Cooperative Fish and Wildlife Research Units Program: Arkansas
Education, Research and Technical Assistance for Managing Our Natural Resources

Radiotelemetry techniques and trace element analyses of otoliths have proven to be effective for describing the environmental history of individual salmonids and population dynamics. Rainbow trout Oncorhynchus mykiss were implanted with radio-transmitters within four catch-and-release (CR) areas on the tailwater systems of the White and Norfork Rivers, Arkansas and tracked weekly from summer 2005 to fall 2006. Telemetry data was used to estimate home-ranges based on total linear distance and kernel density estimates. Fish in three areas showed strong site fidelity throughout the course of the study, whereas all fish tagged in the most downstream site died or emigrated from the study area by the spring, correlating with a rise in water temperatures. To determine whether otolith microchemistry data could be used to differentiate between rainbow and brown trout Salmo trutta captured from three of the CR areas, otolith edges were analyzed for comparative analysis. Otolith cores were also evaluated and compared to hatchery fish to determine if any wild reproduction was occurring within CR areas. Otoliths were processed using laser-ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). Radiotelmetry fish known to have remained within their CR areas were recovered and their otoliths were also analyzed. Overall, despite differences found in seven element:Ca ratios in water samples between sites, edge chemistry in otoliths could not distinguish fish from their collection sites with much accuracy, and core chemistry for rainbow and brown trout could not discriminate between hatchery and wild stocks.