Cooperative Fish and Wildlife Research Units Program: Hawaii
Education, Research and Technical Assistance for Managing Our Natural Resources

Species conservation requires a clear understanding of the availability of suitable habitat and the subsequent use of those habitats. In cases where species declines have occurred and gone undetected to conservation managers, habitat alteration, fragmentation and loss are often the largest contributors. River fragmentation often results in altered flow regimes, which is considered the primary variable determining riverine habitat availability. Blue Suckers Cycleptus elongatus are associated with riffle and run habitat, a habitat type that is especially impacted when river flows are altered. The objective of this research was to identify the extent of suitable habitat and mobility for Blue Sucker in the Colorado River, Texas. To understand habitat selection and use, Blue Suckers (N = 49) were surgically implanted with combined acoustic radio transmitter tags. During 2015-2017, thirty-eight attempts were completed to relocate individuals using mobile tracking. Optimized hotspot analysis identified three river reaches critical for Blue Sucker that accounted for 20% of the study area. Blue Sucker used these locations year-round including during spawning. Habitats used by Blue Sucker were composed of gravel, cobble, boulder, and bedrock typically in riffle and run habitat. Additionally, mobility, as measured by home range size, increased as riffle density decreased. The larger home ranges were presumably to find suitable habitat to complete aspects of their life history. The results of this study suggest that suitable habitats are limited throughout the fragmented riverscape. Conservation action in the form of habitat construction or increased stream connectivity through barrier mitigation could have positive impacts on the future of Blue Sucker in the lower Colorado River, Texas.