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pulsed DC by a Coffelt@ WP-15 or Coffelt Mark 20 Complex Pulse System (CPS TM) electrofishing control unit. Settings for the WP-15 were 60 Hz and 24% duty cycle (4-ms pulses). These settings a:-e commonly used with the WP-15 in boat electrofishing for adult razorback sucker in the middle Green River system (E. Wick, U.S. National Park Service, personal communication). The CPS unit, a newer and potentially less harmful control unit (Fredenburg 1992; Sharber et al. 1994), produces a fixed complex-pulse pattern consisting of 15-Hz "packets" of three 240-Hz, 2.6-ms pulses which results in a 12% duty cycle. Each control unit was set at 200 V, and output was measured at 0.45 A. Typical output from a WP-15 during electrofishing on the Green and Colorado rivers, Utah, at conductivities of 300-600 pS/cm is 200-300 V and 5-7 A (T. Chart, Utah Division of Wildlife Resources, personal communication). The treatment chamber was a 227 -cm long X 53-cm wide X 53-cm deep fiberglass tank with full cross-sectional, steel-plate electrodes placed parallel 191 cm apart to provide homogeneous electric fields with a peak-voltage gradient of 1.0 V/cm as measured by an oscilloscope. According to data summarized by Snyder (1992), a peak-voltage gradient of 1.0 V/cm should be sufficient to induce at least narcosis in many fishes. Water in the tank was 47 cm deep, 20oC, and had a conductivity of 610 pS/cm which approximated mean conductivity in the Green River near razorback sucker spawning areas upstream of Jensen, Utah, during late April through May I the period when peak spawning of razorback sucker usually occurs (T. Modde, U.S. Fish and Wildlife Service, personal communication). A plastic-mesh holding basket, 90 cm long X 38 cm wide X 37 cm deep, was suspended midway between the electrodes to confine fish during treatment and keep them away from the electrodes and treatment-chamber walls and bottom. Treatment with either current was replicated twice, and each replicate consisted of two males and two females, except for one replicate subjected to CPS that consisted of two males and one female. There was one control consisting of two males and two females. Each group of fish was randomly assigned to treatments or control. Control fish were handled the same as shocked fish but without exposure to electric current. Fish in each treatment replicate were placed one at a time in the holding basket with their head toward the anode and subjected to either current for 10 s, an exposure time used in other investigations (e.g., Dwyer and White 1995) and that might be at least occasionally expected when electrofishing. Observations were made on fish behavior and condition before and during treatment. Immediately before and after treatment, each fish was examined . for external evidence of hemorrhaging (bruises or brands). Gametes were manually stripped from fish in each treatment replicate or the control and combined for egg fertilization. Samples of eggs were taken before fertilization and immediately after water hardening and preserved in 10% formalin. Subsamples of these eggs (N = 50) were later examined for evidence of obvious 6