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(1977), and Wiley et al. (1977). The back-calculated total lengths of brown trout sampled from 1975 through 1977 are presented in Table 33 (Schmidt et al. 1980b). There has been a general decline in first year reservoir growth rates since 1973. Average first year reservoir growth rate was 4.4 inches for the fish sampled during the project period. This compares to an average first year reservoir growth rate of 8.4 inches as reported by Varley et al. (1971b) through 1971 and a 5 to 6 inch average reported by Wiley et al. (1977). Brown trout were planted at an average size of 3 inches in the spring from 1968 through 1972. From 1972 to 1981 brown trout were planted at an average size of 5 inches in the fall. Table 33 shows that when the switch from spring to fall planted brown trout occurred, average first year reservoir growth rates decreased. For the period 1967 through 1972 average first year reservoir growth was 5.1 inches as compared to 3.6 inches for the period 1973 through 1977. Although brown trout are growing at a slower rate during their first 3 years of life, growth after age IV is quite rapid. Figure 10 shows that brown trout have a more con- sistent rate of growth in all areas of the reservoir than do rainbow trout. Age and growth data concerning species of cutthroat trout were first ana- lyzed by Varley et al. (1971b). Cutthroat trout have never been a significant part of the harvest in Flaming Gorge, even after the large plants of Snake River and Strawberry Reservoir cutthroat trout stocked from 1978 through 1980. Age and growth studies from the returns of these two species of cutthroat trout were not completed because of their disappointing return to the creel. Growth rates of surviving cutthroat trout appear to be at least as good as rainbow trout. Four adipose fin-clipped Snake River cutthroat trout (planted during the fall of 1980 at an average total length of 7.0 inches) had a mean length of 15.0 inches when harvested in 1982. Age and growth analysis of Flaming Gorge lake trout has been difficult because of scale reading problems. No known-aged fish were added to the popula- tion until September of 1979, when 13,500 adipose fin-clipped lake trout were stocked. A search for a method or body structure which might be used to deter- mine age and growth of Flaming Gorge lake trout revealed a fish aging service in Saskatchewan, Canada. Mr. Bill Musker, Fish Aging Supervisor of Saskatchewan, Canada, was hired to section pectoral fin-rays and determine age from lake trout collected during 1979 and 1980. A total of 347 pectoral fins were collected and sent to Mr. Musker in 1981. After sectioning, only 182 of the fin-rays could be read and aged. Table 34 summarizes the aging of pectoral fin-rays from the lake trout sent to Mr. Musker. Mr. Musker concluded that pectoral fin-rays were not good structures to use for aging Flaming Gorge lake trout since there was little or no variation between the hyaline and opaque areas in the fin sections. The reason for this poor definition may be linked to the nearly continuous growth of lake trout in Flaming Gorge throughout the year. If the aging of lake trout found in Table 34 is correct, there is considerable variation in the growth of lake trout in Flaming Gorge. The range in lengths for each age group are con- siderably larger than those reported by McAfee (1966) and Carlander. 0 969). Scales, otoliths and pectoral fin-rays were collected from an additional 30 lake trout in 1981 and sent to Mr. Musker to see if any combination of these structures could be used to verify ages of lake trout. Unfortunately, the samples were lost when a chemical leaked on them. No other samples were sent to Mr. Musker for aging. Y v Ir LE -64-