Tennessee's walleye stocking program was evaluated by releasing fry and fingerlings marked with
oxytetracycline (OTC). Marking efficacy was high (>99%) for walleyes immersed in 500 mg/L
OTC for 6 hours and mortality was negligible. Subsequent recaptures of age-1 walleyes revealed
that little or no natural reproduction occurred in 1999 and 2000 in the five study reservoirs
(Center Hill, Norris, South Holston, Tellico, Watauga). The contribution of stocked walleyes to
those two year classes ranged between 92 and 100%.
Adult walleyes were sampled with experimental gill nets in six reservoirs (the five mentioned
above and Dale Hollow). The oldest walleyes (up to age-21) were in Watauga Reservoir; the
youngest population was in Center Hill Reservoir, where only one fish was older than age-4. The
age-class structure in the six reservoirs indicated that most of the walleye fisheries were
dependent on TWRA's stocking program because natural reproduction was usually low or
inconsistent over the last decade.
Trout stocking rates and threadfin shad catch rates together explained a significant amount of
variation in adult walleye robustness. The heaviest walleyes were in South Holston, Dale Hollow
and Watauga Reservoirs. Significant between-year variation was also detected for four of the six
populations sampled.
No threadfin shad were collected in Watauga Reservoir, but they were caught in similar numbers
in the other five reservoirs. Alewives were in all six reservoirs and their catch rates varied
significantly; mean catch rates were higher in Watauga and Dale Hollow (207-300/net night) than
in the other four reservoirs (7-23/net night).
Walleyes grew rapidly in all reservoirs; the average time to reach 406-mm total length ranged
from 1.7 to 2.1 years.
Fishery yields under different minimum size limits were simulated using the Beverton-Holt
equilibrium yield model. Three size limits (381-, 406-, and 457-mm total length) increased yield
in all reservoir compared to no size limit at most levels of exploitation when conditional natural
mortality rates were low (less than 20%). At higher natural mortality rates, the benefits of a minimum
size limit were eliminated. The observed longevity of walleyes (maximum age averaged 13 years
over all reservoirs) indicated that natural mortality rates were low; thus, minimum size limits were
appropriate management actions in all reservoirs. Although yield was usually highest under
simulated 457-mm length limit, the benefits were slight unless conditional fishing mortality rates
were high (>40%) and natural mortality rates were low (10%).
Only one walleye population (Center Hill) exhibited characteristics of heavy exploitation.
Although most populations were sustained through a stocking program, the abundance and size
structure of most populations was excellent. Large variations among reservoirs in walleye
robustness and forage abundance suggested that stocking rates should be matched to the supply
of available forage. |