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AGE AND GROWTH BACKGROUND a Age and growth studies on rainbow trout have been conducted since the first rainbow were planted in the reservoir in 1963. Brown trout growth rates have been studied since 1967. Numerous papers and annual reports have been written describing these studies (Varley, Regenthal, and Wiley 1971a; Schmidt et al. 1980b). Analysis of rainbow age and growth during the first 4 years of the pro- ject period showed very little change in growth rates from earlier studies. However, analysis of the brown trout growth data showed that fall planted fish grew slower in their first year in the reservoir than spring planted fish. Lake trout have exhibited superior growth in Flaming Gorge. However, aging lake trout scales has proven difficult. Known-aged fish were first added to the population in 1979 and again in 1983 to study the growth of this species in Flaming Gorge. Smallmouth bass grow slowly in the reservoir and the small size of fish har- vested has significantly affected angler interest in this species. The size of Flaming Gorge kokanee shows that kokanee salmon have the potential to become an important sport fish as well as an important forage species. The future contri- bution of smallmouth bass and kokanee to the fishery cannot be overlooked. Therefore, age and growth studies on these species were included in the project. METHODS Lengths, weights, and scale samples were collected randomly from important sport fish during creel surveys through 1979. Age and growth data were also collected from selected sport fish species while gill netting, purse seining and electrofishing. Impressions of the scales were made on plastic cards and exam- ined with a micro-projector to age each fish and determine the distance to each annulus to assess increments of growth. Utah's standard "Big Fin" computer program was used to determine mean back-calculated lengths at each annulus for each year class. The length-weight relationship, mean condition factor and sample size were also calculated by the program. Age and growth data were also a part of the general life history studies conducted on lake trout, kokanee salmon and smallmouth bass. Lake trout scales, pectoral fin-rays and a few otoliths were taken during creel surveys and gill net sampling in 1979 and 1980. The pectoral fin-rays were dried and placed in individual envelopes. The rays were then sent to Mr. Bill Musker, Fish Aging Supervisor of Saskatchewan, Canada, for sectioning, marking, and aging. Mounted fin-ray sections and a detailed report concerning the aging was received from Mr. Musker during 1981. Pectoral rays, otoliths and scales were then taken from 30 more lake trout and sent to Mr. Musker. Unfortunately, the samples were ruined in an accident in his laboratory. Additional age and growth data on smallmouth bass were collected during night electrofishing. Kokanee salmon data were collected from fish sampled with the purse seine. Length-frequency histograms were drawn to express the age and growth data of kokanee salmon. -55-