Swimming performance of the Topeka shiner (Notropis topeka) an endangered midwestern minnow

The Topeka shiner (Notropis topeka) is imperiled by extensive changes in st ream hydrology. Responses of shiners to changes or variation in stream hydr aulics, however, have not been quantified, hampering conservation efforts. We quantified swimming endurance and behavior for Topeka shiners in a labor atory swim tunnel. Sustained swimming (>200 min) was observed at water velo cities of 30-40 cm/s. Prolonged and burst swimming (approximately 10 min to less than 0.1 min) was observed at water velocities of 40-75 cm/s and endu rance was negatively correlated with water velocity. Larger individuals (4. 4-5.5 cm standard length) exhibited greater sustained swimming ability than smaller individuals (3.0-4.2 cm standard length). Oral grasping of wire me sh within the swim tunnel was frequently employed at moderate water velocit ies (35-50 cm/s); this behavior may limit downstream displacement of shiner s during freshers. Topeka shiners are capable of swimming speeds faster tha n water velocities which they typically inhabit. Fishways and culverts, the refore, may be employed to facilitate dispersal and recolonization. Swimmin g endurance data are used to determine optimal size and water velocities fo r such structures.