Matt A. Kulp and Stephen E. Moore, Great Smoky Mountains
National Park, 107 Park Headquarters Road, Gatlinburg, Tennessee 37738
Keywords: trout removal
We evaluated multiple electrofishing removals of rainbow trout Oncorhynchus
mykiss in one year as a management tool for the restoration of native brook trout Salvelinus
fontinalis in a small southern Appalachian stream. Six, three-pass depletion removal
efforts were conducted between June 1996 and October 1997 using backpack electrofishing
gear. After removal 4 (October 1996), 105 native southern Appalachian brook trout of
various age-classes were reintroduced into Mannis Branch. No rainbow trout were collected
during removal 6, indicating five removals were required to successfully eliminate rainbow
trout from Mannis Branch. During the study, 428 rainbow trout were removed from the
treatment area. The initial removal collected 296 rainbow trout (70% of total), of which
62 were YOY (21%) and 234 were age-1 (79%) or older. Removals two through five were
dominated by YOY rainbow trout (57-83%). The initial two removals successfully eliminated
96% of the reproductively mature adults as well as 86% of the YOY. Surveys conducted in
May 1997 indicated adult brook trout successfully spawned initiating re-population of the
treatment area. Initial population estimates were compared to the actual catch to assess
the accuracy of population estimators. Population estimates from removal one
underestimated the actual population size by 30%. It was not until after removal three
that the actual number of rainbow trout fell within the population estimate 95% confidence
interval for the treatment area. Multiple removals exhibited no negative population level
effects on rainbow trout or blacknose dace Rhynichthys atratulus in Mannis Branch
or a control stream, despite being exposed to six, three-pass depletion electrofishing
efforts. Based upon these results, a minimum of two removals conducted per summer should
eliminate rainbow trout reproduction and significantly reduce the number of years required
to successfully restore a small southern Appalachian stream.