Blue Sucker Life History Project
In 2004 BIO-WEST began conducting an instream flow study to develop hydraulic modeling tools and habitat use criteria for fish in the lower Colorado River to assess potential changes in habitat availability under various water-release strategies, using blue sucker (Cycleptus elongatus) as a model. Our field crews sampled all blue sucker life stages, using radio telemetry to track fish. They successfully tagged and tracked 30 adults by boat and plane, and extensively sampled for larval and juvenile blue sucker, for which little habitat information is known. Aside from fish sampling, our data collection included placement of benchmarks, surveying, collection of river bathymetry and discharge, and collection of depth and velocity validation points. As a result of these studies, we have added substantial information to the blue sucker behavioral knowledge base including adult habitat use, spawning habitat use, and migratory behavior.
“This fish is a sensitive species,” said BIO-WEST Principal and Project Manager Ed Oborny. “It needs certain types of habitat and certain levels of water quality to survive and to be able to move up and down the Colorado River. The adult population tends to be relatively strong. A sensitive species like this one is a good indicator of the health of the river.” Data have shown that blue sucker require at least some deep, high-velocity rapids throughout the year in order to maintain a successful population. Perhaps even more important is the maintenance of adequate amounts of spawning habitat during early spring months. Over the course of the study, the project team identified seven different spawning areas either by witnessing spawning activity or by collection of blue sucker eggs.
Radio-telemetry data indicate that spawning migration of blue suckers in the lower Colorado River is strongly tied to discharge, and is likely initiated by high flows. During years of lower flow, blue sucker tend to stay close to their “home” riffle and spawn with members of their same riffle sub-population. Therefore, high-flow years may serve as important dispersal mechanisms needed to stimulate gene flow between distant sub-populations from various riffle complexes.
This project is a component of the Lower Colorado River Instream Flow Study.
