Fish monitoring by the LTRMP on the UMRS, 1990 1994


Gutreuter, S. 1997. Fish monitoring by the Long Term Resource Monitoring Program on
the Upper Mississippi River System: 1990 1994. U.S. Geological Survey,
Environmental Management Technical Center, Onalaska, Wisconsin, November
1997. LTRMP 97-T004. 78 pp. + Appendix  (NTIS #  PB98-116981)


ABSTRACT

The Long Term Resource Monitoring Program (LTRMP) of the Upper Mississippi River
System (UMRS) conducts highly standardized monitoring of fishes in Pools 4, 8, 13, and
26, in a segment of the unimpounded Mississippi River, and in the La Grange Pool of the
Illinois River. The mission of the LTRMP is to provide decision makers with information
for managing the UMRS as a sustainable large river ecosystem given its multiple-use
character. In this report I summarize the initial 5 years of fish monitoring by the LTRMP.
This report documents temporal variability that will be critical to interpretation of future
events and trends (consistent temporal changes), and documents important spatial
patterns. Because 5 years of data can only provide tenuous trend information and because
the LTRMP sampling design was changed between 1992 and 1993, trends reported
herein must be interpreted cautiously. No evidence of reduction of fish species richness
(number of species) was found from 1990 through 1994 or since recording began in the
late 19th century. The abundance of common carp (Cyprinus carpio), an exotic but
commercially harvested species, and sauger (Stizostedion canadense), a recreationally
valuable species, increased dramatically from 1990 through 1994. Few species declined
in abundance. Spatial patterns in the abundance of certain species, including bluegill
(Lepomis macrochirus), largemouth bass (Micropterus salmoides), white crappie
(Pomoxis annularis), and black crappie (Pomoxis nigromaculatus) provide substantial
evidence that the availability of backwaters presently limits the abundance of these
species in the open river study reach, to a lesser extent in Pool 26, and probably
elsewhere. This information could be instrumental in identifying the effects of present
river management practices and predicting some biological and economic consequences
of future changes in floodplain composition. No evidence was found that the relatively
rare lake sturgeon (Acipenser fulvescens), shovelnose sturgeon (Scaphirhynchus
platorynchus), paddlefish (Polyodon spathula), and blue sucker (Cycleptus elongatus)
declined in abundance from 1990 through 1994. The flood of 1993 provided an
opportunity for skipjack herring (Alosa chrysochloris) to temporarily reenter the
uppermost pools of the Mississippi River.


KEYWORDS

Abundance, biodiversity, fish, flood, floodplain, habitat, river, and trend