7760

• UCREFRP Catalog Number: 7760
• Author: Beyers, D. W., R. T. Muth and M. S. Farmer.
• Title: Experimental Evidence of Competition Between Larvae of Colorado Squawfish and Fathead Minnow.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

(Figure 2). Relative growth of Colorado squawfish was less than that of
fathead minnow in all experimental treatments.
Intersaecific exploitative competition
Negative effects of interspecific competition were greater for Colorado
squawfish than for fathead minnow. One-sample t-statistic comparisons showed
that Colorado squawfish grew significantly slower in four of nine
mixed-species treatments than in single-species assemblages (Table 1). Of the
remaining five mixed-species treatments, four had non-significant negative
effects on Colorado squawfish growth. The 25:75, 32 zooplankton•fish~'•day~'
experimental treatment was the only one in which Colorado squawfish growth was
not negatively affected; however, this response was not significantly
positive, suggesting that growth in mixed- and single-species assemblages may
have been equivalent. In contrast to Colorado squawfish, fathead minnow
growth was significantly reduced by competition in only one experimental
treatment. Of remaining mixed-species treatments, three had non-significant
negative effects and five had non-significant positive effects on fathead
minnow growth.
Inspection of tabulated d values showed that significant responses did
not occur more or less frequently as a function of relative abundance or
feeding regime (Table 1). There was a weak tendency for non-significant
positive values at low feeding regimes, and non-significant negative values at
high feeding regimes. No consistent trends were apparent within feeding
regimes. However, t-tests are inadequate for detection of quantitative
relationships within data sets (e.g., d as a function of relative abundance)
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