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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 <br />adjustable waterfalls for evaluating fish jumping <br />performance. Transactions of the American Fisher- <br />ies Society 134(2):503 -508. <br />Moyle, P. B., R. M. Yoshiyama, J. E. Williams, and E. <br />D. Wikramanayake. 1995. Fish species of special <br />concern in California. Department of Wildlife & <br />Fisheries Biology, University of California, Davis, <br />Report # 2128IF, Davis, California. <br />Myrick, C. A., and J. J. Cech. 2000. Swimming perfor- <br />mances of four California stream fishes: tempera- <br />ture effects. Environmental Biology of Fishes <br />58(3):289 -295. <br />Peake, S., F. W. H. Beamish, R. S. McKinley, D. A. <br />Scruton, and C. Katopodis. 1997. Relating swim- <br />ming performance of lake sturgeon, Acipenser <br />fulvescens, to fishway design. Canadian Journal of <br />Fisheries and Aquatic Sciences 54:1361 - 1366. <br />Schlosser, I. J., and P. L. Angermeier. 1995. Spatial <br />variation in demographic processes of lotic fishes: <br />Conceptual models, empirical evidence, and im- <br />plications for conservation. Pages 392 -401 in J. L. <br />Nielsen, editor. Evolution and the aquatic ecosys- <br />tem: defining unique units in population conser- <br />vation, volume 17. American Fisheries Society, <br />Bethesda, MD, USA. <br />Winston, M. R., C. M. Taylor, and J. Pigg. 1991. Up- <br />stream extirpation of four minnow species due to <br />damming of a prairie stream. Transactions of the <br />American Fisheries Society 120(1):98 -105. <br />