[43] OYSTER-CULTURE UPON SHORES OF BRITISH CHANNEL. 715 



Ile des Oiseaux (Parcs of Crastorbe). — The He des Oiseaux is 

 the largest of the crossats of the bay, and the planters regard it as the 

 most favorable ground for the cnltivation of the oyster. The Oyster- 

 Cultural Society possesses there 11 hectares of claires. The bottom of 

 these claires has been transformed before being brought into use. It 

 originally consisted of mud several meters in thickness, and of so little 

 consistency that one could scarcely pass over it even by using very large 

 padns. A consolidation of it was effected in the following manner: At 

 first there was spread over the space a layer of shell and sand, suth as 

 is common in the Bay of Arcachon. Upon tliis layer, the thickness of 

 which varied according to the greater or less consistency of the mud, 

 there was spread another layer of pebbles as large as nuts, the material 

 being brought from the quarries of Gazinet, near Bordeaux. These 

 parcs being exposed to strong currents, it was necessary to surround 

 them with pickets. They are emptied by a gate, which also serves to 

 retain the water at low tide, when they would otherwise be left bare. 

 In order to avoid the damage that the rising tide might cause, the gate 

 is left shut until the sea has already filled the claire half full by filter- 

 ing through the sides. 



This portion of the establishment of the Oyster-Cultural Society is 

 devoted to the fattening of the oyster and its preparation for shipment. 



No oysters are marketed from the lie des Oiseaux which have not at- 

 tained a diameter of G centimeters or more, and although they grow 

 deep and round there, they increase in diameter only about 2 centi- 

 meters a year. 



The oysters cultivated at Crastorbe are obtained either from the 

 natural bottom or from the tile collectors. A few of them have spent 

 a portion of their time at La Tremblade ; but in general their early 

 growth is effected at Lahillon. I will add that the borders of the parcs 

 of Crastorbe have retained the condition of natural oyster grounds. 



MM. Venot & Co. cultivate both the native oyster and that obtained 

 from tiles. Reproduction upon collectors is common everywhere at 

 Lahillon and in the parcs of the Jacquets. Tiles alone are employed and 

 are placed in position sometime in May or June, according to the mean 

 temperature of the spring, which, moreover, regulates the time of the 

 emission of the spawn. They are removed about the month of I^ovem- 

 ber. The detaching of the shells from the tiles is performed upon [the 

 vessel] Le Travailleur, generally before winter approaches. The young 

 are placed in frames soon after, upon which they pass there the cold 

 season and repair the damages that the detroquage has caused to the 

 shell. When transferred in tlie spring to the parcs of Lahillon they 

 have become sufficiently strong to defy their enemies. 



The Oyster Cultural Union the present year immersed 110,000 tiles, 

 and its pares contain about 30,000,000 of oysters. Sixty persons are 



