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? I squawfish ranging in length from 466 to 775 mm, 78 roundtail chub ranging in length from 239 to 414 mm, 106 flannelmouth sucker ranging in length from 172 to 523 mm, 17 bluehead sucker ranging in length from 119 to 401 mm, 46 common carp ranging in length from 384 to 740 mm, and 45 white sucker ranging in length from 133 to 517 mm. Colorado squawfish at 470 mm in length appear vulnerable as prey to about 29 % of the northern pike population. These northern pike would be 570 mm in length and larger (Figure 15). Mid-size Colorado squawfish in the population, based on cross-sectional body area, are vulnerable to only 1.6 % of the northern pike population at sizes > 890 mm. Eight percent of the Colorado squawfish appear invulnerable to any northern pike predation. Using 487 mm as the maximum prey size in reality that would be taken by northern pike, the length frequency distribution of Colorado squawfish indicates 6 % of the population is vulnerable to northern pike predation (Figure 16). Roundtail chub at 240 mm in length appear vulnerable to at least 90 % of the northern pike population at 330 mm or larger (Figure 15). Mid-size roundtail chub are vulnerable to 73 % of the northern pike population > 550 mm in length and the largest roundtail chub was vulnerable to 22 % of the northern pike > 560 mm in length. Based on roundtail chub length frequency data and the 487 mm prey size maximum, 100% of the population appears vulnerable to northern pike predation (Figure 16). Bluehead sucker at 120 mm and flannelmouth sucker at 170 mm were both vulnerable as prey to at least 95 % of the northern pike population (Figure 17). Overall, bluehead sucker appeared more vulnerable than flannelmouth sucker to northern pike predation due to the relatively smaller average and maximum size of bluehead suckers in the population. For bluehead sucker, potential northern pike predators were 220 mm or larger; and for flannelmouth sucker, potential northern pike predators were 270 mm or larger. Mid-size bluehead sucker appear vulnerable to 82 % of the northern pike population > 400 mm and the largest bluehead sucker was vulnerable to 38% of the northern pike population > 580 mm. Mid-size flannelmouth sucker appear vulnerable to 27 % of the northern pike population > 600 mm, and the largest flannelmouth sucker were vulnerable to only 1.6% of the northern pike population > 840 mm in length. Based on length frequency distribution and the prey size cap of 487 mm, 100% of the bluehead sucker and 82% of the flannelmouth sucker are vulnerable to northern pike predation (Figure 16). White sucker at 130 mm in length were also vulnerable as prey to 95 % of the northern pike population (Figure 18). Like bluehead sucker, potential northern pike predators were 220 mm in length or larger. A mid-size white sucker was vulnerable to 19 % of the northern pike population > 620 mm in length. Similar to flannelmouth sucker, the largest white sucker were vulnerable to only 1.6 % of the northern pike population > 840 mm in length. Based on length frequency distribution and the northern pike prey size cap, 96% of the white sucker are vulnerable to northern pike predation (Figure 16). LI DRAFT March 12, 1996 45 1