years, one year of fallowing is useless, particularly when a drill can live for 

 almost a year without food, 



Mistakidis (1951) confirmed Stauber's observation that Urosalpinx does not 

 favor grounds in a poor state of cultivation In his surveys he noted the close 

 association of drills and grounds covered with considerable shell and in a fair 

 state of cultivation . Cole (1951) adds that generally speaking derelict grounds 

 overrun with Crepidula carry few Urosalpinx On the other hand J. R. Nelson 

 (pers, com.) finds on Fireplace, Long Island, that uncultivated bottoms overrun 

 with Crepidula when cleaned with the suction dredge yield far higher drill counts 

 than cultivated areas. 



The fact that the drill is an omnivorous feeder and that dredging of oysters 

 for market does not necessarily denude the bottom of all organisms or of all shells 

 on which new organisms soon set or have set, casts further doubt on temporary 

 abandonment of grounds as a means of drill control . 



Removal of bottom trash 



The practice of removal of old shells and debris from the bottom prior to 

 oyster setting time, as dene by some oyster farmers, and dumping it ashore where 

 drills are killed by exposure is another effective means of combating the drill 

 (Stauber, 1943; Engle, 1940) To counteract the objection that soft bottom in 

 Delaware Bay does not permit this treatment, Stauber recommends the return of 

 the original trash to the bottom after drying ashore . If the trash is not required 

 on the bottom it can be eliminated by Flower's method of disposal. Control by 

 trash removal is a sound one ; and merits wider application The method removes 

 drills and egg cases of all ages, organisms which compete with oysters for the 

 available food, other oyster pests such as Cliona and mud crabs, and the niches 

 which harbor real and/or potential enemies of oysters . 



Ratio of drills to prey 



- Since in general drills approximate a rather uniform distribution over 

 favorable bottom (Mistakidis, 1951), and since young oysters if planted sparsely 

 over such bottom would tend to be more quickly destroyed than oysters planted 

 thickly among the same concentration of drills, F. B. Flower (pers. com.; New 

 Jersey Oyster Research Laboratory) has suggested as a temporary expedient that 

 oyster seed be planted in maximum concentrations In this manner the food re- 

 quirements of the drills present are satisfied by only a partial destruction of the 

 oysters, and overall short range survival of oysters is increased, At first glance 

 this appears like an uneconomical means of control, but if no other is available, 



126 



