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' _ . ~ 6 . ~ Definitive tests were made with appropriate concentrations ascertained in range-finding tests to bracket the 96-hour LC~0 of each chemical using postlarval, juvenile and subadult squawfish at 17 C. A control "snd at least five concentrations of toxicant in a geometric series were used' More bioassays were made, as necessary, so that a LC 50 and 95~ confidence limits could be calculated with reasonable accuracy. ' While computer analysis andfor the methods of Litchfield and Wilcoxon (1949) were to be used for the computation of the LC~Os (concentrations producing 50x mortality) and 95~ confidence intervals, none has been done as yet. Regressions were drawn and inspected far each set of data.. The LCD, LCSO and LC100 values were derived by inspection. The number of duplicate bioassays that might have to be run with both Colorado and northern squawfish ' to permit reliable interspecific comparisons will depend on the magnitude of differences in their tolerances to a chemical. This is an unknown that may have to be considered as bioassays progress. An example is provided in Appendix Z of this regart to help explain the com utational and fractioning procedures that-have been used for the p bioassays conducted thus far. ' Logistics i The general research plan was to test Colorado squawfish with the I6 chemicals previously de cribed. Since no Colorado squawfish has been ! available for bioassay, the northern squawfish has been used exclusively to i date. Availability of this species is somewhat limited to June through October, Consequently, our efforts with the project Leave been to generate as much data as possible while the fish have been available through the summer months. sy doing this we hoped to save time in finding the toxicity levels to test tie ~~3.oradre acP'~awfish wren suff3cicnt numbers became available in October.