190 Report of the Board of Shell Fish Commissioners 



PHYSICAL AND BIOLOGICAL INVESTIGATIONS. 



OBJECT AND SCOPE. 



It is reasonable to expect that barren bottoms which dupli- 

 cate, or which by artificial means can be made to duplicate, the 

 essential physical and biological conditions found to exist on 

 productive natural bars, will produce oysters under private 

 supervision and ownership. 



On the other hand, it is not reasonable to expect barren bot- 

 toms which lack even one of the conditions essential to the 

 growth of oysters to be valuable as an investment for oyster 

 culture. 



The following lines of investigation concerning the physical 

 and biological conditions under which oysters grow naturally 

 in Maryland have therefore been undertaken, in connection with 

 the survey of the natural oyster grounds, with the expectation 

 that the results obtained can be made of practical use to pros- 

 pective planters in selecting barren bottoms for planting pur- 

 poses: 



1. Character of the bottom. 



2. Depth of water. 



3. Velocity of currents. 



4. Density (salts contained) of the water. 



5. Organisms used by oysters as food. 



6. Quantity of oyster food in the water. 



METHODS. 



Character of Bottom. 



The character of the bottom includes its composition and 

 hardness. It is roughly determined at each of the snrvey 

 soundings with the lead line and more accurately at each of the 

 examination stations from the material brought up by the 

 tongs. The findings are recorded in the following terms : Very 



