Comparing Sampling Techniques for Juvenile Burbot in Riverine Systems: An Occupancy Modeling Approach

Burbot Lota lota in the Kootenai River of Idaho have declined in abundance over the past 60 years. Consequently, conservation efforts (e.g., habitat restoration, conservation aquaculture) have been initiated by a multiagency coalition. Despite increased monitoring efforts, few juvenile burbot have been sampled in the system. Our research compares three sampling techniques (i.e., boat-mounted electrofishing, benthic trawls, small-mesh hoop nets) for sampling burbot with a particular focus on juveniles. Due to low burbot densities in the Kootenai River, the Green River of Wyoming was selected as a secondary sampling location and used to compare sampling techniques in a system with higher burbot densities. In the summer (May-August) and fall (September-October) 2012, 26 reaches were surveyed two to six times in the Kootenai and Green rivers. Multi-scale, multi-method occupancy models were used to compare sampling techniques in the summer and fall seasons. Hoop nets had the highest detection rate among sampling techniques. Detection rates varied by river system and appear to be influenced by depth and temperature. Results of this research will help identify the best sampling technique(s) for juvenile burbot in large river systems.