Fish Passage Restoration

<body> <p>The great rivers of the <a href="../wshed.htm" target="_top">Chesapeake Bay watershed</a>-the Susquehanna, Rappahannock, Potomac, York and James-supply nearly 90 percent of the Bay's fresh water and are the lifelines of the Bay's seven major migratory fish species: </p> <ul> <li><a href="../american_shad.htm" target="_top">American shad</a></li> <li>hickory shad</li> <li>alewife</li> <li>blueback herring</li> <li><a href="../white_perch.htm" target="_top">white perch</a></li> <li><a href="../striped_bass.htm" target="_top">striped bass</a></li> <li>yellow perch</li> <li><a href="../american_eel.htm" target="_top">American eel</a></li> </ul> <p>Striped bass, shad, herring and perch are anadromous fish, which spend much or all of their adult lives swimming in the ocean and must travel up freshwater rivers and streams to spawn. American eels are catadromous, and travel in the opposite direction, spending their adult lives in the brackish waters of the estuary then travelling to the Sargasso Sea to spawn. Both migrations require open passage along the watershed's complex network of rivers and streams.</p> <p>Larval fish also depend on the rivers' movement and water quality for adequate sustenance and the shelter of aquatic plants, and to send them downstream, where many eventually enter the Bay and open ocean.</p> <h4>River and Stream Blockages</h4> <p><img src="../images/blockage.jpg" alt="Fish Blockage" align="right" width="242" height="123">Anadromous fish were once the basis of an enormous commercial and recreational fishery throughout the Chesapeake Bay watershed. Today many anadromous species are nearly nonexistent in the upper reaches of the watershed, because streams and rivers are blocked by dams, road culverts, bridge aprons and other structures. </p> <p>For the past 100 years dams have been constructed in the United States and throughout the Chesapeake Bay watershed, for irrigation, water storage, hydroelectric power and flood control. According to American Rivers, about 75,000 dams larger than six feet exist along the United States's waterways. More than 2,500 dams and smaller blockages occur in the Bay watershed.</p> <p>Where healthy rivers connect habitat and promote species diversity and a thriving Bay system, dams and blockages disconnect and disrupt. Dams fragment and isolate river corridors and may convert flowing waters into still waters, forcing their respective native species of plants and aquatic animals to adapt or give way to species that have other requirements.</p> <p>Dams alter thermal conditions and have an impact on salinity, which can affect the reproduction of aquatic plants and animals. The dams and blockages in the Bay watershed have contributed to an 82 percent decline in the commercial harvest of anadromous fish in the Bay between 1976 and 1985. Virginia and Maryland placed moratoria on several species to reduce fishing pressure, but spawning habitat must continue to be restored. </p><h4>Removing Dams</h4> <p>In some cases, removing dams rather than providing passage over them is safer for the fish-it lowers the risk of mortality to species that must pass them to spawn. </p> <ul> <li>Many dams have no fish passage structures, and in some cases fish can still be injured in the process of moving through fish passages. </li><li> Predation of some species is higher in the area below fish ladders as fish wait to move up the structure. </li><li> In the case of American shad, delays caused by the fish passage process may prevent them from releasing eggs or sperm before returning to the ocean. </li><li> Small fish have difficulty negotiating passages designed for large fish, while large fish such as Atlantic sturgeon cannot use the passage at all. </li> </ul> <p>In such cases, removing the dam or breaching may end up being the preferred solution.</p> <p>Learn about <a href="fishpass_options.cfm">fish passage that works</a></p> <div align="center"> <center> <table border="2" cellpadding="2" cellspacing="0" bgcolor="#FFFFFF" width="100%"> <tr> <td><a name="What YOU can do:"><strong>What YOU can do:</strong></a> <ul> <li>Help clean and maintain fish passages.</li> <li>Encourage your local and state governments to facilitate construction of fish passages.</li> <li>Remove old dams that are no longer used and are on your property.</li> <li>Support strong management actions to allow stocks to increase and prevent over-fishing.</li> </ul> </td> </tr> </table> </center> </div> <div align="center"> <center> </center> </div> </body>