(Melamita deglandi), about 70 percent of their 

 stomach contents consisted of oysters. The 

 number of birds in the Olympia Bay of Puget 

 Sound during the 2-week period of daily observa- 

 tions (November 16-29, 1928) averaged 2,000. 

 Together the three species of ducks were destroy- 

 ing about 8,000 oysters per day and causing ma- 

 terial damage to the small oyster industry of the 



area. 



The effect of predators on an oyster population 

 can be evaluated by determining the percentage 

 of oysters killed. 

 Man 



Among the highly destructive predators of 

 oysters, man occupies the most prominent posi- 

 tion. Long before our era the stone age dwellers 

 of the coast of Europe subsisted primarily on 

 shellfish which they gathered from shallow water 

 by wading and hand picking. The American 

 Indians used oysters and clams for food, and 

 dried and smoked shellfish meat for the food 

 supplies which they took on their travels. On 

 both continents numerous shell heaps or so-called 

 kitchen middens dot the coastline and indicate 

 the locations of primitive habitations or camp 

 sites. A famous shell heap on the banks of the 

 Damariscotta River, Maine, and many others 

 are evidence of the former productivity of the 

 oyster beds of past centuries. With the develop- 

 ment of oyster fishing gear, man became able to 

 gather oysters much more efficiently and extended 

 his efforts to deeper water. Oyster dredges of 

 various designs and dimensions remained for a 

 long time the principal and very effective gear, 

 until the appearance in the last quarter of a 

 century of various mechanical suction pumps and 

 other harvesters of much greater efficiency. 



With tlie improvement of fishing methods, the 

 oyster bottoms of the northern States became 

 overfished and many were depleted. This was 

 the fate of many oj^ster grounds along the shores 

 of the Gulf of Maine, in New Hampshire, Massa- 

 chusetts, and Rhode Island. In colonial times 

 the earliest white settlers of New England feared 

 the disappearance of their favored seafood and saw 

 the necessity of protecting their shellfish resources 

 by such legislative measures as restricting the size 

 of catch and prohibiting the selling of o_ysters out 

 of town. The results were ineffective, and many 

 oyster bottoms, particularly in the northern part 

 of New England, were destroyed. 



The world's richest oyster bottoms in the Chesa- 

 peake Bay suffered a similar fate, but the deple- 

 tion was more gradual and not as complete as in 

 more northern waters. Regulations prohibited 

 power dredging and set aside certain areas for 

 the use of tongers only, but they were not sufficient 

 to maintain the productivity of the oyster bot- 

 toms. Tlie production of oysters continued to de- 

 cline because of a general disregard of the basic 

 conservation principle that the sustained yield of 

 any renewable natural resource can be maintained 

 only if the quantity removed does not exceed the 

 quantity restored annually by reproduction and 

 growth. Throughout the world the shellfish 

 resources are depleted when more are taken than 

 nature is able to replace. 



Man must be regarded, therefore, as the most 

 dangerous predator. On the other hand, through 

 his action the productivity of an oyster bottom 

 can be brought to the highest level. Since ancient 

 times it has been known that oysters can be propa- 

 gated and cultivated. The development of oyster 

 culture in this country was particularly successful 

 in the waters of Long Island Sound where the 

 depleted shellfish resources were not only restored 

 by oyster farming, but many thousands of acres 

 of previously barren bottom were converted into 

 productive farms under water. Thus, man as an 

 ecological factor appears in a dual capacity — as 

 a primitive destructor and as a progressive culti- 

 vator. LTnfortunately, at present Long Island 

 Sound is no longer a highly productive oyster 

 farming area. The decline may be attributed to 

 poor setting, low survival rate of young oysters, 

 devastation caused by several hurricanes, and the 

 high cost of farming operations. 



At present the knowledge of oyster biology has 

 advanced to such a level that effective methods 

 can be employed both for sound management of 

 natural, wild populations of oysters, and for de- 

 velopment of highly productive farms for breeding 

 selected strains of oj'sters. The continuous decline 

 of oyster beds is due not to a lack of knowledge 

 but to failure to apply it. 



Aquatic resources of tlic tidal areas along the 

 Atlantic and Gulf coasts of the United States are 

 threatened by human activities other than over- 

 fisliing. Many formerly productive areas of the 

 coast have been damaged beyond reconstruction 

 by the filling of marsh lands for industrial sites, 

 by the construction of thruways, marimis, real 

 estate developments, and trash and garbage dis- 



440 



FISH AND WILDLIFE SERVICE 



