Acoustic Tracking of Redband Trout Oncorhynchus mykiss var. gardneri in Lake Roosevelt, Washington

Little is known about the movements of native Columbia River Redband trout (Oncorhynchus mykiss var. gardneri) in Lake Roosevelt, a reservoir formed by Grand Coulee Dam on the Columbia River. Since April 2013, acoustic telemetry was used to identify long-term horizontal movements of redband trout within this reservoir. This study tagged 50 fish (TL 408 ±148 mm) from April - May 2013 and 60 fish (457 ±56 mm) from March - May 2014 in tributaries of Lake Roosevelt. The goal of this study was to determine if redband trout from different tributaries occupy unique distributions within the reservoir. The movements were modeled using state-space modeling (Dynamic Brownian Bridge Movement Model) in R. Fish were grouped by capture stream and their movements were compared spatially. The distribution of fish from tributaries close together were similar (Spearman’s correlation = 0.2167) while the distributions from distant tributaries were unique (Spearman’s correlation = -0.005). These movements are in agreement with work completed by a concurrent study that identified genetic stock structure. Genetically similar groups had similar movements and vice versa. The methods used to model movements of fish to determine their unique distribution could aid in the management of native fish.