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the seconds that electrical current was passing through the water. Two passes consisted of one electrofishing raft (Jul 9-12, 1998 and JulI2-14, 1999); the other passes consisted of two electrofishing rafts. Each pass was considered a sample, i.e., two sample passes each year. The standard deviation (SD) and coefficient of variation (CV) was calculated for each year. Simulation techniques were used to determine how well CPUE data would describe population trends. The simulations consisted of starting at t = 1 with a CPUE = 1.00 and annually decreasing the CPUE (assuming CPUE decreases proportionally to the population) by either 0, 1,5, or 10 percent over 5, 10, 15, and 20 years. At the beginning of each year, the CPUE was "measured" by randomly sampling from a normal distribution with a mean of equal to the deterministic CPUE and CV = 0.31 (the average value our data showed for raft electrofishing). At the end of 5, 10, 15, and 20 years the simulated trend data were tested for significant negative slope at the 95% confidence level (one-tailed t-test). Prior to testing, the data were log transformed because the SD is proportional to CPUE. Each simulation was run for 1,000 replications and the number of times a significant decline was detected was counted. Results Humpback chub identification. Field identification of humpback chub and roundtail chub was sometimes difficult, but confidence was gained with experience. The traits most useful for separating adult humpback chub from roundtail chub were the presence of a predorsal hump, subterminal mouth, 10 principal anal fin rays, and narrow caudal peduncle. A few fish had intermediate characters for some traits, and we identified these fish based on our best judgement. 7