Critical Current Speeds for Young Gulf Coast Walleyes

Abstract
We evaluated critical current speeds (CCS, cm/s) for young Gulf (of Mexico) Coast walleyes Stizostedion vitreum and compared the results to field determinations of water velocity under different flood conditions in Luxapalila Creek, Mississippi, which supports a small population of this species. Critical current speeds for actively feeding walleyes ranged from 8 to 74 cm/s, and were related to fish standard length (SL, mm) by log10(CCS) = −0.231 + 0.927·log10(SL), for which P < 0.0001, r 2 = 0.67, and N = 83. Mean current velocities in Luxapalila Creek between May and June ranged from 20 to 45 cm/s. Means were higher than the CCS for a young walleye at that time, but velocities were spatially variable. Persistance of walleyes in Luxapalila Creek and similar streams probably depends on the availability of instream structures that locally reduce current speed. Removal of such structures or channelization of such streams could compromise the survival of a genetically unique southern population of wa...