The San Juan River in Utah is home to endangered Colorado pikeminnow (Ptychocheilus lucius) and razorback sucker (Xyrauchen texanus). In 2020–2021, FISHBIO was hired by the San Juan River Basin Recovery and Implementation Program to develop trapping options as part of recovery efforts for these sensitive species. The Program has been investigating methods to help Colorado pikeminnow and razorback sucker pass upstream from Lake Powell in southern Utah to potentially critical spawning habitat in the San Juan River. Currently, these species are unable to access these spawning reaches because their migratory pathway has been blocked by a waterfall formed by alternating reservoir water levels and shifting of the river channel. Although the waterfall prevents movement of these sensitive species, it also prevents nonnative piscivorous sport fishes from invading important spawning and juvenile rearing habitat. As a consequence, the Program has been capturing fish downstream of the waterfall and selectively transporting target species upstream.
To improve capture efficiency of native fish species, FISHBIO staff performed an on-site evaluation to better understand the specific requirements and constraints associated with the environmental challenges of trapping and transferring fish in this extremely remote location. Leveraging our experience with weirs and fish traps in California and abroad, FISHBIO devised a series of tailored solutions for minimally invasive trapping and provided a feasibility assessment of each method to the Program’s Biology Committee. We then fabricated and field-tested customized trapping solutions. For one solution, we constructed rigid weir panels (2.5 ft tall by 10 ft long) that can be set up in different configurations to concentrate and trap fish within an area that can be easily seined. We built a custom fyke “gate” that provides a narrow opening for fish to enter and can be closed when seining the area to prevent fish from escaping.
The second solution was an aluminum box fyke trap (4 ft tall by 4 ft wide, by 8 ft long) with a shallow bevel on the bottom opening to accommodate fish that swim along the riverbed. The top and portions of the sides can be removed to access fish captured inside. Owing to the size and weight of the metal box trap, we also built a custom pontoon raft with a pully system to raise and lower the trap and aid in transporting and positioning the device in the river. Deflated airbags were affixed to the underside of the trap. In the event that silt and sand build up inside, these can be inflated using pressurized air tanks (strapped to the pontoon raft) to aid in retrieving the trap from the water. Our staff delivered the equipment to the remote project site and led its initial deployment, which included training on how to set up and use the equipment.
