REPORT OF THE COMMISSIONER OF FISHERIES. 83 



found, too, that there was some danger in the application of lime, a 

 variation in the methods previously used having resulted in the 

 destruction of a large proportion of the diatoms. At the close of the 

 fiscal year, experiments were being conducted with extremely attenu- 

 .ated solutions of copper sulphate, after the method of water purifica- 

 tion developed and recommended by the Department of Agriculture. 



A second difficulty was the gradual freshening of the water in the 

 claire during periods of excessive rainfall. To overcome this, a pro- 

 peller pump was installed to maintain constant fullness of the pond by 

 pumping water from the bay to replace that lost by evaporation, the 

 pump being driven by the same engine which operated the propeller 

 for maintaining currents. The results were entirely satisfactory. 



In general it may be stated that the feasibility of fattening oysters 

 by this method has been amply demonstrated, but owing to the many 

 unforseen difficulties and delays encountered, it has not been possible 

 to operate the claire at its full capacity, and the commerci^al possibili- 

 ties of the system have not yet been developed. 



Exjperhnents on the North Carolina coast. — The experiments and 

 investigations in oyster planting and oyster culture begun on the North 

 Carolina coast in 1902, in collaboration with the geological and nat- 

 ural history survey of North Carolina, have been continued by the 

 Bureau through the Beaufort laboratory. The work has been con- 

 ducted in Pamlico Sound and Newport and North rivers, but in the 

 past fiscal year was confined to Pamlico Sound. 



The object of these experiments is primarily to ascertain to what 

 extent and with what profit the great areas in this region now barren 

 of oysters may be made productive, whether the absence of oysters in 

 a special region is due to other causes than the lack of cultch, and what 

 method of planting- is best suited to the particular combination of con- 

 ditions (bottom, depth, abundance of spat, salinity, food, etc.) prevail- 

 ing in a particular locality. 



Private planting seems to be on the increase; while yet verj^ limited, 

 it is apparently more common and more profitable than it was a few 

 years ago. In at least one region (Portsmouth) such planting has 

 already proved to be cramped by the scarcity of "seed." Large areas 

 convenient to such places, but not adapted to yield a market product, 

 might be utilized b}^ private persons or by the state for growing seed 

 oysters. It is also to be determined whether the present natural beds 

 ma}'^ be artificially enlarged. 



Thirty plants were made during 1904, there being now a total of 35 

 plants in 13 localities. Some of these plants have been made not with 

 the immediate object of creating small oyster rocks, but to answer cer- 

 tain definite questions; for instance, before making extensive plants 

 in doubtful places it is advisable to ascertain whether spat will catch 

 in such an area, and to what extent sanding up or sinking in the mud 



