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tagging Colorado squawfish in the upper reach (see Fig. 1) in spring of 1990 but did not conduct systematic searches. Beginning in 1991, three passes through the upper reach were made each spring. With each pass, we netted every backwater that might contain subadult or adult Colorado squawfish. A pass generally took 7-9 days to complete. Capture and tagging efforts in the lower reach began in 1991. There, one pass was made the first spring and two passes each spring during 1992-1994. In some portions of both reaches where backwater habitats were rare, shorelines were electrofihhed with a 5-m, electrofishing boat equipped with a variable voltage pulsator (Coffelt WP- 15) using pulsed DC current. Captured Colorado squawfish were scanned for the presence of a passive integrated transponder (PIT) tag. If none was found, we implanted a PIT tag (Biomark, Inc., Boise, Idaho) in the body cavity using a hypodermic needle after fish were anesthetized with Tricane methanesulfonate. The insertion site for the tag was 2-5 mm posterior to the base of the left pelvic fin. Maximum total length (TL), as defined by Anderson and Gutreuter (1983), was measured (+/- 1 mm). Fish were weighed with an electronic balance (+/- 1 gram) and released after recovery from the anesthetic. We compared movement patterns among 100-mm size groups of Colorado squawfish and between those fish initially captured in the lower reach and those initially captured in the upper reach. To differentiate between localized movements and more substantial dispersal movements, we used as a criterion an arbitrarily defined minimum distance between capture. sites: a distance < 10 km was considered a localized movement; a distance z 10 km a dispersal movement. Data from previous radiotelemetry studies indicated that most adults moved < 7 km during the non-spawning period (USFWS unpublished data). To compare mean distance displaced among size classes of fish, we used ANOVA on In transformed data (transformations were made to equalize variance within cells), and made multiple comparisons (Tukey-Kramer test). Comparisons between percentages of upstream and downstream movements were made using test-of-proportions. For the movement analyses, only displacements one or more years apart were used; no within- year capture-recapture data were used. This allowed fish adequate time to disperse between captures. Also, captures during spawning periods and during pre- and post-spawning migratory periods were excluded so that temporary spawning movements would not be confused with dispersal movements. Sampling was conducted from mid-April to mid-June during spring run-off. Concurrent radiotelemetry studies indicated that annual spawning movements did not commence until late June. The exception to this was 1994 when Colorado squawfish moved to spawning locations in mid-June, presumably due to early warming of water from unseasonably low water conditions. Thus, fish marked or recaptured in 1994 during the month of June were excluded from the analyses. During other years, captures through June 16 were included. Colorado squawfish capture data from other studies were also included in our analyses when they met our criteria. Additional capture data from Stratum 5 was provided by Colorado B-4