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Fig. 10. Tom Burke, Bureau of Reclamation, refined hand-collec- tion techniques for razorback sucker larvae. Collection equipment includes a small meshed aquarium dip net, a halogen light and 12-vdc battery, wash tub, 5-gallon bucket, and a thermos of hot coffee. Larvae are individually netted by hand. CHLP. It was 100 times more productive (fish/hour) than passive netting techniques (table 4). However, as previously mentioned, recent studies suggest electrofishing can cause detrimental harm to all life stages (Muth and Ruppert, 1996, 1997; Snyder, 2003). If improperly used, strong electric currents can cause severe spinal injuries and even death to larger fish (fig. 12). Juveniles are seldom captured in the wild, and the only experience in their capture is at rearing facilities. Young suck- ers are inclined to enter hoop nets and large minnow traps, especially when disturbed and when other forms of cover are scarce (Ty Wolters, BOR, oral commun., 2004). Trammels are widely used but caution needs to be taken using gear that can accidentally "gill" fish. For example, small (10-12 cm) suckers are extremely susceptible to gilling in 1.2- cm trammel nets. Trammel nets were the second most effec- tive method and the most productive of the passive techniques used. Multifilament nets averaged 0.9 razorback suckers per hour year round. They are especially effective during the spawning season, when fish are congregated and active. The Fish 11 Fig. 11. U.S. Geological Survey biologists drain the contents of a floating light trap for future examinations. Light traps are effective in determining the presence of larvae. Researchers expended more than 1,600 hours of effort trying other, less stressful capture techniques but were unsuc- cessful in finding an effective substitute for either electrofish- ing or trammel netting. Researchers attempted baiting hoop nets and traps with dry dog food and canned cat food. While this increased catch, it also increased the incidence of crayfish and crayfish-related mortality for small entrapped fishes. In most instances, trammel nets are set overnight and checked in the morning. Adults seldom struggle, and netting abrasions and mortality are rare. During the Cibola study, 800 adult razorback suckers were captured without a single netting-related mortality. However, netting should be avoided during the summer. Subjecting fish to thermal or oxygen stress can result in chronic stress and lead to death.