308 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



course, prevent their submergence in places where the mud was very 

 soft, but as each shell would have to be separately handled it will be 

 found that this method is too exj)ensive to be warranted by the present 

 condition of the oyster business. Another method of utilizing oyster 

 shells as cultch is treated of in connection with the subject of pond 

 culture (pp. 322-330). 



Gravel and pebbles. — This is a form of cultch which is much favored 

 by the planters in some parts of Long Island Sound, its principal 

 advantages being the small size of its constituent particles and its 

 cleanliness. As a rule the pebbles are so small that but few spat fix 

 themselves to each (jilate xviii, fig. 7) and, consequently, there is little or 

 no danger of crowding. Not only do a larger proportion of the young 

 oysters survive their infancy, but they develop into deeper, more regular 

 shapes, are free from bunches, and, consequently, bring a higher price in 

 the markets. Where the«trade in " shell stock " is large the shape of the 

 oysters is a consideration of importance, but where only shucked oys- 

 ters are shipped irregularities in shape are less undesirable. The gravel 

 is more* cleanly than shells, because it is not attacked by the boring 

 sponge, which gives rise to much of the debris found upon the oyster- 

 beds. There is also less liability to the introduction of oyster enemies 

 than when shells are utilized. 



The bottom used for obtaining a "pebble set" must be firmer than 

 that which will suffice for the sowing of shells, the gravel being heavier 

 in proi^ortion to its surface and therefore more liable to sink. It also 

 presents less surface on muddy bottoms, where the pebbles will soon 

 become buried to their equators, and if there is any sedimentation there 

 is left no surface available for the attachment of the fry. Bounded, 

 water- worn pebbles are usually preferred, such offering more surface 

 free from sediment than flat stones. They afford, perhaps, the best form 

 of cultch for use ui)on firm bottoms, when there is sufficient current to 

 prevent the rapid deposit of sediment. It is observed that gravel 

 beaches, when these conditions, obtain, are often the most valuable of 

 natural spatting-grounds. In some places gravelly material dredged 

 from harbors and channels during the improvement of waterways is 

 used to advantage. Crushed stone, averaging about the size of* a wal- 

 nut, is also an excellent collector. Gravel or crushed stone is generally 

 more expensive than shells, costing from 5 to 7 cents per bushel. The 

 custom is to sow from 25 to 30 cubic yards (from 500 to 600 bushels) per 

 acre when used alone, but a smaller quantity if shells are also used. 



Scraj) tiJi, tin cans, etc. — In some places old tin cans and scrap tin of 

 various kinds is found to give good results when used as cultch. It 

 has the advantage of becoming corroded and gradually dissolving in 

 the salt water, thus releasing the young oysters before they begin to 

 crowd one another and allowing them to grow into well- shaped adults. 

 Moreover, as the cultch each year disappears in solution, there is no 

 debris from this source to litter the ground and to cause the expense 

 of culling. It seems that, in the form of old tin cans, this type of cultch 



