THE SHELLFISH INDUSTRY
313
and are capable of almost unlimited expansion with the
certainty of producing great quantities of highly nutritious
food.
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It would obviously be of the greatest value if large
supplies of spat oysters could be produced
conditions for- subsequent laying on the commercial beds.
To this end a series of experiments are being carried out
at Conway during the summer—months.
Adult oysters
are placed in the tanks under a series of different Conditions
and the effect of various kinds of foOd on the production
of young and the settling -of,,spat studied. —So far, the
experiments have not been very conclusive but good results
have been obtained by placinglarge amounts of brown
seaweed in the tanks, these produce great numbers of minute
“
spores ”—or_seeds—on which the young oysters readily
feed.
an important etÇect on the spawn—
ing of oysters, the higher the
the more frequent
the changes from male to ._female in the native oyster,
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and so the more frequent the.production of batches of eggs
which are incubated within the shell of the parent for some
days before they swim out into the sea.
At.rstthey are
whitish and theparent is saidto be “white
later, when theyoung begin, to—ieed, theyturn darker and
_
form a greyish mass about the gills
“
black sick ”
parent.
The
Portuguese oyster does not incubate its
young Which develop from the earliest stages in the sea.
..
It has been suggested that they might
be established in
this country by obtaining _ripe adu1ts,.opening.
scattering the reproductive products in.the Water over the
_
beds, where the young
it is thought, settle and grow;
This process
would have to be repeated each year because,
as we have seen, the water is here too cold for this “oyster‘
_
to spawn naturally.
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