Crassostrea ariakensis: Non-native Oysters and the Chesapeake Bay - Chesapeake Bay Program

<p>Due to dramatic declines in the number of oysters living in the Chesapeake Bay and the seafood industry's eagerness to restore a viable local fishery, the possibility of introducing non-native species into the Bay's waters is being explored.</p> <p>Over the past century, harvests of the Bay's native oyster, <i><a href="american_oyster.cfm">Crassostrea virginica</a></i> or the Eastern oyster, have declined from more than 33 million pounds annually in the 1950s to 2.5 million pounds in 2000. While most of the historic decline is attributed to modern habitat degradation and overharvest, two diseases, Dermo and MSX, are considered the leading cause of native oyster mortality. </p> <p>Dermo and MSX were first discovered in the Eastern oyster in the 1950s. While the effects of MSX and Dermo are most acute in higher salinity waters found in the lower portion of the Bay, both diseases have expanded into less saline waters further up the Bay. Scientists believe MSX was inadvertently introduced to the Chesapeake Bay through importations of a foreign oyster, <i>Crassostrea gigas</i>, in the 1930s. </p> <p>In hopes of reversing declining populations of native oysters, <a href="../baypartners.htm" target="_top">Chesapeake Bay Program partners</a> are currently working with resource managers, researchers, policymakers and watermen throughout the Bay region to adopt a Baywide <a href="../cop.htm" target="_top">Comprehensive Oyster Plan</a> aimed at increasing native oyster populations tenfold by 2010. Scientists believe this goal, adopted as part of the <a href="../c2k.htm" target="_top">Chesapeake 2000 agreement</a>, will not only help jumpstart native oyster recovery, but will also lead to better water quality by increasing the number of oysters filtering the Bay's waters. Recovery of a thriving native oyster fishery, however, will be a much longer term project.</p> <h4>Introducing Non-native Oysters into the Bay</h4> <p>In hopes of re-establishing a Virginia commercial oyster industry, in 1995, the Virginia legislature directed the <a href="http://www.vims.edu" target="_top">Virginia Institute of Marine Science</a> (VIMS) to begin a study on non-native oyster species for introduction to the Chesapeake Bay. </p> <p>VIMS first began to study <i>Crassostrea gigas</i>, a popular and widely cultivated foreign oyster, in 1995. The studies used oysters in a triploid, or non-reproductive, form. The gigas results were unimpressive, showing inferior growth and survival in lower salinities compared to the native oyster. </p> <h4>Introducing <i>Crassostrea ariakensis</i></h4> <p><img src="../images/ariakensis2.jpg" align="right" alt="ariakensis">Once researchers determined gigas unsuitable for Bay waters, efforts began to focus on Asian Suminoe oyster, <i>Crassostrea ariakensis</i>. In limited field trials, ariakensis demonstrated lower mortality from Dermo and MSX, hearty and rapid growth, and success in taste tests. Researchers found ariakensis oysters grow to market size in only nine months as opposed to two years for virginica. This has resulted in increased pressure from the industry to adopt the non-native alternative.</p> <p>As of April 2002, approximately 60,000 triploid ariakensis oysters have been tested in the Bay. The Virginia Seafood Council has proposed to initiate industry trials with one million triploid ariakensis oysters in 2002. Due to the possibility of oysters reverting to diploid, or reproductive form, some scientists and mangers are concerned that the proposed industry trials could result in the establishing a free-living reproductive ariakensis population in the Bay. Such a non-native introduction could be an irreversible action, and some are concerned that it could significantly affect the health of the Bay ecosystem. </p> <p>Within the Bay community, there is an ongoing debate among those supporting immediate ariakensis introduction and those advocating further research before making a decision about introducing the species to the Bay.