Swimming performance of walleye (Stizostedion vitreum) from a wild populati
on was measured relative to fork length (0.18-0.67 m) and water temperature
(5.8-20.5%C), to provide models for setting water velocities in fishways a
nd culverts. Ucrit(60) (the highest speed maintainable for 60 min) values r
anged from 0.30 to 0.73 m/s and increased significantly with length and tem
perature. Ucrit(10) (the highest speed maintainable for 10 min) values rang
ed from 0.43 to 1.14 m/s and also increased significantly with fish length
and water temperature. When startled, walleye were able to attain higher sp
eeds (1.60-2.60 m/s) during short (temperature-independent) bursts of swimm
ing activity. The relatively low Ucrit(60) values suggest that walleye poss
ess a narrow scope for aerobic activity compared with other species, which
may account for their poor performance in fishways. However, the small diff
erences between Ucrit(60) and Ucrit(10) values and the large differences be
tween Ucrit(10) and fast-start performance suggest that low passage efficie
ncy may be caused by a behavioural disinclination to switch from low to hig
h intensity activity.