1.
Radio-telemetry was used to monitor the movements of small (<450 mm total
length) resident rainbow trout and recently-stocked rainbow trout in the Clinch
River. Twenty resident trout that had resided in the river at least six
months were collected and implanted with 3.8 g radio tags on 24-25 June
1998. Two groups of rainbow trout being reared at Buffalo Springs State
Fish Hatchery were implanted with radio tags on 8 July 1998 (n = 19) and 16
September 1998 (n = 11).
2. Most of the tagged and stocked rainbow trout died quickly
or emigrated out of the tailrace, and few were harvested by anglers. In
contrast, the resident rainbow trout persisted significantly longer, and more of
those fish were harvested over the study period. Also, recently stocked
rainbow trout were more active and occupied larger reaches of the river than
resident trout.
3. These telemetry results confirmed earlier observations that
rainbow trout stocked into the Clinch River as catchables (as opposed to
fingerlings) suffer high rates of natural mortality and low harvest rates.
Poor survival was probably linked to excessive activity, which is energetically
costly and exposes stocked trout to greater predation risks. Another
factor that could help explain why stocked rainbow trout fared so poorly was
their condition coming out of the hatchery. Although their weights were
similar to that of resident fish of similar lengths, many of the hatchery fish
were missing multiple fins.
4. Radio tags (16 g) were implanted into 15 trophy brown trout
(greater than 450 mm total length) and nine trophy rainbow trout between
December 1997 and May 1998. Post-implantation survival was very low.
Only three rainbow trout survived past 50 days; at least one was harvested and
none survived through the end of the study (November 1998). At least two
of the tagged brown trout were harvested by anglers, and only four brown trout
survived through the end of the study.
5. The four brown trout that survived over the entire study
displayed movement and activity patterns typical of river-dwelling brown
trout. Movements were limited during the winter, spring, and fall months,
but in the fall all fish displayed significant movements associated with
spawning migrations. Three of the fish moved up to and above the weir dam,
where they briefly resided before returning downriver. The fourth
fish dropped downriver about 4 km each fall.
6. The seasonal movements of three tagged brown trout above
the weir dam confirmed earlier observations that many large trout of both
species move upstream each fall, ostensibly to spawn. If conserving and
enhancing stocks of trophy trout were a priority in the Clinch River, management
efforts could focus on reducing the exploitation of large trout each fall in the
upper reaches of the tailwater.
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