THE OYSTER INDUSTRY OF THE WORLD 565 



control of Urosalpinx consist of trapping or dredging with a special drill dredge 

 (GaltsoflF et al., 1937). No method of controlling Tritondia has yet been devel- 

 oped, except that of burning with flame torches the egg cases laid on submerged 

 structures exposed at low water. 



The No. 2 oyster enemy is the starfish {Asterias forbesi Desor), which inflicts 

 heavy damages to oysters in Narragansett Bay and Long Island Sound. Two 

 methods of control are available: mopping the grounds with tangles and sprin- 

 kling the infested areas with finely powdered unslacked lime (Loosanoff and 

 Engle, 1942). Control of individual grounds is, however, ineffective and ex- 

 pensive because the nearby areas remain unattended (Galtsoff et al., 1939). In 

 Long Island Sound and Narragansett Bay the centers of infestation from which 

 the starfish spread to adjacent bottoms are abandoned private grounds and de- 

 pleted public reefs. Starfish larvae swim freely and are carried by tides and cur- 

 rents over a large area. Efforts of the United States Fish and Wildlife Service 

 to persuade the oyster growers to join forces and attack the centers of starfish 

 population rather than to attempt to control them on their individual lots so far 

 have been fruitless. 



Of the other enemies of lesser importance mention should be made of the bor- 

 ing sponge (Cliona) and boring clam (Martesia) , which attack the shell of the 

 oyster, the drumfish (Pogonias) , and various species of skates (Raja), which feed 

 on mollusks and occasionally destroy large numbers of oysters. Many sedentary 

 organisms that attach to the shell of the oyster, such as mussels (Mytilus), slip- 

 per shells (Crepidula), barnacles (Balanus, Chtamidiis) , and many others occa- 

 sionally become very troublesome. The slipper shell (Crepidula) , introduced with 

 the eastern oyster to the Pacific Coast and to Europe, causes much more serious 

 trouble by overcrowding planted oyster grounds in the new environment than 

 in its original habitat. Experience with the introduction of various foreign species 

 of animals and plants teaches that the dangers of bringing with them undesirable 

 pests or disease-producing bacteria are almost inevitable. These difficulties and 

 dangers should be carefully considered before any new form is brought in. 



Preparation for Marketing Oysters 



Upon reaching the wharf the oysters carried in a hold or on the deck of an 

 oyster boat are unloaded by means of bucket and hoist, or are delivered to the 

 plant in large steel wheelbarrows. Many oyster houses use elaborate systems of 

 conveyors which take the oysters from the deck, raise them into the upper story, 

 and distribute them to the shucking benches or the packing rooms. Some of the 

 large oyster companies in the northern states carefully wash the mud off the oysters, 

 and then place them for 24 hours in running sea water to which free chlorine gas 

 is added in a concentration sufficient to sterilize the shells. Large concrete tanks, 

 about 3 feet deep, are used for this purpose. They have false bottoms consisting 

 of wooden grids to remove debris and materials discharged by the oysters. It 

 is claimed that washing and chlorination provide additional safeguards against 

 contamination of shellfish and improve their shipping quality. 



In Europe oysters taken from growing grounds are very carefully washed, 

 sorted, and packed for shipment in small baskets or similar containers. Great 

 attention is being paid by French oyster dealers to the cleanliness and good ap- 

 pearance of the shell of the oyster as well as to the flavor of its meat. 



