310 REPORT OP COMMISSIONER OF FISH AND FISHERIES 



Apparently this method has never been used in our waters, but where 

 it is necessary to use oyster shells for cultch it might perhaps be 

 applied to advantage. In this case the fry could not be economically 

 detached by hand, but there is little doubt that the growing oysters 

 would automatically liberate themselves. The coating used in France 

 consists of a mixture of sea water, lime, and sand, or hydraulic cement, 

 "stirred to the consistency of thick cream." Various formulae are used 

 by different culturists, three of them being as follows: 



1. One part quicklime, 3 parts fine sand. 



2. One part quicklime, 1 part line gray mud. 



3. First a light coating of quicklime, and, after drying, a coat of 

 hydraulic cement. 



The coating should be such as not to readily wash off, yet suihciently 

 brittle to flake under the mutual pressure exerted between the growing- 

 oysters, and about ^-inch in thickness. 



For convenience in coating, Dr. Eyder recommended that the shells 

 be placed in a wire basket and dij^ped into the cement vat, the mixture 

 being then allowed to set before the shells are used. 



GENERAL CONSIDERATIONS ON SPAT- COLLECTING. 



Whatever may be the character of the cultch, it should invariably 

 be clean and without any surface deposits which might tend to prevent 

 the fixation of the spat. For the same reason the cultch should not 

 be placed upon the beds long before the season for setting. 



In almost any body of water, except where the currents are swift, 

 there is more or less sedimentation, and it is obvious that the shorter 

 the time that a body is exposed to such action the thinner must be the 

 deposit. If the cultch is placed in the water long before it is needed 

 the deposit of sediment is often so thick as to stifle the young oyster, 

 but on the other hand if the time be well chosen a practically clean 

 surface is presented and a good set is more likely to reward the planter. 

 The latter's aim should, therefore, be to determine as nearly as possible 

 the time when the maximum amount of spawn falls, and to so regulate 

 his operations that his cultch is laid down but a few days before. Tbe 

 time will vary somewhat Avith the locality, and if there is no local expe- 

 rience to guide the beginner he may be compelled to experiment a little 

 to find the most favorable time for exposing his collectors. It should 

 be remembered that while the spawning season in any given locality 

 extends over a number of months, the majority of the oysters spawn 

 within a more circumscribed period, usually about midway between the 

 two extremes. 



If the time at which the collectors are exposed be well chosen, and 

 the location of the beds properly selected, the planter may or may not 

 obtain a good set. Sometimes one bed will show a strong set, while its 

 neighbor appears to have been entirely passed over by the fry. Often 

 the cultch in one part of the bed is thickly incrnsted with spat, while 

 another i)ortiou, apparently equally well located and upon which an 



