LAUSR

Small-bodied fish species are commonly used for the assessment of environmental effects because they are short lived, abundant, and they mature early. Although they are generally considered to be less mobile than larger bodied species, relatively little is known about their movement patterns. In this study, we tagged 3,001 rainbow darters (Etheostoma caeruleum) (≤76 mm) in the upper Grand River of southern Ontario with visible implant alpha tags and elastomers in 3 riffles. Five hundred sixty-five fish were recaptured over 4 recapture events (including spawning and nonspawning periods) over a spatial extent of 1900 m. The rainbow darter demonstrated high site fidelity having a median movement of 5 m and with 85% staying within the riffle in which they were originally tagged. Most movements occurred during the spawning period, where males moved at a greater frequency and had a tendency to move longer distances (up to 975 m). There was also a bias in the direction of movement, which was dependent on the recapture season. Overall, the high site fidelity of the rainbow darter makes it a candidate, sentinel species for the assessment of environmental effects.