his sampling tool, generally overlooks them, By the end of the second summer 

 most of the drills have grown to adult size and the drill population has been aug- 

 mented by another spawning. It is at this time that oystermen usually notice 

 wholesale destruction of young oysters on their grounds and erroneously attribute 

 this to drills which have migrated from contiguous bottoms. Stauber believes 

 that at times migration may play an important role, but that it is secondary to the 

 considerations presented above. 



A dramatic example of the "sudden appearance" of drills on newly planted 

 oyster seed with disastrous consequences was reported to the writer recently by 

 the J. & J. W. Elsworth Co, In the fall of 1951 an 80 acre plot in West Neck, 

 Peconic Bay, Long Islandj was drill dredged by means of the conventional oyster 

 dredge with the 1/4 inch mesh bag The ground was similarly drill dredged in the 

 spring of 1952 and in August of the same year just before 4, 000 bushels of New 

 Jersey oyster spat, varying m diameter from 1/8 to 1/4 inch. were, carefully 

 trucked into Greenport and expeditiously planted on the prepared ground. During 

 the c ourse of the three successive drill dredgings a marked decrease in the number 

 of drills was reported . But in two weeks most of the newly planted spat had been 

 drilled, and in three weeks the entire planting was a commercial loss'. The majority 

 of drill holes in the destroyed spat were minute, and a minimum of two to four drills , 

 mostly very small in size were counted per cultch shell. Although it is reason- 

 able to assume that the majority of the larger drills were removed from this ground 

 during the successive drill dredgings, there is no assurance that many of the minute 

 drills were not washed back onto the bottom through the 1/4 inch mesh bag of the 

 dredge; the reported diminutive size of the drills and their perforations support 

 ■ins contention. In the short span of three weeks time during which the spat were 

 destroyed it is inconceivable that, even though attracted by the young oysters, 

 enough of these small drills could have migrated onto the bed, or been transported 

 there on drifting debris or on the back of larger animals, to cause the damage re- 

 ported. The very strong suggestion in this instance is that the spjt were destroyed 

 principally by young drills already on the ground at the time of planting 



F. B. Flower and associates, New Jersey Oyster Research Laboratory 

 (pei s com ,), have been making observations in Delaware Bay in cooperation with 

 the Claude Jelferies & Sons suction dredge the "Luther Bateman" which further 

 confirm 'he fact that significant numbers of drills may be washed through the dredge 

 screen. Material drawn off the bottom by the dredge is flushed onto two shaker 

 sc re< as, a one inch mesh and a 1/4 x 3 inch mesh screen. Larger drills passing 

 through the one inch screen and held on the 1/2 x 3 inch screen may be counted 

 withoul too much difficulty; the smaller drills passing through the finer screen are 

 much more difficult to find At first the material passing through the finer screen 

 was examined in wet 1/2 bushel quantities, but this method was time consuming 



100 



