Growth of selected fishes in Pool 8 of the UMRr:  A test of the flood-pulse concept


Bartels, A. D.  1995.  Growth of selected fishes in Navigation Pool 8 of the Upper
Mississippi River:  A test of the flood-pulse concept .  M.S. thesis submitted to the
faculty of the graduate school of the University of Wisconsin-La Crosse, December
1995.  Reprinted by U.S. Geological Survey, Environmental Management Technical
Center, Onalaska, Wisconsin, January 1997.  LTRMP-97-R001.  63 pp.  (NTIS
 #PB97-144117)


ABSTRACT

Size-specific growth of bluegill, black crappie, and freshwater drum was significantly
different over four years in Navigation Pool 8 of the upper Mississippi River. 
Differences in growth were positively related to annual hydrographs for bluegill but less
related to hydrographs for black crappie and freshwater drum.  These results are
consistent with predictions of the Flood Pulse Concept.  Extensions of  analysis of
covariance (ANCOVA) models were used to account for differences in growth due to
the size of fish and tested for annual differences in growth rates.  Planned comparisons
examined differences in growth among years with a large flood event, two years of
normal hydrology, and a drought.  Some sizes of bluegill and freshwater drum, but not
black crappie, grew significantly faster during the flood year than during years of
normal flow.  Some sizes of bluegill and black crappie grew slower during the drought
year when freshwater drum were not sampled.  Growth curves for bluegill and black
crappie indicate that the magnitude of the effects on growth rate  was greater for the
drought year than for the flood year.  Differences in growth rate among years were most
apparent for bluegill from 50 - 100 mm, black crappie greater than 200 mm, and drum
longer than 100 mm.  These data suggest that (1) patterns in growth for some riverine
fishes are  consistent with the Flood Pulse Concept, (2) droughts may be of greater
consequence than floods to riverine communities, and (3) growth responses related to
hydrology are size- and species-specific.


KEYWORDS

black crappie, bluegill, fish growth rates, flood pulse concept, freshwater drum, Upper
Mississippi River