1. Between March 1997 and March 1998, the trout fishery in the South Fork of the Holston River below Holston Dam was sampled to describe rates of growth, survival, natural reproduction, and harvest of stocked and wild rainbow trout and brown trout. Over 40,000 hatchery trout were tagged with wire microtags and 127 electrofishing samples were collected. A creel survey was conducted between March and October 1997 in conjunction with the Tennessee Valley Authority, and habitat in the tailwater was mapped using GPS receivers and GIS software. The number and biomass of trout overwintering each year was also estimated.

2. Trout habitat in the 22 km (14 miles) below Holston Dam was excellent and much better than the habitat in most other Tennessee tailwaters. Riffle complexes in the tailwater accounted for the most area (0.40 km 2), followed by pools (0.34 km 2 ) and run complexes (0.24 km 2 ). The riffle:run:pool ratio was 2:2:1. Overhanging stream cover along the banks was present in all habitat types; large woody debris was not abundant except in pools. Water temperatures typically varied by as much as 70C between periods of generation, but were usually below 20 0C. Temperatures never exceeded 22 0C and dissolved oxygen concentrations below the aerating labyrinth weir remained suitable for good trout growth and survival.

3. During the eight-month creel survey, over 2,100 anglers were interviewed by the TVA clerk. Thirty percent of the anglers interviewed were out-of-state residents; most (94%) Tennessee residents interviewed were from the three counties adjacent to the river. Fishing effort between March and October 1997 totaled about 110,000 hours and represented over 29,000 trips. On a per-area basis, fishing pressure on the South Fork of the Holston River (36 hours/hectare/week)was much higher than the pressure reported for the Elk, Caney Fork, and Clinch rivers in Tennessee (10 - 21 hours/hectare/week). Anglers reported harvesting 1.3 fish per trip and catching 4.7 fish per trip in the South Fork of the Holston River.

4. Return rates for tagged rainbow trout which were stocked following normal stocking procedures were high (40-70%). Tagged rainbow trout stocked exclusively in the lower reach of the river where fishing pressure was less were harvested at a much lower rate (17%), confirming that fishing pressure and harvest regulated the survival of stocked rainbow trout. Harvest rates for tagged brown trout were low (24%).

5. Long-term (200-day) survival of tagged rainbow trout was low (3 - 4%) for those fish stocked in areas of high fishing pressure. Long-term survival of rainbow trout stocked in the lower reach of the river was much higher (24%), as was the survival of the tagged brown trout (56% over 200 days).

6. Mean growth of rainbow trout ranged from 9 to 16 mm and 18 to 34 g per month. Rainbow trout stocked in March grew slower than trout stocked in September 1997; however, this comparison was confounded by the fact that the September cohort was the only Fish Lake strain of rainbow trout stocked into the tailwater in 1997. Pooled growth rates compared favorably with other tailwater trout populations in the U.S.

7. Hatchery and wild brown trout grew at similar rates in 1997 (11 mm and 18 g per month), which was notable because wild fish usually grow faster than hatchery fish. Brown trout grew slower than rainbow trout, which is typical, and their growth in the South Fork of the Holston River compared favorably with populations of brown trout in other tailwaters.

8. Hatchery rainbow trout and brown trout did not exhibit the typical pattern of weight loss after stocking. Although the condition of wild brown trout declined significantly in late summer, the decline was temporary and not problematic.

9. The number of overwintering trout greater than 160 mm total length in the upper 16 km of the tailwater was 58,212 in May 1997 (= 232 kg/hectare); over 80% were brown trout. In March 1998, the number of overwintering trout in the entire tailwater (22 km) was 50,083 (= 170 kg/hectare); again, most of those fish were brown trout. The number and biomass of trout overwintering in the South Fork of the Holston River was much higher than in other Tennessee rivers studied in the 1990s. The change-in-ratio population estimation procedure was precise, cost-effective, and provided the first information ever on trout standing crops in that river.

10. The river was surveyed in December 1997 and 228 trout spawning redds were located; a follow-up survey in January 1998 observed 165 redds. Redd construction was concentrated in six areas distributed over the length of the tailwater. With few exceptions, spawning sites were associated with instream structure such as the weir dam, islands, and bridges.

11. Successful recruitment of wild rainbow trout and brown trout was observed in late summer and fall electrofishing samples. The contribution of wild age-1 brown trout was extremely high in a May 1997 mark-recapture experiment (55% of all overwintering trout); the contribution of wild age-1 brown trout was lower but still substantial in March 1998 samples. The relative contribution of wild rainbow trout to the trout community could not be estimated.

12. The rainbow trout fishery was essentially a put-and-take fishery, as harvest rates were high and few rainbow trout reached trophy size. The trout community was dominated by brown trout, which represented about 80% of the biomass of trout overwintering. Low harvest rates, good survival, and the large sizes obtained by brown trout all contributed to the reputation of the South Fork of the Holston as Tennessee's premier tailwater trout fishery.

13. The South Fork of the Holston tailwater trout fishery is unique in Tennessee in terms of the abundance of quality habitat, the contribution of wild fish, high overwinter trout survival, and excellent size structure of the trout populations. As such, management activities aimed at conserving this valuable resource are warranted, particularly given the high fishing pressure the system receives. Specific management activities or regulation changes cannot be discussed until decisions are made regarding the goals for that fishery. For instance, it is not clear whether the fishery is going to be managed for maximum fishing pressure, high catch or harvest rates, wild trout, trophy fish, or to meet other management objectives. Many management options are available for the South Fork of the Holston fishery, which is not the case at several other large Tennessee tailwater trout fisheries.