Minthorn Springs Creek Summer Juvenile Release and Adult Collection Facility; Operation, Maintenance and Evaluation; 1991 Annual Report.

Abstract

The Confederated Tribes of the Umatilla Indian Reservation (CTUIR) and Oregon Department of Fish and Wildlife (ODFW) are cooperating in a joint effort to supplement steelhead and re-establish salmon runs in the Umatilla River Basin. As part of this program, Bonifer and Minthorn Acclimation Facilities are operated for holding and spawning adult steelhead and fall chinook salmon and acclimation and release of juvenile salmon and steelhead. Regularly-scheduled maintenance of pumps, equipment and facilities was performed in 1991. Major repairs to one Minthorn pump were required and flood damage at Minthorn necessitated the replacement of rock and gravel around the pump house and steelhead brood holding area. Several modifications to the steelhead brood holding pond were also made to help reduce mortality. These changes appeared to be successful as evidenced by the reduced number of mortalities. Total prespawn mortality in 1990-91 was 10.4%. This compares to 20.0 to 39.0% for the previous three years at Minthorn. A total of 202 adult steelhead were collected for broodstock at Threemile Dam from November, 1990 through April, 1991 and held at Minthorn. Utilizing a 3 x 3 spawning matrix, a total of 410,356 eggs were taken from 64 females. The eggs were transferred to Irrigon Hatchery for incubation and initial rearing. The fish were then transferred to Umatilla Hatchery for further rearing and later release into the Umatilla River. A total of 347 fall chinook salmon were also collected for broodstock at Threemile Dam and held at Minthorn. Using a 1:l spawning ratio, a total of 601,548 eggs were taken from 159 females. They were transferred to Umatilla Hatchery for incubation, rearing and later release into the Umatilla River. Acclimation of 100,505 spring chinook salmon and 42,610 summer steelhead was completed at Bonifer in the spring of 1991. At Minthorn, 152,974 coho and 79,672 fall chinook salmon were acclimated and released. In the fall, 81,144 spring chinook salmon were held at Bonifer for a three-day post-transport recovery period. Control groups of spring and fall chinook salmon and summer steelhead were released instream concurrent with the acclimated releases to evaluate the effects of acclimation on adult returns to the Umatilla River. Test and control groups were tagged by ODFW for acclimation studies to be performed at the Bonifer and Minthorn facilities in 1991 and 1992. Each group received three separate coded-wire tag codes. One experiment for fall chinook salmon and two experiments for spring chinook salmon were tagged. The progress of outmigration for acclimated releases was monitored at the Westland Canal fish trapping facility by CTUIR and ODFW personnel. Because of high spring flows in the Umatilla River however, the trap was not opened until mid-June and few fish were trapped, suggesting most had already migrated downriver. Personnel from the ODFW Eastern Oregon Fish Pathology Laboratory in La Grande took samples of tissues and reproductive fluids from Umatilla River summer steelhead and fall chinook salmon broodstock for monitoring and evaluation purposes.