 2 National Park Service, Heartland I&M Network 3 U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit Results Table 2. Top models describing Age-0 and > Age-0 SMB and LMB CPUE. Arrows represent direction of the relationship (↑= Positive relationship, ↓=Negative relationship). *Corresponding Author 302 ABNR University of Missouri Cooperative Fish and Wildlife Research Unit Columbia, MO Flow > Age-0 Age-0 Keith Bartlett FISHBIO ModelAICcΔAICcWt. SMB > Age-0Winter Precipitation ↓ (Figure 3a) LMB > Age-0 Abundance ↓ (Figure 3b) Watershed Area ↑ Summer Precipitation ↓ Age-0 SMBDistance to Nearest Major Spring ↑ (Figure 4a) LMB > Age-0Wetted Width ↑ (Figure 4b) Wetted Width ↑ + Watershed Area ↑ Watershed Area ↑ Age-0 LMBDistance to Nearest Major Spring ↓ (Figure 4a) SMB > Age-0 Abundance ↓ (Figure 4c) a b c a b