6 NATURAL OYSTER BEDS OF DELAWARE. 



In estimating the relative productiveness of the bottoms it appeared 

 advisable to depart from the methods employed in the James River 

 survey on account of the difference in the conditions under which the 

 industry is prosecuted. Where tongs are used exclusively, a bed 

 with a given quantity of oysters lying in shoal water is more valuable, 

 commercially, than one with the same quantity of oysters in deep 

 water, owing to the fact that the labor of the tonger is more efficient 

 on the former. As has been pointed out, the area covered by a 

 "grab" decreases with the depth, other factors being the same, and 

 moreover the deeper the water the greater is the labor involved in 

 making the grab and the smaller is the number of grabs which can be 

 made in a given time. 



In Delaware Bay, while there is a certain amount of tonging during 

 the fall and at such times as the weather will permit in winter and 

 early spring, the most important and productive fishing is by means 

 of dredges, the use of which is permitted from April 15 to June 30, 

 inclusive. In dredging, the effects of varying depths of water, within 

 reasonable limits, are practically negligible so far as the catch is con- 

 cerned. The time required for winding in from deep water is greater 

 than from shallow water, but as the dredge is approximately equally 

 efficient whatever the depth, and as the difference in the time required 

 in winding is small as compared with the period during which the 

 dredge is on the bottom, the factor of depth, so important in tonging, 

 is practically inconsiderable, 

 i The classification adopted in this report is as follows: 



Depleted bottom Less than 25 bushels per acre. 



Very scattering growth __* Between 25 and 75 bushels per acre. 



Scattering growth Between 75 and 150 bushels per acre. 



Dense growth Over 150 bushels per acre. 



As the region is important for the production of seed rather than 

 market oysters, all sizes are included in the estimates of the density 

 of oyster growth, but all loose shells and other debris commonly 

 dredged are excluded. "Depleted bottom" is not necessarily that 

 which was formerly productive but now practically barren, but is 

 merely an expression of the present impoverishment of the bed without 

 respect to its past. In some cases it may be a formerly barren area 

 slowly coming into productiveness. 



The bottom rated as bearing a "very scattering growth" is the 

 least productive bottom capable of furnishing a livelihood to the 

 dredgers. 



In the course of the survey 16,435 acres, or over 25 square miles, 

 were explored with sounding lines and chains. Of this area 2,144 

 acres were found to be included in oyster beds of varying degrees of 

 productiveness. In the survey the chain was dragged over 124 miles 

 of the bottom, soundings were made at 5,772 places, and the position 

 of the boat was instrumentally determined at 819 points. 



