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~ ~ ATTACHMENT TASK DESCRIPTIONS FY92 WESTWATER CANYON TASK 1: DETERMINE SPAWNING AND NURSERY REQUIREMENTS Subtask lA: Radio-implant. Fish, The principal tool used to det.ermine the spawning requirement.s of humpback chub in Westwater Canyon will be radiotelemetry. Twent.y wild adults will be captured by elect.rofishing or t.rammel nets and radiotagged in March wit.hin the l3-km reach of river recognized as t.he primary habit.at for t.he fish. These 20 fish will be capt.ured, t.agged and released in two lots of 10 fish each within t.wo strata; one above t.he main rapids (RM 120-124), and one in the main rapids section (RM 116-120). The purpose for this stratification is t.o determine if spawning habitat is dist.ribut.ed t.hroughout Westwater Canyon or if it is limited to one or few specific areas. RadiotranslDitt.ers wit.h external ant.ennas will be used to maximize signal reception from the relatively deep channel ; average maximum depths may range from 5 to 13 m. Subtask lB: Radiot.rsck Fish. Following radioimplant in March, the fish will be located through 2-day surveillances, one in mid-April and one in early May. Tracking will be conducted from motorized rafts using Smith-Root SR-40 and RF-40 receivers, as well as ATS receivers. The trip in early May will incorporate random sampling to assess spawning condition. Degree of tuberculation, coloration, and expression of gametes will be used as criteria t.o judge their closeness to spawning. Males will be judged closest to spawning by the condition of their milt; the milt start.s clearish, then becomes whit.e, and is t.hick and completely white when closest. to spawning. The females will be judged closest to spawning when the abdominal area extends, droops and softens in the pre- genital area. The genital papillae enlargens and a feathery sheath develops covering the genital opening (Personal communication with Buddy Jensen, October 24, 1988). These conditions first appear 1 to 2 weeks prior to actual spawning. This determination will be made in a 2-day sampling period, which, may be necessary to repeat until the proper spawning criteria are met. Although river flow and temperature will be monitored throughout the runoff period, past investigations have failed to relate spawning to these parameters (Yaldez and Clemmer 1982, Archer et al. 1985) Once the fish are judged t.o be within a week of spawning, two crews will be activated to monitor t.he radio tagged fish. These crews will spend 14 days monitoring movement of the fish during the spawning period. Tracking will be done from Achilles sportboats equipped with 40-hp Yamaha outboards. Much of the tracking can and will be done afoot by following the canyon rim above t.he river. An effort will be made to contact and monitor all 20 fish during this l4-day period, with each crew spending at least one day with each fish. Nighttime monitoring will be conducted where crews can reasonably establish a base camp near the fish. Movements and habitats used by the radiotagged fish during this 14-day monitoring period will be recorded and mapped; this is in addition to the mapping that will be done on specific spawning sites. In addition t.o tracking, random sampling of adults will continue in order to periodically check on the progress of gonadal development and spawning. This sampling will be done discretely in order to minimize the impact on the population; the numbers of fish captured and examined will be kept minimal.