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( (;) o <-:> (...) (.0 en San Juan Seven Year Research plan WORK STATEMENT/PROTOCOL ADULT MONITORING'- RECLAMATION (Durango Project Office) Background: Colorado squawfish and razorback suckers have both been collected from the lower San Juan River and the San Juan arm of Lake Powell (Platania, 1990). More specifically, one adult Colorado squawfish, collected from this arm of the lake in April 1987, was subsequently recaptured from the San Juan River in September of that yeal:. This squawfish was the only one that was l:ecaptured during a three year study period. This single recapture demonstrated that squawfish utilized habitat in both Lake Powell and the San Juan River. However, the duration and possible seasonal utilization of these habitats remain largely unknown. Since 1987, the elevation of Lake Powell has steadily declined from 3698 feet to the current elevation of 3628 feet. During this period, extensive silt deposits have been exposed within the upper several miles of the San Juan arm of Lake Powell. These deposits have served to re-alter the original river channel resulting in the creation of a large vertical drop in the pi ute Farms area. significantly, this estimated 20 foot drop appears to be an impediment to the upstream movement of reservoil: fish. Fish species that seasonally use the San Juan River would be expected to congregate at the base of this blockage, possibly including Colorado squawfish. Objectives/Tasks: Objectives and tasks for this effort would be essentially the same as those listed under the Adult Monitoring work statement for the USFWS. ( General Methods: The area of study would be confined to the extreme upper end of Lake Powell extending upstl:eam in the San Juan River to Slickhorn Rapid. Principally, the focus of the field effort would be to collect adult Colorado squawfish for the implantation of radio transmitters; however, all rare or endangered fish species would be appropriately processed per existing protocols. Field data collections would begin in May, 1992. Fisheries Collections All electrofishing will be accomplished using a motorized 17 foot Jon Boat equipped with a Coffelt Model Variable Voltage Pulsator (VVP 15). The cathode will consist of fOUl: to six steel electrodes per boom depending on existing water conductivity. Pulsed direct current will be used exclusively. Electrofishing would be conducted during both the day and nighttime periods and on both sides of the river banks. Principally, the river seccion between the "wa.terfall" and the reservoir would be sampled using electrofishing exclusively, although some deeper water habitats would also be sampled with entanglement nets. The reservoir would be sampled using both gill and trammel nets. The length of nets will also vary, according to available nettable habitat, from 100 to 300 feet and the mesh size will vary from two to three inches. Since it may not be possible to launch the electrofishing boat upstream of ths "waterfall", the river upstream of this point would be sampled utilizing seines and entanglement nets. All fish captured will be identified and measul:ed (TL). In addition, all rare or endangered fish will be weighed and will be PIT tagged. Adult Colorado squawfish Over 500 mm in length (TL) will be surgically implanted with a radio transmitter using standardized methods. All of these implanted fish will be transported at least five miles upstream of the "waterfall" and released. The movements of these fish will be monitored daily for the duration of the sampling period. L A7