Fish Passage
Fish passage technologies are intended to promote movement of fish, often between Great Lakes and their tributaries. Some technologies, such as fish lifts and trap and transfer passage, are passive. Other technologies, called fish ladders, are waterways that provide fish the opportunity to pass a barrier by swimming or leaping through an engineered waterway . Effectively passing desired fish species through, over, or around a barrier requires an understanding of the behavior of fish (those that will and will not be passed) and an understanding of river flow conditions and habitat. This means biologists and engineers must work together on design if a structure will have any success in passing fish. Although fish passage technology continues to advance, the development of a method to allow both up- and downstream passage of only desirable species remains a challenge to both biologists and engineers.
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The Great Lakes Fishery Commission, in supporting restoration of aquatic habitat connectivity throughout Great Lakes watersheds but requiring blockage for sea lampreys at lowermost barriers critical to sea lamprey control, is investigating bidirectional selective passage technologies that achieve both objectives.