Parr and smolt yield, migration timing, and age structure in a wild steelhead population, Fish Creek, Idaho Alan Byrne Idaho Department of Fish and Game 600 South Walnut Street Boise, Idaho 83707 Adult enumeration May 11, 1997 Adult handling procedures Spawners Record sex, fork length, origin, hook scars and other marks Scan for PIT-tag Obtain scales for aging Obtain tissue sample for genetics Punch right operculum, release upstream Kelts Same as spawners (except no scales or tissue if right operculum was punched) Punch left operculum of live kelts and release downstream of weir Adult escapement 1. The number of spawners passed upstream plus the number of unmarked kelts recovered. 2. An ML estimate using the number of kelts captured, number of marked spawners passed upstream, and number of marked kelts recovered. 3. If weir breached and kelts were not captured use the proportion of run on the date weir was breached to expand number of spawners. Fish Creek wild steelhead escapement Arrival of spawners and kelts at weir Age structure of adults by Spawn year Length frequency of spawners (all years) Mean length of spawners and kelts all years combined KeltsKelts Recovered RecoveredKeltsKelts Recovered Recovered Juvenile enumeration Screw trap procedures Count all steelhead trapped PIT-tag all fish after checking for re-captures. Record the fork length and weight. Release < 50 tagged juveniles upstream each day for a trap efficiency estimate. Collect scales from all size classes for aging. Record weather, river level, conductivity, water temperature, and trap RPM each day. Migrant and smolt estimates Number of juvenile out-migrants estimated with mark-recapture methods by stratifying periods based on flow. Use Cormack/Jolly-Seber (PitPro) to estimate the number of smolts using detection data from Snake River and McNary dams. Age structure estimated with Rmix. Use age proportions to parse total juvenile migrants and smolt estimates to spawn year. All years combined Yearestimate Fallestimate Fall migrants per female spawner Smolts per female spawner Actual data Logtransform 74 river km Age structure of fall migrants Lochsa River drainage