1298 BULI^ETIN OF THE BUREAU OF FISHERIES. 



Certain enthusiasts, some of whom should know better, have held forth the 

 prospect of a time when the entire available bottom of our bays and sounds 

 would be planted in oysters as densely as are the comparatively small areas now 

 utiUzed. They fail to consider the fact that the natural fertility of the waters 

 imposes some Umit upon the production of oyster food, and that a vast increase 

 in the oyster population, such as their imaginations contemplate, would undoubt- 

 edly exceed the limits which nature has set. 



The microscopic vegetable life of our brackish bays and sounds is probably 

 as abundant as it is capable of becoming under existing conditions. It is depend- 

 ent primarily upon the quantity of certain mineral salts in solution, and is as 

 strictly limited by the conditions as is the crop yield of a given area of land by 

 the available salts in the soil. The soils can have their fertility artificially 

 increased, but though experiments conducted by the author for the Bureau of 

 Fisheries have shown that the same expedient is partially successful for hmited 

 areas of inclosed water, it can never be applied to open waters, as the fertilizer 

 would be speedily carried away. In this connection, however, it is an interesting 

 speculation whether our coastal waters are not to-day richer in fertilizing salts 

 than they have been in the past. The denudation of our forest lands, the 

 erosion due to faulty agriculture, the artificial fertilizers carried away from 

 cultivated fields during periods of heavy rainfall, and the discharge of sewage rich 

 in organic matter have undoubtedly added much to the available fertilizing 

 content of our coastal waters, to the advantage of their microscopic vegetation. 



The question of food supply, its availability, and the quantity required for a 

 given area planted in oysters is one of vital importance to the oyster culturist. 

 Of the total oyster supply of the United States, about five-eighths, valued at 

 over $10,000,000, is produced on planted beds, and the future growth of the 

 industry is dependent upon the increase of the area of private bottoms under 

 culture. With the extension of the planting industry to new localities and the 

 inevitable congestion in places naturally favorable for growing and fattening 

 oysters, the value of definite data upon this subject will be greater in the future 

 than in the past. 



Empirical methods involving actual planting to determine the suitability of 

 a locality are expensive and often wasteful, and operators with small capital are 

 frequently deterred from taking the risk. Even though the work on a small 

 scale may prove successful, an increase to a large commercial basis may overtax 

 the food supply to such an extent as to make the growth of the oysters slow and 

 their fattening impossible. A number of cases of this kind have come to the 

 author's attention, the most noteworthy being in Lynnhaven Bay, where the 

 increase in the area planted, though the quantity per acre is exceedingly small, 

 has made it almost impossible to fatten oysters properly on certain bottoms 

 formerly satisfactory. 



