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anglers accepted the commercial fishery that provided a considerable savings to the State by using personnel and nets that would have been provided by the State. Use of Weirs, Fishways, Fish Screens, and Barriers to Control or Guide Fish Natural Guidance of fish can be produced by light (or its absence), velocity, channel shapes, depth, sound, odor, and temperature. Individual fish or groups of fish may respond more readily to one particular stimulus, which can override others, i.e., the fish's instinct to move from areas of sunlight to shade, or their reluctance to move from their selected depth or velocity gradient, etc. Sea lampreys have been partially controlled in the Great Lakes by weirs on spawning tributaries. Weirs or barriers were most successfully used during migrations. It was generally unprofitable to operate them during other periods because of high labor cost. Fishways are man-made passages for fish over a hydraulic barrier. A fishway or fish ladder must be operable over a wide range of flow conditions and maintenance costs can be kept at a minimal through property design. (Sands, 1966). Some considerations for design of fishways include: 1. The entrance should be as close as possible to the places where fish will congregate near the barrier. 2. Entrance flows should be substantial enough to attract fish at all water stages. 3. Changes in direction should be minimized where fish will seim through water of high velocity. 4. Energy dissipation must be complete, with no carry over from pool to pool. 5. The fishway must provide adequate depth for swimming and turning. 6. Resting spaces should be adequate for the species. 7. Flow patterns in the fishway must be stable. 8. A debris deflector should be incorporated where the water enters the fishway. 9. Velocity should be controlled to prevent undesirable fish from congregating or spreading. 10. Everything feasible should be done to reduce the need for cleaning, regulating, repairing, and inspection. 5