§38 | REPORT OF COMMISSIONER OF FISH AND FISHERIES. [14] © 
flood-gate, at the first great spring-tide in order that the claire may 
remain full; and, thanks to this measure of foresight, the oysters are 
placed at a depth where the causes of mortality from which they seek 
to preserve them cannot so easily reach them. The culturists who 
are not sufficiently vigilant in this respect soon become the victims of 
their carelessuess. In 1820, the precautions of which I speak not having 
been taken in time, the colds of the first days of January became sud- 
denly so severe that the waters of these claires and the oysters them- 
selves, not having sufficient depth of water, were frozen so that it 
was impossible to remedy the disaster. The entire crop perished in 
one day. 
If the waves of the sea did not bring in upon the bottoms of the clatres 
a mass of slime, the deposition of which is favored by the stagnation of 
the waters, there would be no more to do, as I have already said, but to 
leave the oysters in repose on this well-provided bottom, where abun- 
dant nourishment is secured for them. They would be brought to 
perfection under the influence of this clear water; quickly becoming 
fat, large, and green, without receiving any other care; but the slime, 
progressively accumulating, threatens to destroy them, and will infal- 
libly become a deadly poison to them, if they are not quickly withdrawn 
from its influence ; and the slime is all the more fatal as it attacks every 
individual at the same time. Industry has succeeded in protecting the 
oysters from these unhealthy sediments by transporting the whole pop- 
ulation from a claire in operation to a claive at rest, and by renewing 
the operation whenever necessary, until the maturity of the crop. To 
provide for all the needs of the experiment, it is necessary to have at 
their disposal a greater number of reservoirs than is actually necessary 
to lodge the oysters while they are perfecting. There are in the environs 
of Marennes speculators who possess 20 or 30 of these reservoirs, of 
which 8 or 10 are always at rest, in order that they may put them to 
use as soon as a claire becomes slimy and obliges them to transfer the 
crops to a vacant one. By the aid of this transfer, several times re- 
peated, they preserve their crops and give them, at the end of a certain 
time, qualities which those do not possess, in the same degree, which 
have received less prolonged care. 
It becomes necessary to repair the claires at the period of the equinoctia] 
spring-tides, which are the strongest and the most injurious on account 
of the great quantity of slimy matter which they bring; but these periods 
are not the only times when a change must be made. It may happen 
that the earthy deposits will necessitate a removal at other seasons; 
generally it is done only once a year. The producers who have not at 
their disposal a sufficient number of claires are content to cleanse their 
oysters and replace them on the same bottom, thus carrying on their 
business under very unfavorable conditions, but nevertheless profitably. 
It requires a sojourn of two years in the claires for oysters twelve or 
fifteen months old at the time when they are placed there to attain a 
