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size that the fall-stocked group was when their survival was estimated. Again, a binomial chi-square test will be used to test whether percent survival is equal for the two groups of squawfish stocked at different seasons. METHODS Field Study 1. Study site selection Flooded gravel pits will be investigated not only because of their potential use as controlled rearing areas for squawfish, but also be- cause closed systems are required for effective monitoring of resident fish populations and squawfish survival over time. Although not com- pletely analogous to river backwater habitat, riverside ponds will be used here as study sites for evaluating the interactions among species found in backwater communities. Study ponds will be located in the Grand Valley area of Colorado between Loma and Palisade because survival of YOY Colorado squawfish appears to be especially low in this portion of the fish's range (L. Kaeding, USFWS, personal communication, 1984). Riverside ponds will be located e. using..aerial photographs and then ground-checked for potential use. Those that are under four hectares in size, have vehicular access, and a shoreline conducive to launching a boat will be briefly surveyed to determine fish community composition and basic'limnological features such as depth profile, temperature, dissolved oxygen (DO) content, con- ductivity, and secchi disc transparency. A cursory study using one overnight trammel-net set and three seine hauls will be conducted to evaluate the fish community. Five study ponds will be selected on the basis of differences in fish community composition, provided that there are no limiting abiotic factors present and that landowners are willing to cooperate. Ideally, these ponds will range from one containing a high density of largemouth bass to one containing no bass. Where more than one potential study pond meets the bass density criteria, final selection will be based on differences in forage fish abundance and composition. 31