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e) The age structure for brown trout has also shifted to a larger percentage of older fish. Ages 1-5 changed by 30%, 9%, 67%, 205% and 423%, respectively. The Pick Bridge station is approximately 23 miles downstream of the Treasure Island station. Rainbow and brown trout population trends at the Pick Bridge station revealed that there are no statistically significant differences between years. Current sampling efforts in this area will be directed away from spring sampling and towards early fall sampling to try and reduce the impact of early spring rainbow trout spawning and late fall brown trout spawning which bias the estimates. Early fall estimates have been obtained at this station and additional work is planned in the future. The Rochelle station is approximately 50 miles downstream of the Treasure Island station. Approximately 5.2 miles of the river immediately upstream of Interstate 80 were sampled in July using two boom equipped e1ectrofishing boats. Fish stocked by Management Crew 55 (Casper) in the river downstream of 1-80 comprise 55% of the total trout estimate above I-80. Upstream migration is significant. Another significant finding is that walleye are the second most abundant game fish in this portion of the river during the summer period. Additional sampling in future years may reveal if the walleye population is expanding. The most significant limiting factor on downstream changes in wild trout populations is probably habitat and the decline in associated tributary streams. As an example, Sage Creek, which enters the North Platte approximately 22 miles upstream of Interstate 80, introduces a tremendous amount of colloidal sediment which in turn, limits spawning and inhibits food production. Water temperatures can also reach limiting levels during low flow periods in late summer. Fishermen use and harvest was evaluated at four locations: Treasure Island, Saratoga, Foote and Pick Bridge. This section will address the changes in fi shermen use and harvest wh i ch have occurred since imp 1 ementat i on of the slot limit regulation. Data from the 1986 creel survey will be compared to the next most recent survey which occurred in 1979. 1) Non-residents accounted for 52% of all visitors. Colorado residents accounted for 77% of those visitors. Total non-resident use is down slightly from 1979 (61%). 2) Non-residents comprised 64% of all license types in 1986. The one day license was the most popular among non-residents. In 1979, non- resident license types comprised 70% of the total. Of particular interest is that of all interviewed visitors (2,689), only 45% (1,215) held fishing licenses. This indicates that a majority of visitors are using the river environment for activities other than fishing. 3) The most significant change in boating use as recorded by time lapse cameras, was a decrease between Bennet Peak and Treasure Island. This difference is most likely attributed to better flows in other river sections and the long shuttle involved with floating the Bennet Peak section. All other areas showed increases in use. Jon boats are the 7