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alone did not trigger predator avoidance; prey had to associate pn:dalnr odors \\ Ilh Illl' \ 1<l1I11\:111',. \! (Brown and Smith, 1998; Brown and Godin. 1999). Predator d\Ulddlh.l' i" ;kl\I,;I/I ,[ I.,l'i'.," that is inhibited in present-day culturing programs. We believe r!oV\. el)ndJllunJng .Ind 1111111,',11'1";,\1 'I exposure could improve short-term survival rates of hatchery-reared bony tail alld ralOrhac" slIdl'l Additional research is needed to help develop methods of mass exposure. determining IhL' duratlllll III the learned response, and the duration and velocity of flow regimens for optimal phYSical L'ondlllulllllg These efforts should be followed by, or run concurrently with, the release of a large numher oflrL'dll'd fish in the wild to determine actual predation rates. Conclusions We provide conclusive evidence that behavioral and physical conditioning can illlPlll\ c thl' performance of bony tail and razorback suckers over their hatchery cou n terparls The major COlh.' 1I \ I UI]\ drawn by this study are the following: · Hatchery reared bony tail and razorback sucker are naIve to the predator threat by largemouth bass and flathead catfish. · At initial contact, hatchery raised bony tail and razorback suckers freely approach predators. · Predator avoidance is a learned behavior. · Predation losses were reduced for flow-conditioned razorback sucker. · Predation losses were reduced for razorback sucker having a previous predator cxpcr;L'ncL' · Predation losses were reduced for bony tail having a prevIous predator CXpellL'llll' · All treatments (exercise and predator exposure) resulted In IL'duced pIl'ddll\ '11 Ii "",', A great deal was learned, but we also generated quill' a few new 4Uesl10lh lhdl Lk"el\ L' 11I11!ll'l investigation. Unfortunately, we simply do not know if this type of conditioning would 1I1ned\L' SlIlIl \;11 in the wild. Further research is justified to examine the predator/prey interactions 111 the field dillllu further refine predator avoidance and exercise techniques in hatchery settings Some of (llose qlll'slll 1/1, include the following: · How long is predator avoidance retained? · What is the most effective way of mass exposing treatment fish to predators') · What predators should be used? · What is the optimal duration and velocity for flow conditioning') · What is the actual survival benefit in the wild? · What is the economic savings? Acknowledgments We want to extend our appreciation to the FWS for supporting this research and providing the necessary facilities and fish and to USGS for funding under the Science Support Program. We thank Dr. Paul Marsh (Arizona State University) and Charley Land (Colorado River Indian Tribes) and their respective staffs for assistance in collecting predators. Farley and Tuba Krapfel providedsecuJ'Jl\ ,\ \ I work was conducted under Federal permits held by Willow Beach National Fish IJatLlwl\ ~1I1l1 'iLlll permits held by Gordon Mueller. 22