</p> <p>Some stakeholders, including the Virginia Seafood Council and some Maryland and Virginia watermen, view ariakensis as a promising solution to several problems, and strongly urge widespread introduction of sterile - or possibly even fertile - ariakenis oysters. Their view is that ariakensis could serve to revitalize the industry as well as provide the means for improved water quality through increased bio-filtration. Other potential benefits include a reduction of fishing pressure on the native oyster and the creation of hard substrate for further oyster attachment and reef development..Other stakeholders believe that ariakensis introduction needs to be approached with a high level of caution. Many are concerned about the species' disease-harboring capabilities including possible pathogens that could harm native populations of aquatic plants and animals. Others are concerned about food web effects that could alter benthic communities and ecosystems, while competition and reproductive interference with the native oyster may create additional pressures on already low virginica populations. Whether enough is known about the biology of ariakensis in its native range to effectively assess these benefits or risks at this time is the big question for managers.</p> <h4>Where Bay Experts Stand</h4> <p>With many facets of ariakensis ecology still unknown, scientists and managers are faced with the dilemma of responding to increased pressure to rebuild the oyster industry while insuring the protection and restoration of the Chesapeake Bay and its resources.</p> <p>Many institutions and organizations, such as the Chesapeake Bay Program's <a href="../fac.htm" target="_top">Federal Agencies Committee</a>, the <a href="http://www.cbf.org" target="_top">Chesapeake Bay Foundation</a> and the <a href="http://www.vims.edu" target="_top">Virginia Institute of Marine Science</a>, have developed position statements calling for more research on the potential impacts of ariakensis introduction. </p> <p>The implications of a non-native introduction are complex and difficult to understand. In June 2002, the <a href="http://www4.nationalacademies.org/nas/nashome.nsf" target="_top">National Academy of the Sciences</a> will initiate a one-year study that includes a review of the adequacy of existing science, risks, potential consequences and socioeconomic considerations.</p> <p>The National Academy of Sciences study is being funded by the <a href="http://www.chesapeake.org/" target="_top">Chesapeake Research Consortium</a>, <a href="http://www.seagrant.uconn.edu/" target="_top">Connecticut Sea Grant</a>, <a href="http://www.mdsg.umd.edu/" target="_top">Maryland Sea Grant</a>, <a href="http://www.nfwf.org/" target="_top">National Fish and Wildlife Foundation</a>, <a href="http://www.noaa.gov" target="_top">NOAA</a>, the states of Maryland and Virginia, <a href="http://www.epa.gov">U.S. EPA</a>, <a href="http://www.virginia.edu/virginia-sea-grant/" target="_top">Virginia Sea Grant</a> and <a href="http://www.fws.gov" target="_top">U.S. Fish and Wildlife Service</a>. </p> <div align="center"> <center> </center></div><div align="center"><center> <table border="1" cellpadding="5" cellspacing="0" bgcolor="#C6C68C" width="100%"> <tr> <td><strong>Other Sites of Interest:</strong> <ul> <li><a target="_top" href="http://www.mdsg.umd.edu/oysters/exotic/ariakensis.html">Maryland Sea Grant</a> - Info on <i>crassostrea ariakensis</i> (Suminoe Oyster) </li> </ul> </td> </tr> </table> </center> </div> <font SIZE="2"></font> <hr noshade> <p align="center"><font face="Times New Roman" size="2">To bookmark this page, please use this URL: <a href="http://www.chesapeakebay.net/ariakensis.htm" target="_top">http://www.chesapeakebay.net/ariakensis.htm</a></font></p> <p align="center"><font size="2">For more information, contact the Chesapeake Bay Program Office:<br> 410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800) YOUR-BAY / Fax: (410) 267-5777</font><font size="2">.</font></p> <p align="center"><font size="2"><a href="../termsofuse.htm" target="_top">Terms of Use</a> | <a href="../privacypolicy.htm" target="_top">Privacy Policy</a> | <a href="../comments.htm" target="_top">Contact Us<br> </a></font><font size="2"><a href="http://www.chesapeakebay.net/directions.htm" target="_top"> Directions to the Bay Program Office</a></font><br> <a href="http://www.chesapeakebay.net/cims" target="_top"><img src="../images/cims1.gif" height="19" width="51" border="0" align="left" vspace="10" alt="Chesapeake Information Management System (CIMS) "></a><a href="javascript:print()"><img src="../images/print.gif" width="31" height="38" border="0" alt="Print Current Page" align="right"></a><br> <font size="2">Last modified: 04/23/02</font> </p> </td> <td align="left" valign="top" bgcolor="#E7E7D6">   </td> </tr> <tr> <td align="left" valign="top" bgcolor="#E7E7D6"><img src="../images/endc3.gif" alt="endc3.gif (827 bytes)" WIDTH="8" HEIGHT="14"></td> <td align="right" valign="top" bgcolor="#E7E7D6" colspan="2"><img src="../images/endd3.gif" alt="endd3.gif (827 bytes)" WIDTH="8" HEIGHT="14"></td> </tr> </table>