Trout Population and Production Dynamics in North Carolina State Park Streams

Abstract

ABSTRACT

WALLACE, BENJAMIN CRAIG. Trout Population and Production Dynamics in North Carolina State Park Streams. (Under the direction of Thomas J. Kwak.)

Stream trout (Salmonidae) fisheries provide popular recreational fishing opportunities in North Carolina and nationwide. These fisheries may be managed under historical practices with limited information available to evaluate or plan management alternatives. The use of dynamic rates of population functions can serve as a superior method to quantify trout populations and provide a scientific basis from which to guide management decisions. Three trout species, brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss, inhabit streams under a variety of management regulations and stocking regimes in Stone Mountain State Park, North Carolina. To investigate trout population and production dynamics in intensively utilized southern Appalachian Mountain streams, we studied six stream reaches to (1) intensively sample and quantify critical population parameters of stream trout in a State Park, (2) develop empirical estimates of stream trout production rate based on population parameters, (3) sample and quantify nongame fish assemblages associated with trout fisheries, (4) measure and quantify water quality and instream habitat characteristics associated with trout and nongame fish assemblages, and (5) present the results of this study in an applied context toward guiding management strategies for stream trout fisheries in North Carolina State Parks, as well as other coldwater streams across North America. Of the three unstocked streams sampled, brook trout were present in two and brown trout were present in all three. Wild trout are short-lived with a maximum age of two years among fish sampled in Stone Mountain State Park streams. Mean annual brook trout density in unstocked waters ranged from 195.09 to 234.13 fish/ha and that for brown trout was 169.87 to 2,038.69 fish/ha. Annual brook trout production ranged from 5.91 to 8.81 kg/ha and annual brown trout production ranged from 14.07 to 64.16 kg/ha in unstocked waters. Age-0 and age-1 fish contributed the most production in the unstocked waters. Allopatric brook trout were found in the uppermost headwaters of two unstocked streams. Brook trout, brown trout, and rainbow trout were present in all three sampled reaches of the East Prong Roaring River. Trout densities in delayed harvest managed waters fluctuated widely over time and could not be explained by the frequency and density of stocking alone. Few trout remained in the sampling reaches for long periods of time after stocking into delayed harvest waters. Trout density in hatchery supported waters declined rapidly after being opened to harvest. Nongame fish were collected in four of the six sampling reaches, and species richness ranged from 2 to 13. Nongame fish density was highest in a portion of the East Prong Roaring River where instream and riparian habitat rehabilitation previously occurred. Instream habitat, stream gradient, and overhead cover were similar within unstocked waters and within stocked waters but were different between the two stream groups. Stream temperatures in the East Prong Roaring River are marginally suitable for trout. Other water quality measurements were similar among all reaches that were studied. Salmonid production can be used to monitor success of stream trout populations and, in conjunction with the ecotrophic coefficient, guide management decisions in coldwater streams nationwide. P/B ratios developed from our empirical estimates of production can be used to estimate production in the future with reduced sampling effort. Based on our findings, management options for streams in Stone Mountain State Park are presented. My results, in addition to future research and monitoring, can improve understanding of trout population dynamics, native trout distribution, habitat modifications, and management effects.