•3 Two hatchery smolts moved upstream Acoustic Monitoring of from the release site into the . They held there for >30 days and then moved up the

Mokelumne River •4 Oncorhynchus mykiss PRELIMINARY RESULTS James R. Smith1 , Michelle L. Workman1, 2 3 • All hatchery smolts were detected at least once by the receiver grid. Time from release to last detection ranged from 1 to 114 Joseph E. Merz , Walter Heady , and days 1 • All hatchery reconditioned kelts were detected. Time ranged from 1 to 81 days. Joseph J. Miyamoto • Forty-Seven of sixty-four (73%) of wild O. mykiss were detected by combined stationary and mobile tracking techniques. • Time from release to last detection ranged from 1-136 days for stationary receivers and from 5 to 173 days for 1 East Bay Municipal Utility District, 1 Winemasters Way, Lodi, CA 95240 mobile tracking. 2 Cramer Fish Sciences, 636 Hedburg Way #22, Oakdale, CA 95361 3 University of , Santa Cruz, Long Marine Lab, 100 Shaffer Rd., Santa Cruz, CA 95060 70% 60% Project funded by the California Urban Water Agencies 50% 40% 30% 20% 10% 0% Percent of Release Group Vicinity of Mokelumne Sacramento Delta/Bay None INTRODUCTION Release River River The Mokelumne River Fish Hatchery (Hatchery) has released over 2 million smolt Detections through 7/13/2007 steelhead, Oncorhyncus mykiss, in the lower Mokelumne River since 1995, however, fewer than 750 adults have returned to the Hatchery since 1996. There have been limited data Hatchery Smolts n=57 Reconditioned Kelts n=7 Wild Caught Various n=64 Detections occurred in four major categories: 1)detections in vicinity of release site; collected on the movements of these fish once released. In addition, there is no information 2)detections within the lower Mokelumne River; 3) detections in the Sacramento River and on the timing or movement of naturally spawned O. mykiss in the lower Mokelumne River, 4)detections in the Delta and Bays. or the proportion of that population that exhibits anadromy. We used acoustic telemetry to evaluate movement of hatchery produced and naturally spawned O. mykiss. METHODS •2 We deployed ten acoustic receivers (Vemco VR2W – 69kHz) in the lower Mokelumne River and Delta to compliment the 170 receivers deployed by others throughout the Sacramento- System, Delta and Bays. One hatchery smolt stayed at the release site for 2 days, moved into the Cosumnes River Mokelumne River hatchery and wild O. mykiss were surgically and held there for 47 days, then moved down to and back up the implanted with 123 Vemco V9 transmitters and five V13 transmitters. 57 hatchery smolts released in the Delta A group of 57 hatchery produced O. mykiss smolts ranging in size Sacramento River in < 35 hours. from 168 mm to 231 mm were acoustically tagged and released in the Delta along with a hatchery release group of 356,900. Naturally

produced adult, smolt and silvery parr O. mykiss (64) ranging in size 64 naturally produced and 7 reconditioned kelts from 163 mm to 591 mm were released at capture site and seven released in the Mokelumne River hatchery reconditioned kelts ranging in size from 465 mm to 610 mm were released adjacent to the Mokelumne River Hatchery. •4

•5 •6 Mobile tracking was conducted by boat on the Mokelumne River •3 from to above Hwy 99 on a biweekly basis •1 beginning February 26, 2007 and is ongoing. Fish detections are •3 mapped using a handheld GPS unit. •4

•3

• 1 tag detected above •11 •5 Camanche Dam during •2 •1 •7 •3 equipment test. Believed to One smolt stayed at the release site •1 •1 for 12 day then took 8 days to get be transported by a predatory to the Golden Gate. The other bird. stayed at the release site for 2 days •15 and traveled 14 days to the Gate. •2 •1 •1 •6 •8 •3 •8 •1 •1 •2 •2 •1 •2 PRELIMINARY CONCLUSIONS Map Legend Hatchery Smolts Reconditioned Kelts Wild O. mykiss • Hatchery Smolts • All were detected at least one time • All were detected at least one time • Sixteen were never detected • Kelts • 51% were last detected within one • Three remained in the lower • Stationary monitors detected 33%. An • Wild •2 month and in the vicinity of release site Mokelumne River and exhibited fine additional 40% were detected using «EBMUD Receivers •2 •1 • Last detections in the Mokelumne and scale movements detected in mobile mobile tracking techniques indicating •Other Agency Receivers Sacramento rivers suggest tracking wild fish moved relatively short •EBMUD release locations residualization or protracted movements • Two migrated to the Golden Gate distances from original capture and One kelt (female) stayed for 43 days • All available acoustic stations are not shown on map to the delta/ocean bridge in 57-81 days release sites. near the release site before reaching the • Not all detections are depicted on the map • Only three hatchery fish exhibited quick • One was captured by an angler within • 85% of those detected were last Golden Gate in 20 travel days. The other • The detections shown are the number of fish last detected at a movements to the Bay and Ocean a week of release detected above Hwy 99 in the lower (male) moved into the Delta immediately following release and specific site and represent the range of movement patterns • More data will be collected through Mokelumne River, implying a large stayed there for 33 days then traveled 11 exhibited by kelts, hatchery smolts and wild fish May 2008 resident population proportion days to the Golden Gate.