318 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



front edge to the upper rear edge of the frame. Attached to the 

 lower front bar is a broad blade of iron or steel, inclined somewhat 

 downward and forward from the plane of the bottom of the box. The 

 whole is attached to a dredge frame, to which the chain used in 

 dragging is made fast. (See cuts 4 and 5.) 



When this appliance is dragged over the bottom the oysters and other 

 inhabitants of the beds, together with shells and debris of all kinds, 

 are lifted from their resting-places by the blade and deposited upon the 

 inclined screen or apron. The motion of the trap and the pressure 

 exerted by the accumulating material in front gradually pass the mass 

 backward across the screen, the smaller particles, drills, etc., sifting 

 into the box, while the oysters, being too large to pass through, finally 

 fall over the edge behind. 



By this means the varied material on the beds undergoes a process 

 of screening, the oysters being automatically returned to the bottom, 

 while a large part of the debris is held and brought to the surface. 

 That the device will accomplish this has been demonstrated, but whether 

 the drill can be successfully fought by this means has still to be shown, 

 although the prospects are favorable. 



PROTECTION FROM WINKLES. 



The conchs or winkles have never been a serious menace to our 

 oyster-beds. Their small numbers and large size and the large size of 

 their egg cases make it possible to successfully fight them by destroy- 

 ing all winkles and egg cases brought ui) in the process of dredging or 

 ton gin g. 



PROTECTION FROM SPONGES, HYDROIDS, MUSSELS, ETC. 



The growth of sponges, hydroids, etc., when so rank as to threaten 

 the welfare of the oysters, may be kept down by working over the beds 

 with the oyster dredge and culling out the debris. A thorough cleaning 

 up of the ground before planting and the use of clean seed and cultch 

 go far toward the prevention of trouble from this source. 



PROTECTION FROM STRONG VEGETABLE GROWTHS. 



In places where eelgrass {Zostera), etc., grow so rapidly as to cause 

 stagnation of the water and suffocation of the oysters some means must 

 be adopted for its removal. Sometimes it may be removed with an ordi- 

 nary scythe at low water. A grower in New Jersey has invented for 

 this purpose what has been termed an "aquatic mowing machine." 



It is described as follows : 



Eelgrass grows abundantly in some parts of the Navesink River and, as in other 

 localities where it is found, acquires in due time full possession of the areas where 

 it grows, rendering them useless for oyster-culture. In combating this enemy of 

 the oyster-planting industry, Mr. Charles T. Allen, of the firm of Snyder & Allen, 

 Oceanic, N. J., has achieved a degree of success heretofore unequaled. After 

 expending much fruitless labor in eft'orts to mow the eelgrass with a scythe, a method 

 which proved impracticable because the water was sometimes too deep and also on 



