Figure 8. — Drawing of a 48-inch hydraulic clam dredge built for clam survey work aboard the National Marine 

 Fisheries Service research vessels Delaware and Delaware II. 



carries the material dredged from the bottom 

 with it. When fully developed, this system will 

 offer the possibility of continuous dredo-ing- 

 without interruption and loss of fishing time 

 for hauling, em])tying, and resetting the dredge. 

 In addition, the catch can be constantly mon- 

 itored, and small beds can be effectively fished. 

 After preliminary investigation of the feas- 

 ibility of this method. Snow Canning Comimny 

 of Pine Point, Maine, began to assemble the 

 needed gear and equipment for building an air- 

 lift system on their vessel Gail Borden. After 

 building and pretesting component units of 

 the system, a working model was given lim- 

 ited fishing tests during the spring and sum- 

 mer of 1964. Many "bugs" were found, and 

 further effoii for modifying the system to cor- 

 rect deficiencies continued. Near the middle 

 of 1965, the redesigned unit was ready for 



further testing (Figs. 9 and 10). While some 

 minor deficiencies remained, test results were 

 encouraging enough to warrant the develop- 

 ment of a complete system for future clam 

 harvesting. 



In addition to these developments, submers- 

 ible pumping systems have been developed to 

 replace the older type vessel-mounted pumping 

 systems used on all the commercial clam boats 

 today. Such a system has an electrically driven 

 submersible i)um]) (of suflicient power and 

 rating) (Fig. 11) mounted on the forward end 

 of the clam dredge. The discharge end of the 

 pump is connected directly to the dredge man- 

 ifold (Fig. 12). Electrical energy is supplied 

 to the pump from a vessel-mounted generator 

 feeding ]3ower through a watertight ]30wer 

 cable which is stored on a deck-mounted hy- 

 draulically-driven reel. The main advantage 



