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Growth ~ Mean annual growth rates of Westwater Canyon humpback chub (1992-2000) were compared with respect to the bimodal and trimodal distributions of size classes determined from the length- frequencyhistograms. Mean annual growth rates were 10.58 ~ 1.92 mm for humpback chub less than 285 mm and 5.84 f 1.87 mm for humpback chub greater than 285 mm. Humpback chub mean annual growth was 10.15 ~ 2.94 mm for individuals less than 260 mm, 7.70 f 1.90 mm for ~ individuals between 260 mm and 320 mm, and 6.14 f 3.11 mm for individuals greater than 320. Analysis of the larger data sets from recaptures in 1999 and 2000 indicate a high degree of variability in growth rates within size classes between years relative to growth rates from all recaptured individuals between 1992-2000 (Figure 4). ~ Movement Movement of humpback chub determined from long-term recaptures (individuals tagged in previous years) varied from 1998 to 2000. However, through the entire study,. 80% of recaptures exhibited no net movement. There were 371ong-term recaptures of humpback chub in 1998. These individuals ~ had been tagged in the period 1--6 years prior to 1998.Of the 37 recaptures, 17 (45.9%) were recaptured in the same location, 17 had moved from Cougar Bar (RM 121.5) to Miners Cabin (RM 124.1), and three had moved from Hades Bar (RM 120) to Miners Cabin. Only three of these humpback chub had been captured in 1997. One additional humpback chub was tagged in Black Rocks (RM 136) in August 1998 and recaptured at Miners Cabin in October of the same year. In 1999, there were 44 long-term recaptures of humpback chub that had been initially captured in the ~ previous 1-8 years. Of those, 39 (88.6%) were recaptured in the same location, two had moved from Hades Bar to Cougar Bar, one had moved from Cougar Bar to Hades Bar, one had moved from Miners Cabin to Cougar bar, and one was recaptured in October at Miners Cabin that had moved from Black Rocks, where it had been tagged in September 1998. In addition, twenty-six of these 44 Iong-term recaptures were captured in 1998. The final year (2000} resulted in the recapture of 65 ~ humpback chub that had been previously captured in the preceding 1-8 years. Of these 65 long-term humpback chub recaptures, 60 (93.8%) were recaptured in the same location, three had moved from Hades Bar to Cougar bar, one had moved from Cougar Bar to Hades Bar, and one had moved from Black Rocks since its original capture in 1999. The 651ong-term recaptures in 2000 resulted in 30 individuals that were captured in 1999 and 23 individuals that were captured in 1998. s Comparison with ISMP The historic (1988-2000) ISMP catch per unit effort for humpback chub in Westwater Canyon indicates a decreasing trend (Figure 5). The slope of this decreasing trend significantly departs from . zero (p < 0.05). Mean catch per unit effort between 1988 and 2000 as per ISMP sampling protocol was significantly different among years (p < 0.05; Kruskal-Wallis). Furthermore, the distribution of catch rates around the mean was significantly different among years (p < 0.05; Kolmogorov- Smirnov). Length-frequency analysis of humpback chub (>_ 150 mm) data collected via ISMP protocol from ~ 1988-2000 indicates frequent shifts in size structure (Figure 6). Humpback chub in Westwater Canyon appear to move through several types of multi-modal size distributions from year to year. ~ 6