44 OYSTER CULTURE EXPERIMENTS IN LOUISIANA. 



and at various places in Terrebonne Parish, this difficulty has become 

 a serious impediment to oyster culture. 



In some cases the trouble is undoubtedly due to the overcrowding 

 of oysters on the planted beds or to the planting of such extensive 

 areas that the total oyster population of the region affected is in ex- 

 cess of the number for which the waters are able to furnish an ample 

 food supply. In any given body of water, under fixed conditions of 

 drainage and tidal flow, there is probably a more or less fixed limit 

 to the production of the minute plants on which oysters feed, and a 

 correlated limit to the number of oysters that can be produced for 

 the market. Where this limit is exceeded either by planting densely 

 over a small area or more sparsely over an extensive one, especially 

 in an inclosed body of water, the result is manifested in the poor con- 

 dition of the product. This is not a theory, but a demonstrated fact, 

 analogous to overgrazing of cattle on pasture lands, and must be 

 given consideration by the successful oyster culturist. The same 

 condition is induced by a heavy growth of mussels and other organ- 

 isms whose food is the same as the oysters. 



There are, however, other cases of failure of oysters to fatten which 

 are not so well understood. Regions formerly favorable sometimes 

 entirely cease to produce marketable oysters, even where there has 

 occurred no material change in the density and distribution of the 

 oyster population. In such instances it often happens that there has 

 been some coincident sudden or gradual change in the drainage or in 

 the tidal flows. 



Something of this nature seems to have occurred in the vicinity of 

 Bay Adam, where practically no fat oysters are now produced, 

 though we were informed that in former years good oysters were 

 grown regularly. Coincidently with this change in conditions, the 

 rice fields draining into the bay went out of production. It is the 

 opinion of some of the oyster planters that the two occurrences were 

 causally related, and the authors concur as to the probable truth of 

 this explanation. Undoubtedly the drainage from the rice fields 

 carried with it considerable quantities of the fertilizing salts required 

 for the production of the microscopic plant food of the oyster, and 

 since these enriching materials have been largely or entirely cut off the 

 waters have become less fertile and productive. It has been proposed 

 to correct this deficiency in several places by conducting fresh water 

 to the oyster grounds from the Mississippi River through siphons 

 such as were used in the irrigation of the rice fields. Wliether or not 

 this measure would afford effective relief is a matter of some doubt. 

 It can hardly be questioned that much of the fertility of the waters 

 formerly came from the organic and mineral matter carried from 

 the rice fields themselves, and it is doubtful whether the river water 

 itself carries organic matter in sufficient quantity to afford material 



