Spatial and Temporal Consumption Dynamics of Trout in Catch‐and‐Release Areas in Arkansas Tailwaters

Abstract

Restrictive angling regulations in tailwater trout fisheries may be unsuccessful if food availability limits energy for fish to grow. We examined spatial and temporal variation in energy intake and growth in populations of Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss within three catch-and-release (C-R) areas in Arkansas tailwaters to evaluate food availability compared with consumption. Based on bioenergetic simulations, Rainbow Trout fed at submaintenance levels in both size-classes (≤400 mm TL, >400 mm TL) throughout most seasons. A particular bottleneck in food availability occurred in the winter for Rainbow Trout when the daily ration was substantially below the minimum required for maintenance, despite reduced metabolic costs associated with lower water temperatures. Rainbow Trout growth rates followed a similar pattern to consumption with negative growth rates during the winter periods. All three size-classes (<250 mm TL, 250-400 mm TL, >400 mm TL) of Brown Trout experienced high growth rates and limited temporal bottlenecks in food availability. We observed higher mean densities for Rainbow Trout (47-342 fish/ha) than for Brown Trout (3-84 fish/ha) in all C-R areas. Lower densities of Brown Trout coupled with an ontogenetic shift towards piscivory may have allowed for higher growth rates and sufficient consumption rates to meet energetic demands. Brown Trout at current densities were more effective in maintaining adequate growth rates and larger sizes in C-R areas than were Rainbow Trout. Bioenergetic simulations suggest that reducing stocking levels of Rainbow Trout in the tailwaters may be necessary in order to achieve increased catch rates of larger trout in the C-R areas.

Trout Responses to Stocking Rates and River Discharge within a Southeastern U.S. Hydropeaking Tailwater

“…The temporal and spatial patterns in mean length and relative abundance of Rainbow Trout and Brown Trout could be used to direct management strategies for each species. Multiple constraints on successful recruitment of stocked fish exist and managers of put‐grow‐take trout fisheries may consider the role of density dependence and food availability in limiting survival and growth of stocked populations (O'Rouke 2014; Flinders and Magoulick 2017). Implementing incremental changes in the number of Rainbow Trout stocked did not result in readily apparent changes in relative abundance or mean length in this study.…”

“…For instance, tailwater salmonid fisheries are prevalent in the Southeast, where main‐stem river impoundments are in place to meet flood‐control and regional electric power demand (Baker and Sammons 2021). In Arkansas, tailwater salmonid fisheries are maintained through extensive stocking, natural reproduction, and regulations (e.g., harvest regulations and special regulation areas; Flinders and Magoulick 2017; AGFC 2021). For example, the White River system in Arkansas has three main‐stem impoundments and two impoundments in tributaries that support the largest salmonid fisheries in the state (Pender and Kwak 2002).…”