riSH AND FISHEEIES. 117 



marsh. The fattening ponds (termed claires) at Marennes and La 

 Tremblade, of which sketches are appended, are at both places formed 

 out of salt marshes, and are in many instances only old disused salterns 

 or salt-pans in which rough salt was made. The number of oysters 

 laid down in claires is proportioned to the time it is intended they should 

 remain there ; for as the food of the oyster is limited, a smaller number 

 will of course fatten more rapidly than a lai'ger number. The average 

 distribution is about two or three to the square foot. The oysters thus 

 fattened are of excellent flavour and quality. 



Mr. Cholmondeley Pennell, Inspector of the English Oyster Fisheries, 

 who was sent by the Board of Trade to inspect and report upon the 

 French modes of oyster culture, says in his report : — ' The fattening 

 pits (claires) are excavated from 1 to 2 feet deep, and are of all shapes 

 and sizes, from 10 to 60 yards square, which latter is the maximum, 

 the usual size being from 40 to 50 yards square. It is in these pits 

 that the celebrated green oysters are fattened. Round the margin of 

 the claires, at Marennes, a trench or channel is excavated a yard or two 

 wide, and an extra foot deep, the object of which is to equalize the 

 temperature when the shallower water becomes too hot or too cold. 

 One portion of the side of each claire is cut down to the depth at which 

 it is wished to keep the water ; this depression communicates with the 

 nearest gully or natural channel, and at spring tides (when only the 

 water in the tides can be changed) the tide, winding its way up the 

 channel, finds ingress and egress. The same channel also serves to carry 

 away the waste water whenever it is wished to lay the pits dry, for 

 which purpose the simple method is adopted of digging a hole in the 

 clay bank, which is readily stopped up again when desired.' 



During the summer months the sea has free ingress and egress to the 

 claires to purify them, and the coating of blackish mud which has 

 collected on the surface during the preceding year is also removed. In 

 August they usually stop up the gaps in the banks, in order that the 

 continued action on the soil and water may produce the greenish creamy 

 scum with which the surface mud of all the claires is covered. Oysters 

 in the claires do not begin to fatten until late in the autumn and winter. 

 A large quantity of oysters will live well in the pits, but they will not 

 fatten if too numerous. There is no doubt that the fewer oysters that 

 are placed in a pit, the more food there will be for each of them and the 

 quicker they will fatten. Wherever these claires have been constructed 

 they have succeeded, and, when once constructed, the labour and expense 

 of working them are small. The claires at Marennes occupy a strip of 

 low-lying clay country on the river Seudre. The soil is marl, that is, a 

 mixture of chalk and clay, and is of various colours — greyish, blue or black, 

 greyish yellow, and in some cases red. The muddy or marly bottoms are 

 most favourable to the growth and fattening of the oyster. Professor 

 Sullivan says : — ' The soil of all places successful as oyster-fattening 

 stations contains more or less of a fine flocculent highly hydrated silty clay, 

 abounding in vegetable and animal matter, derived chiefly from diatomacea, 

 rhizopoda, and other microscopical organisms ; and that the soils of those 

 places which have proved successful as breeding-stations always contains 

 some of it, but not necessarily as much of those which fatten ; and lastly, 

 that in those places which have proved failures, this peculiar kind of mud 

 is either wholly absent or iiaferior in quality and quantity,' 



