Temporal and spatial trends of Upper Mississippi River fish

Kirby, D. J., and B. S. Ickes. 2006. Temporal and spatial trends in the
frequency of occurrence, length–frequency distributions,
length–weight relationships, and relative abundance of Upper
Mississippi River fish. U.S. Geological Survey, Upper Midwest
Environmental Sciences Center, La Crosse, Wisconsin, July 2006.
LTRMP 2006-T002. 68 pp

ABSTRACT

The Long Term Resource Monitoring Program (LTRMP) collected
more than 24,000 fish community samples from six study areas on the
Upper Mississippi River System in 1993–2002. More than three
million fish comprised of 136 fish species were collected. These data
were used to assess lengthweight relations and size structure of
commercial (i.e., commercially harvested) and recreational (i.e.,
recreationally harvested) species, and the distribution, frequency of
occurrence, and abundance patterns of commercial, nongame (i.e., not
commercially or recreationally harvested), and recreational species.
Fortyseven species were collected in all six LTRMP study areas, 32
species were collected in 4 or 5 study areas, 33 species were collected
in 2 or 3 study areas, and 24 species were collected in 1 study area.
Spatial differences (i.e., differences among study areas) in size
structure were more pronounced for commercial species than for
recreational species. Rate of gain (increase in log10 weight per unit
increase in log10 length) was assessed for five species, and was
significantly different among study areas for all five species and
significantly different among years for four species. Assessment of
longitudinalspatial (among study area), lateralspatial (among aquatic
area types) and temporal (among 10 years) patterns in abundance
showed that species were most similar with respect to temporal
variation in abundance, and least similar with respect to
longitudinalspatial variation in abundance. These fisheries population
assessments, derived from the spatially and temporally expansive
LTRMP dataset, will provide river resource managers with decision
support tools for managing UMRS fisheries.

KEYWORDS

Abundance patterns, fish populations, Illinois River, lengthweight
relations, size structure, species richness, Upper Mississippi River