NATURAL OYSTER BEDS OF DELAWARE. 5 



already described by others more definite in respect to the desired 

 particulars. Whenever, in the opinion of the officer in charge of the 

 sounding boat, such information was required, a numbered buoy 

 was dropped, the time and number being entered in the sounding 

 book. Another launch, following the sounding boat, anchored 

 alongside the buoy, and a quantity of the oysters and shells were 

 tonged up, separated by sizes, and counted. 



This boat at each station made a known number of "grabs" 

 with the oyster tongs, exercising care to clean the bottom of oysters 

 as thoroughly as possible. at each grab. In a given depth of water 

 and using the same boat and tongs, an oysterman will cover prac- 

 tically the same area of the bottom at each grab, but, other factors 

 remaining the same, the area of the grab will decrease with an increase 

 in the depth. 



Careful measurements were made and tabulated showing the 

 area per grab covered by the tonger employed on the work at each 

 foot of depth of water and for each pair of tongs and boat used. 

 With these data, and knowing the number of " grabs," the number 

 of oysters of each size per square yard of bottom was readily obtain- 

 able by simple calculation. The following example will illustrate 

 the data obtained and the form of the record : 



Department of Commerce and Labor, 

 bureau of fisheries. 



field record of examinations of oyster beds. 



General locality, Delaware Bay, Delaware. 

 Local name of oyster ground, Over-the'-Bar. 

 Date, July 9, 1910. Time, 8.50 a. m. 

 Angle, B 146-B 147. Buoy No. 6. 

 Depth, 18 feet. Bottom, soft. 

 Condition of water, clear. 

 Density, 1.008. Temperature, 25° C. 



Current, Stage of tide, one hour flood. 



Tongman, M. A. Du [field. 



No grabs made, 8. Tongs, 20 feet. 



Total area covered, 2.5 sq. yds. 



No ovsters taken I 1 in -> 1S ' 1 in -~ S '" ' ' 129 ' 

 Wo oysters taken ^ . n _ 4 .^ 5g 4 {n ^ n 



Quantity shells, 14. 



I Spat per square yard, 5.2. 

 Culls per square yard, 51.6. 

 Counts per square yard, 28.0. 



This furnishes an exact statement of the condition of the bed at a 

 spot which can be platted on the chart with error in position of not 

 more than a few yards. From the data obtained a close estimate may 

 be formed of the number of bushels of oysters and shells per acre in 

 the vicinity of the examination and, by multiplying the observations, 

 for the bed as a whole. In the course of the survey 590 observations 

 were made at various places, principally on the natural rocks, but 

 some on the barren bottoms also. 



