Abstract: An electric fish barrier for deterring fish from entering a water intake in a reservoir or along a waterway has a set of conductive members at a first voltage potential and a second set of conductive members at a second voltage potential. The conductive members are disposed on support piles extending up from the bottom of the reservoir. Each conductive member extends vertically between a pre-determined range of depths from an upper depth to a lower depth, forming a contiguous voltage gradient between the two sets of conductive members. Fish are drawn to the attraction flow of water flowing into the intake. The two sets of conductive members are oriented such that the attraction flow passes through the contiguous voltage gradient, thereby deterring the fish from following the attraction flow into the water intake.

Abstract: A variety of electrified fish barriers are suitable for diverting fish from protected structures, e.g. pump intakes. Most take the form of linear curtain arrays (i.e. arrays of fixedly spaced-apart vertical elements). Many are characterized by the use of three or more pulsed driving signals of different voltages. This results in an electrical field pattern that extends broadside of the array, permitting fish an opportunity to turn and swim away before reaching a dangerous field strength. One barrier advantageously integrates the electrodes with a physical control structure that can be used to equalize the through-barrier water flow along its length. Others employ sets of electrodes that are driven in staggered, time-multiplexed fashion so as to reduce peak power requirements. Barriers used to screen pump intakes on the sides of flowing waterways are desirably sized and placed so that the velocity of water flow through the barrier is one-half, or less, of the waterway bypass flow adjacent the barrier.

Abstract: An electrofishing method and apparatus employs programmable hardware to generate output waveforms that will stun or alter the behavior of fish while minimizing the harm done to the fish. By programming a variety of instructions into the programmable hardware, a wide range of different output waveforms can be produced. The programmable hardware can also monitor environmental conditions to automatically adjust and optimize the waveform parameters. Finally, the programmable hardware can be interconnected by a data network to form an array of charged electrodes, with each output related and synchronized in a predetermined way for use in electric fish barriers and guidance systems.

Abstract: An electric barrier for discouraging the passage of fishes through a natural or artificial waterway, or for repelling fishes from the vicinity of an underwater structure in a waterway. A submerged electrode array is provided for electrifying at least a portion of a waterway when energized by a plurality of electric pulse generators. The outputs of the pulse generators are connected in series and each is also connected to a separate electrode of the array so that when synchronously triggered, the outputs are in phase and additive in amplitude along the electrode array. In a preferred embodiment of the invention, each pulse generator is adjustable in output amplitude so that the electric field gradients along the electrode array can be adjusted to minimize the injury to fishes repelled by the barrier.

Abstract: A method of etching a plurality of identifying characters into a wire tag for macro-organisms is disclosed. The method includes the steps of coating the tag with photoresist, exposing a defined portion of the coated tag to light, the defined portion corresponding to the characters, removing a portion of the photoresist, with that removed portion also corresponding to the characters, and etching the uncoated portion of the tag. Thus, a pattern will be etched into the tag which corresponds to the characters. This provides a means for rapidly, inexpensively, and indelibly marking wire tags in a manner which is superior to the methods proposed in the prior art.

Abstract: A system for implanting a magnetizable tag into a macro-organism is provided. The system includes an organism receiving element for receiving an abutted surface of the macro-organism, a mechanism for advancing the tag toward the receiving element, a guide annulus for providing an injection path of travel and a magnet for magnetizing in alignment with the path of travel, and a magnet for magnetizing the tag as it is passed through the guide annulus. In one aspect of the invention, the guide annulus comprises a tubular member having a blunt implantation end for abutment with the macro-organism at the moment of implantation.