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Subadult-Adult Colorado Squawfish The Subadult-adult portion of ISMP has revealed several major changes in the Colorado Squawfish population of the upper basin. The most important has been the large year class spawned in 1986 currently recruiting into the adult population of the Green River and, to a lesser extent, the Colorado River. Mean river-wide catch rates have increased in both rivers as a result of this strong cohort. In addition, increased numbers of adult Colorado Squawfish were collected from the White River downstream from Kenney Reservoir in 1989-1992. These fish were apparently artificially concentrated below the reservoir because they could no longer move upstream to occupy habitat available to them before the dam was built. Catch rates in the Yampa River declined in the middle yeazs of ISMP and increased recently. Whether this indicates a population decline and subsequent rebound is not cleaz. The 1986 cohort corresponds to the highest catch rate observed during YOY Colorado Squawfish monitoring in the Colorado River. Although CPE in the Green River was moderately high in 1986, the highest CPE of YOY Colorado Squawfish there occurred in 1988. Although more common after their first summer of life, the 1988 yeaz class is less common as late juveniles than the 1986 cohort. Young adults and late juveniles (i.e. 350-450 mm long) were captured from the Green, Colorado, and White rivers during most years of ISMP. This indicates some recruitment into the adult populations during most yeazs, although at a lower rate than is currently occurring with the 1986 year class. No fish smaller than 400 mm long was collected from the Yampa River; however, small adults were captured in most yeazs indicating recruitment there as well. Although there was some recruitment to the adult population in most yeazs, no other yeaz class has been as successful as the 1986 cohort. Razorback suckers were captured from the Green River every yeaz, but catch rates declined considerably in recent yeazs. Only one razorback sucker was captured in the White River and one was collected from the Colorado River-none were captured from the Yampa River. The basin-wide trend for the razorback sucker population is down. Abundance of introduced predators that aze monitored with ISMP has been vaziable. Northern pike were very abundant in the Green River during eazly yeazs of ISMP, but they have declined recently. Their abundance in the Yampa River has fluctuated, but they were more common than Colorado Squawfish in many yeazs. Smallmouth bass were also abundant in some reaches during some years, but CPE for this species was extremely vaziable. The subadult-adult monitoring program has successfully detected important trends in the Colorado Squawfish population of the upper basin. However, consideration should be given to several recommendations that could improve the quantity and quality of data collected. A major criticism of ISMP has been the relatively low numbers of Colorado squawfish that aze collected in some rivers during some yeazs. The low numbers of fish prevent an adequate assessment of the population structure every yeaz. A technique involving trapping fish in quiet-water habitats is often more efficient at collecting Colorado Squawfish than ISMP's shoreline electrofishing. However, this technique is not effective in ali reaches in all years. Another important criticism is that ISMP ignores important elements of the fish community that should be included in monitoring efforts. There aze a number of ways of addressing these concerns, but most of the potential modifications will include increased time or manpower requirements that must be considered before any changes aze made. Some potential modifications to ISMP include: (1) discontinuing shoreline electrofishing and viii