M. T. DRISCOLL AND H. L.
SCHRAMM, JR., Mississippi Cooperative Fish and Wildlife Research Unit, Mississippi
State University, P.O. Drawer BX, Mississippi State, Mississippi 39762, USA
The U.S. Army Corps of Engineers maintains a
commercial navigation channel in the Lower Mississippi River by managing water flow with
rock wing dikes and bank paving (revetments). Revetments prevent the river from carving
new channels in the alluvial plain. Wing dikes, by diverting flow, accelerate
sedimentation of downstream secondary channels and loss of aquatic habitat. Losses of
secondary channel habitats may hold important ecological implications. We compared the
abundance of catfishes (Ictalurus furcatus, I. punctatus, and Pylodictis
olivaris) in shallow sandbar and steep bank habitats at two main channel and four
secondary channel locations in the Lower Mississippi River by sampling with electrofishing
from August to December 1994. Electrofishing indicated numbers of all three catfishes were
significantly (P < 0.10) higher in main channel habitats in August, whereas numbers of
channel catfish and flathead catfish were significantly higher in secondary channel
habitats in October. Our results do not support a unique need to maintain secondary
channel habitats, but secondary channels seem to provide beneficial habitat for catfishes
at certain river stages. We conclude that important catfish habitat would be lost if
sedimentation eliminated the secondary channels. |
