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studies have shown a strong correlation between survival and size of fish when released. First-year survivorship for fish 30 cm long was 10 percent, compared to 26 percent for fish released at 35 cm (Marsh and others, 2005). The Lake Mohave Native Fish Work Group (NFWG) is an interagency program that is reintroducing razorback suckers in Lake Mohave. They recently recommended increasing the targeted stocking size from 35 to 50 cm for Lake Mohave. Even fish at this size remain vulnerable to large (>20 kg) striped bass (Morone saxatilis) and flathead catfish (Pylodictis olivaris) that are found in the system. There are also other issues in producing larger fish: it increases production costs (per fish) and decreases production numbers. It is unknown whether this change in stocking strategy will help increase populations. Terrestrial researchers have recognized for several decades the importance of survival skills in the animals and birds used in repatriation programs. Current programs not only train, but test the performance of repatriated animals and birds in natural food recognition, foraging ability, and avoidance behavior to predators and humans prior to release. These survival approaches have proven critical in the reintroduction of the gray wolf (Canis lupus), California condor (Gymnogyps california), masked bobwhite quail (Colinus virginianus ridgewayi), and blackfooted ferret (Mustela nigripes) (Ellis and others, 1978; Fritts and others, 1997; Biggins and others, 1998; Bangs and others, J 998). Similar approaches have been adopted by Pacific Northwest salmon augmentation programs. Maynard and Flagg (2001) developed the Natural Rearing System (NATURES) program that incorporates naturaJ feeding, physical conditioning, and predator recognition to improve post-stocking survival. However. similar research or culturing approaches are rare for warm-water species. Mueller and others (2003) found that exercised razorback sucker were less prone to downstream dispersal compared to pond reared fish and Ward and Hilwig (2004) reported bony tail and razorback sucker exercised for two weeks exhibited greater swimming stamina than non-exercised fish. We proposed that if swimming performance was improved, it may also improve predator avoidance skills. The goal of this study was to test whether physical and/or behavioral conditioning would improve predator avoidance skills for bony tail and razorback sucker. Methods The study was conducted at Achii Hanyo, a satellite hatchery facility of Willow Beach National Fish Hatchery (Willow BNFH). The facility is located near Parker, Ariz., and is operated by the U.S. Fish and Wildlife Service (FWS). Bony tail and razorback suckers were supplied by Willow BNFH. We used largemouth bass (Micropterus salmoides) as the predator for bony tail and flathead catfish (Pylodictis olivaris) as the predator in razorback sucker experiments. Study predators were collected from the Colorado River and returned unharmed following the study. Surviving native fish were included in native fish stockings elsewhere. The study involved treatment, testing, and observation elements. Treatment activities involved exercising and exposing trial groups to predation prior to the actual predator/prey trials. The swimming performance of exercised and unexercised fish was measured using a flow chamber. Survival performance was determined by placing treated and control groups in large tanks with predators to actually measure predation rates. Working at the fish facility gave us a rare opportunity to spend considerable time observing these fish and conducting impromptu side experiments. Those observations and informal experiments are included in this report. 2