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<br />Table 2. Predation rates on razorback sucker by potential predators tested in 2004. Predation is <br />mean number of prey consumed; all tanks began with 20 prey. <br /> Mean predation rate Instantaneous <br /> per tank (number of predation rate (number <br /> prey consumed out of of prey consumed! <br /> 20 prey items) predator/hr) <br /> N Duration <br /> (# oftrt x:!:: x:!:: of trial <br />Predator tanks) SE 95% CL SE 95% CL (hr) <br />Razorback sucker <br />eggs <br />Crayfish 6 14.8:c 2.8 7.7-21.9 1.12:c 0.22 0.55 - 1.68 6 <br />Bullfrog tadpoles 6 8.7:c 1.2 5.5 - 11.8 0.03 :C 0.004 0.02- 0.04 72 <br />Razorback sucker <br />larvae <br />Bullfrog tadpoles 7 5.6:c 1.0 3.1-8.1 0.02 :C 0.004 0.01 - 0.03 72 <br />Threadfin shad 5 2.0:c 1.1 0.0- 5.2 0.02:c 0.01 0.00 - 0.05 24 <br />Common carp 6 14.3 :C 3.3 5.9 - 22.8 0.17:c 0.04 0.07 - 0.27 24 <br />Green sunfish 5 20.0:c 0.0 20.0 - 20.0 0.21 :C 0.00 0.21 24 <br />Channel catfish 5 14.0:c 1.8 8.8 - 19.1 0.15 :C 0.02 0.09 - 0.20 24 <br />Fathead minnow 5 1.5 :C 0.9 0.0 - 2.4 0.02:c 0.01 0.00 - 0.04 24 <br /> <br />5. MISCELLANEOUS ACTIVITIES <br /> <br />Aging-Scale samples (150) were collected from both small bonytail and razorback sucker to <br />help determine year class structure and recruitment rates. We have been unable to determine <br />annual growth rates for young-of-year due to the extreme variability of sizes. There is some <br />evidence that limited spawning may also occur in the fall or that growth is much slower than <br />initially thought (Douglas et aI. 2000). We have collected YOY bonytail as small as 35 mm and <br />10 cm razorback sucker. If spawned during their normal reproductive cycle, these fish would <br />have been 10 to 12 months old. <br /> <br />Scales will be mounted, processed and read by Dr. Dennis Scarnecchia, at the University of <br />Idaho Coop Unit located in Moscow, Idaho. Results will be presented in the final report. <br /> <br />Telemetry-Dr. Paul Marsh organized a field trip to test new radio transmitter technology at <br />CHLP. These new transmitters weighed 0.8 g and were suitable for use on small fish. <br />Unfortunately, water conductivity (> 1 ,000 IlS) made the transmitters totally ineffective. At a <br />depth of only 1 m, transmission could only be detected at a maximum range of 20 m and when <br />lowered to 2 m, no signal could be heard at all. Future work will have to be accomplished using <br />the acoustic transmitters that we have used in the past. <br /> <br />Underwater Video-The underwater video camera was used on three occasions, twice at CHLP <br />and once at Willow Beach National Fish Hatchery. At CHLP, 12 hours of razorback sucker <br /> <br />16 <br />