FISH AND FISHERIES. 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 larger 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 yéllow, 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 inferior in quality and quantity.’ 
