GROWTH AND HABITAT USE OF FISHES IN THE UPPER MISSISSIPPI
RIVER

Kelly M. Vitcenda and Michael D. Delong
Large River Studies Center, Biology Department, Winona State University,
Winona MN 55987

Habitat diversity is important to fishes because many species use more than one
habitat for feeding and spawning.  In addition to providing multiple habitats for a
given species, habitat diversity allows for greater diversity of fish species through
greater availability of niches.  Seasonal changes in habitat use and size
distribution of fish within different habitats were examined among  three time
blocks: early spring , mid-summer, and early autumn. Fish were collected with an
electrofishing boat along randomly selected segments of backwater, side channel,
and main channel shoreline in Pool 6 of the upper Mississippi River.  Length,
weight, and species were recorded for each fish collected.  Species lists were
examined to establish levels of preference for habitat types. Analysis of
covariance was performed to determine if size distribution, as a measure of
growth, differed for species using more than one habitat.  ANCOVA tested for
differences in weight for a species between habitats with fish length as a
covariate.  Little species overlap was found between backwater and main channel
habitats; however, there was considerable overlap between these two habitats and
side channels.  Shorthead redhorse (Moxostoma macrolepidotum), emerald shiner
(Notropis atherinoides), and smallmouth bass (Micropterus salmoides) were
predominant in the main channel and side channels. Bluegill (Lepomis
macrochirus), emerald shiner (Notropis atherinoides), northern pike (Esox lucius),
yellow perch (Perca flavescens), and walleye (Stizostedion vitreum) were found in
combination between backwater and side channel habitats.  There were no
significant differences in size distribution of fish except for the emerald shiner,
which exhibited greater biomass in the main channel.  This is consistent with the
fact that emerald shiners are known to prefer higher current velocities. 
Similarities in size distribution and species of fish in side channels compared to
fish in the  backwater or main channel suggests that side channels serve as
intermediates between distinct backwater and main channel habitats, increasing
overall habitat diversity of the ecosystem and potentially enhancing riverine
productivity.

Keywords: fish, habitat heterogeneity, growth, side channels, Pool 6


Kelly Vitcenda, Large River Studies Center, Biology Department, Winona State
University, Winona, MN 55987; 507-457-2458; FAX 507-457-5681;
mdelong@vax2.winona.msus.edu

Poster presentation only; student author