the dredge was dropped at the border of the tract, pulled the length of 

 the quarter, and then lifted clear of the bottom. The boat then turned 

 to make another pass across the area. After several drags the dredge was 

 lifted aboard, the catch removed, counted, and measured, and the breakage 

 recorded o 



Dredging continued in each quarter until the same quantity of clams 

 over 60 ram» in length had been obtained as from the corresponding quarter 

 of the bullrake area (Fig. 5). The length of 60 mm. was chosen because 

 it represented about the smallest size caught in any quantity by the 

 dredge. Actually, more clams were removed from the bullraked area than 

 from the dredged area since the rakes caught most of the clams above 

 il5 ram. 



Table 1 shows the amount of clams removed from each quarter by 

 dredging during the experiment. 



Underwater Photography 



Woods Hole Oceanographic Institution took underwater photographs of 

 the bottom after digging had been completed in 19U9. Seven pictures were 

 taken in each quarter of the two test areas and lU in the control. The 

 photographs included a total of 2,520 square feet of the bottom, or 2 l/2 

 percent of the total area of the plot. Unfortunately, due to technical 

 difficulties, many of the pictures were unsatisfactory. Enough were 

 usable, however, to demonstrate that this method can be a practical tool 

 for assessing bottom surface conditions if operational difficulties are 

 overcome. 



Bottom Samples 



We obtained bottom samples with a 2 l/2 cubic foot clamshell bucket 

 each autumn after fishing had been completed (Fig. 6). This bucket 

 sampled an area of ^ square feet to a depth sufficient to remove all of 

 the clams. After the bucket was lifted aboard with the winch, a 

 6" X 6" X 2" subsample was removed and screened through a twelve-^nesh- 

 per-inch plastic screen to recover the tiny clams. The main sample was 

 dumped into a box with a 5/8 inch screen bottom and the mud washed 

 through with a fire pump. The quahaugs were counted and measured and 

 returned to the water outside of the test plot. 



Sampling in 19h9 included 28 grabs in each of the three areas 

 although only 2U of the samples in the control area were usable. The 

 remaining four samples in the control area were incomplete as the bucket 

 apparently landed on edge and came up partially filled. Seven samples 

 were taken in each quarter of each area and were roughly spaced to cover 

 the quarter. Difficulties in establishing exact location of stations 

 because of tide, wind, etc., helped to randomize sampling. 



10 



