Revised Predictive Model for Successful Introduction of Native Ohio Brook Trout (Salvelinus fontinalis) in Select Streams in Geauga and Lake counties, Ohio12/19/2014
Eight cold-water streams in Lake and Geauga Counties, Ohio were evaluated to revise a predictive model for assessing streams for future introduction of threatened native Ohio brook trout (Salvelinus fontinalis). A 15-month study was conducted in streams where brook trout were previously introduced during the years 1997-2002. Fifty percent of the 16 original reintroduction streams failed to support the establishment of self-sustaining populations of brook trout, indicating there were additional factors contributing to their success and failure. Of the eight streams included in this study, four streams were designated successful, two variable, and two failed in terms of the brook trout’s ability to establish self-sustaining populations as defined by the Ohio Department of Natural Resources (ODNR). Multivariate statistical methods including principal component analysis (PCA) and agglomerative hierarchical cluster analysis (AHCA) identified the most important characteristics in brook trout stream selection. Factors found to be statistically significant for brook trout success include: 1) stream velocities within the range of 1.4 to 4.7 cm/s; 2) high hydraulic conductivity of the headwater bedrock aquifer (K>4.7 x 103 cm/s); 3) lighter average δ18O ‰ (-9.8 to -10.4); 4) either high percent canopy cover (40 percent to 55 percent) or high percent instream cover (18 to 37 percent); 5) abundant cold-water adapted benthic macroinvertebrate taxa (10 to16 species); 6) yearly average hyporheic water temperature of 4.6°C to 17.2°C; and 7) average surface water turbidity of 7 to 31 NTU. Long-term surface water temperature and dissolved oxygen monitoring over both winter and summer seasons is recommended prior to brook trout introduction to ensure their sustainability.