OYSTER CULTURE EXPERIMENTS IN LOUISIANA. 19 



were repeated on two adjoining areas of the same size, the quan- 

 tity of material in these cases being reduced to 30 and 20 bushels, 

 respectively. 



During 1907 the plants with oyster shells were made April 16, 

 May 21, and June 25, and a single plant of clam shells was deposited 

 on May 21. Thirty bushels of oyster shells were spread, each, on 

 July 26, August 26, September 26, and October 29. 



In 1908 oyster shells were deposited broadcast and in piles on April 

 20 and May 27. There were in all 25 plantings, and on every one ex- 

 cepting that of October 29, 1908, a set of spat was secured before the 

 end of the year in which the shells were deposited. The plants of 

 April, May, and June, 1908, remained barren during the period in 

 which the crevasse water was pouring over the beds, but after this 

 was stopped and the water grew more salt a small set appeared on 

 these shells, a larger one being prevented probably by the silt de- 

 posited by the flood waters. 



The results demonstrated that under usual conditions a strike of 

 young o3'sters is almost certain to occur upon shells or other cultch 

 dej^osited between April. 1 and October 1, a period of six months. 

 Even in the case of the October plant the shells, notwithstanding 

 their long exposure, were still in condition to receive a small set in 

 the following spring. 



The proportion of shells to which young oysters attached within 

 a month after they were planted varied from 40 to 90 per cent, those 

 planted in May, June, and July being usually most effective as spat 

 collectors. The shells spread broadcast were more efficacious than 

 those deposited in piles, though the latter usually became leveled by 

 the waves after the lapse of a few months. The clam shells were 

 less effective than oyster shells, probably in part because, being 

 lighter and smaller, many of them were carried by currents and 

 waves away from the squares on which they were planted. From 

 1 to 5 young oysters were found attached to the oyster shells at the 

 end of one year, the average being about 2 or 3 to each. At a later 

 date the shells became more or less disintegrated and broken, result- 

 ing in a natural culling which freed the oysters from their attach- 

 ment. After the lapse of a year most of the clam shells bore but 

 single oysters, though there were occasionally two attached. 



The experiments indicate that from 400 to 600 bushels of shells 

 per acre can be advantageously planted on firm or moderately firnj 

 bottom. On soft bottom more should be used, as some will be- 

 come buried in the mud. Later, when there are more breeding 

 oysters in the vicinity and the waters become more thoroughly 

 charged with fry, the set on individual shells will become heavier 

 and the quantity of material planted should be reduced to prevent 

 overcrowding. If the set should become very heavy clam shells or 



