Changes in hard clam, Mercenaria mercenaria, fisheries of the Mid-Atlantic region in response to stock fluctuations

The processes by which the hard clam, or northern quahog, Mercenaria mercenaria, are being produced in the mid-Atlantic region have changed dramatically in the past twenty years. Wild harvest in approved waters is often replaced by relay programs, shellfish depuration, and clam aquaculture. These activities are the response by the commercial industry to stock reductions in approved water. Since participation by the commercial sector is linked to landings and harvest price, the number of clammers fluctuates also. Reasons for changes in relative abundance in coastal areas are speculative, but increased human populations, use of estuarine waters for cooling of electric generating plants, increased use of copper in dock building materials and antifouling paint, and the rise of outboard engine use are most often identified by the commercial industry as the most probable causes. Even in areas of intense clam aquaculture, there are no significant examples of new clam sets. Since there are no obvious reasons for stock reductions, it is imperative that an ad hoc group of industry members, extension personnel and shellfish researchers be established to focus effort on identifying causes of stock reductions and ways to improve them, whether through stock enhancement, public aquaculture, or habitat improvement.