ments occur. Once the fishes of interest are identified,
<br />data on their swimming performance is needed. The
<br />most useful information on swimming performance
<br />takes the form of species - specific swimming veloc-
<br />ity vs. endurance curves that show how long fish of a
<br />known size can maintain a range of different swim-
<br />ming velocities (Katopodis 1994; Peake et al. 1997).
<br />These curves can be used by engineers to determine
<br />whether a fish, swimming at speed Y, will be able to
<br />cover a known distance (such as the length of a culvert)
<br />through which the water velocity is known, before
<br />it fatigues and is swept back downstream. In order
<br />to generate such a curve, a fish physiologist needs to
<br />measure the swimming performance of the species of
<br />interest at a wide range of speeds, from the fish equiva-
<br />lent of a slow walk to the equivalent of a sprint. Ad-
<br />ditionally, because of the well - documented effects of
<br />temperature and fish size on swimming performance
<br />(Myrick and Cech 2000), the studies should also be
<br />repeated for the range of water temperatures the fish
<br />are likely to encounter and for a realistic range of sizes.
<br />Studies of this nature are not technologically difficult,
<br />and can be performed in a standard fish physiology
<br />laboratory using a variety of swimming flumes. These
<br />studies are time - consuming, because of the number of
<br />variables that have to be tested, but they represent the
<br />best method of developing performance curves that are
<br />easily understood by fishery biologists and engineers
<br />alike.
<br />Once suitable performance curves are available, fishery
<br />biologists and engineers should work together to de-
<br />velop a fishway design that affords maximum upstream
<br />access to the fishes of concern while meeting the con-
<br />straints imposed by the site - specific topography, flow
<br />requirements, the original purpose of the structure, cost,
<br />and intrinsic values such as appearance. Compromises
<br />may have to be made in most cases (e.g., recognizing
<br />that passage of fish under a certain size will be im-
<br />paired, or releasing slightly higher flows to ensure that
<br />the fishway is functional), and the decision on where
<br />those should fall will not be an easy one. Resource
<br />managers, stakeholders, and society at large will have
<br />to place a value on restoring ecological connectivity
<br />and weigh the costs and benefits of such efforts, while
<br />keeping in mind that adding fish passage structures
<br />cannot along restore a river to a natural state.
<br />18
<br />References
<br />Clay, C. H. 1995. Design of fishways and other fish
<br />facilities., 2nd edition. Lewis Publishers, Boca
<br />Raton.
<br />Helfrich, L. A., C. Liston, S. Hiebert, M. Albers, and
<br />K. Frazer. 1999. Influence of low -head diversion
<br />dams on fish passage, community composition,
<br />and abundance in the Yellowstone River, Montana.
<br />Rivers 7(1):21 -32.
<br />Katopodis, C. 1994. Analysis of ichthyomechanical
<br />data for fish passage or exclusion system design.
<br />Pages 318 -323 in D. D. MacKnnlay, editor High
<br />Performance Fish. Fish Physiology Association,
<br />Vancouver, BC.
<br />Kondratieff, M. C., and C. A. Myrick. 2005. Two
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<br />Moyle, P. B., R. M. Yoshiyama, J. E. Williams, and E.
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<br />concern in California. Department of Wildlife &
<br />Fisheries Biology, University of California, Davis,
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<br />Peake, S., F. W. H. Beamish, R. S. McKinley, D. A.
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