In 1996, scientists caused an experimental flood of the Colorado River by releasing water from Glen Canyon Dam above the Grand Canyon. Because an unintentional flood in 1983 had reduced the river’s introduced population of nonnative trout, biologists were concerned that the experimental flood would wash many fish, native and nonnative, downstream. To find out, biologists placed nets in the river. The nets captured a few more trout than they would have without the flood but did not show substantial flushing of native fish, whose ancestors had, after all, survived many larger natural floods. The biologists surmised that the native species (and most of the trout) must have quickly retreated to protected areas along the riverbank.
1. Which of the following, if true, would make the information presented in the passage compatible with the experimental flood’s in fact having caused substantial flushing of native fish?
A. Many of the native fish are too small to have been captured by the nets.
B. There had been and increase from normal levels in the native fish population prior to the flood.
C. The native fish in the Colorado are much stronger swimmers than taxonomically similar fish in other rivers in the region.
D. The unintentional flood of 1983 had not affected the river’s trout population as much as was originally thought.
E. The experimental flood raised the water level much less than a typical natural flood would have.
2. According to the passage, which of the flowing is true of the Colorado River flood of 1983?
A. The flood had a negative effect on the river’s trout population.
B. There was substantial flushing of the river’s native fish population during the flood.
C. Unlike the 1996 flood, it was not deliberately caused for scientific research purposes.