permitted on natural beds, a tonger nnay catch 

 sometimes 25 to 30 bushels a day. 



Dredges vary in methods of their operation 

 and in their holding capacity. In some areas, 

 such as the public grounds of Chesapeake Bay 

 and Connecticut, no powered craft can be used 

 and only hand-operated dredges are permitted 

 (fig. 21). Therefore, these dredges are com- 

 paratively small, having a capacity of only 

 about 1 or 2 bushels. On private grounds, how- 

 ever, large machine-hoisted dredges are used 

 (figs. 22 and 23). The capacity of these dredges 

 may exceed 20 bushels. Normally, a typical 

 oyster dredging boat of Long Island Sound is 

 equipped with two dredges, one on each side 

 (fig. 24). In the past, some of the largest 

 vessels, equipped with three dredges on each 

 side, were capable of harvesting at the rate of 

 1,400 bushels per hour. 



After World War II, considerable progress 

 was made in mechanizing and improving 

 methods of oyster harvesting. One step in 

 this direction was constructing a suction 

 dredge, which works on the principle of a 

 vacuum cleaner (fig. 25). Suction is produced 

 by a powerful jet of water, and the power of 

 the suction carries oysters and other mate- 



rials from the bottom to the conveyor located 

 on deck of the dredge boat. While moving on 

 the conveyor, the material is examined and 

 handled as necessary, including sorting of 

 oysters according to size. 



In addition to harvesting oysters, suction 

 dredges are extremely efficient in clearing 

 oyster bottoms of various enemies, such as 

 starfish, mussels, crabs, Crepidula , and some- 

 times drills. A larger suction dredge vessel 

 of this type has been in almost continuous 

 operation in Long Island Sound since 1948. It 

 is about 100 feet long, 30 feet wide, and draws 

 8 feet of water. Its capacity is 10,000 bushels. 

 On the basis of its past performance, it is 

 regarded as an extremely efficient and ver- 

 satile device. 



The escalator or, as it is sometimes called, 

 scooper-type of harvester also has been de- 

 veloped since the war and is used m several 

 oyster-producing areas. This type of harvester 

 is most effective in relatively shallow water. 

 The dredge of a scooper-type harvester has 

 a rakelike appearance and is equipped with 

 steel teeth. During operation it is lowered to 

 the bottom where it rests on special runners 

 on each side which prevent the dredge fronn 



Figure 21. — Sailboat dredging oysters on public beds. 

 30 



