<br />154
<br />
<br />Conservarion of Stream Fishes
<br />
<br />tive (Fig. 5) fish faunas are now connected by the Ten-
<br />. nessee-Tombigbee Waterway (Boschung 1987).
<br />lJthough mainstem impoundments on the Tennessee
<br />and Ientic environments associated with locks on the
<br />Tombigbee may limit dispersal of many stream fishes,
<br />the stage is set for invasions, hybridization, species re-
<br />placement, and ultimately a reduction in total species
<br />richness of the combined fauna (Preston 1962).
<br />
<br />Conclusions
<br />
<br />The common perception of all small non-game fishes as
<br />"minnows" and their existence in environments where
<br />few persons ever see them makes it difficult to muster
<br />public support for their conservation. In conflicts over
<br />development of increasingly valuable water resources,
<br />the fishes have few advocates. Beyond the serious issue
<br />of public awareness, however, lie other problems intrin-
<br />sic to river systems and their biota.
<br />In any species-rich fauna, most species are rare, and
<br />stream fishes are no exception (Sheldon 1987). In such
<br />cases reductions in the number of species by environ-
<br />mental stress or habitat fragmentation may be more pre-
<br />dictable than the identities of censored species, so fau-
<br />nal management, rather than a focus on single species, is
<br />required.
<br />~. - ,IIIT1llill' -LN~(Jllg.4} iftlPIf'fhatextDlc-
<br />~,.ffJIIOW'...enbltion. of ~...ne'MOtks.
<br />The impoundment of virtually the entire 1000 km
<br />length of the Tennessee River caused the disappearance
<br />of the minnow Hybognathus nuchalis from the entire
<br />system including tributaries not directly affected by res-
<br />ervoirs (Etnier et al. 1979). Other species may have
<br />been lost in some tributaries in the 50 years since con-
<br />struction began. Records and collections, as is inevitable
<br />when many rare species are involved, are probably in-
<br />adequate to fully document such. extinctions if they oc-
<br />curred. Both theory and experience with other taxa and
<br />habitats suggest that extinctions are inevitable.
<br />The' between-drainage component of fish diversity is'
<br />large (Fig. 5), but introductions and extinctions will
<br />eventually homogenize the fish fauna to the point where
<br />much of the variety and evolutionary history has been
<br />lost. Prohibition of interbasin transfers of water and
<br />more effective controls on introductions could greatly
<br />slow this process. "-
<br />The geometry of rivers further complicates preserva-
<br />tion. Rivers are open, directional systems so protection
<br />of any segment requires control over the entire up-
<br />stream network and the surrounding landscape. There is
<br />little likelihood that such protection can be given to
<br />very many streams of order 4 or higher, yet it is these
<br />streams that support the greatest diversity of fishes. Op-
<br />timistically, some degree of riparian control and preven-
<br />tion of industrial and agricultural pollution, channeliza-
<br />
<br />Conservation Biology
<br />Volume 2. No. 2. June 1988
<br />
<br />"I1t:/uUJ/
<br />
<br />tion, and impoundment may be sufficient to maintain
<br />diverse assemblages. Still larger streams, such as the
<br />Tennessee, have been irreparably modified. ._.:Jtl...1
<br />tiQll dfGrtsltrouklbe.focuscd.oa thc.....~..
<br />naturaldrainages in as manyttlajor river~as~;
<br />sible.';McDowall (1984) and Maitland (1985) suggest
<br />useful criteria for site selection and protection of fresh-
<br />water fishes. However, the size of North American rivers
<br />and the diversity of their fishes make the problems far
<br />more difficult. (Buck Creek [Cicerello & Butler 1985]
<br />supports more native fishes than the British Isles.)
<br />A comprehensive plan for the conservation of North
<br />American fishes lies in the future. A biogeographic over-
<br />view, as opposed to piecemeal species management, is a
<br />necessary component of such a plan although single-
<br />species management is compatible with a more inclu-
<br />sive approach since streams containing rare species of-
<br />ten support diverse assemblages. The conservation of
<br />fishes is also compatible with the protection of other
<br />organisms, such as molluscs and crayfishes, and of ripar-
<br />ian vegetation, water quality, amenity, and the entire
<br />spectrum of values of runiling-water ecosystems. .......t
<br />~.w*kh.of fithes.dlIt.80 ~. Da'Wd ~
<br />Starr j(xdm (1922) and eadietsclentiStS Is an impoifmt I
<br />compmr.ent oftbatvatue spectrum.'
<br />
<br />Acknowledgments
<br />
<br />Peter Moyle and Jim Williams made helpful comments
<br />on the manuscript. DeWayne Williams prepared the fig-
<br />ures. Dave Etnier, Herb Boschung, and the Corps of F;p.-
<br />gineers, U.S. Army, provided information and slides for
<br />the oral presentation of this material. I thank them all.
<br />
<br />Literature Cited
<br />
<br />Balon, E. K, S. S. Crawford, and A. Lelek. 1986. Fish communi-
<br />ties of the upper Danube River ( Germany, Austria) prior to the
<br />new Rhein-Main-Donau connection. Environmental Biology of
<br />Fishes 15:243-271.
<br />
<br />Bermingham, E., and). C. Avise. 1986. Molecular zoogeogra-
<br />phy of freshwater fishes in the southeastern United States. Ge-
<br />netics 113:939-965.
<br />
<br />Boschung, H. T. 1987. Physical factors and the distribution and
<br />abundance of fishes in the upper Tombigbee River system of
<br />Alabama and Mississippi, with emphasis on the Tennessee-
<br />Tombigbee Waterway. Pages 184-192 in W.). Mat,thews and
<br />D. C. Heins, editors. Community and Evolutionary IEcology of
<br />North American Stream Fishes. University of Oklahoma Press,
<br />Norman, Oklahoma.
<br />
<br />Brown, c.). D. 1971. Fishes of Montana. Big Sky Books,
<br />Bozeman, Montana.
<br />
<br />Cicerello, R. R., and R. S. Butler. 1985. Fishes of Buck Creek,
<br />Cumberland River drainage, Kentucky. Brimleyana 11:133-
<br />159.
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