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Spawning
tetraploids – Before
spawning, tetraploid males are identified from our
select brood stock lines. Males are sacrificed and
their sperm added to eggs from customer’s normal,
diploid brood stocks. No induction is used. Fertilized
eggs – now 100% 4Cs natural triploid – can
be immediately incubated for culture.
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Hatchability
of 4Cs natural triploid larvae – Under
controlled tests, hatching rate of 4Cs natural triploids
is equally successful as a normal diploid spawn (see
table below), an improvement over hatching rates
of induced triploids which is considerable lower than
4Cs natural triploids.
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Growth, survival of
4Cs natural triploid larvae – D-hinge
larvae (2 days old) of both natural and induced triploids
are larger than diploids. Average daily growth of natural
triploid larvae is almost 50% faster than induced triploids
and diploids, culminating in very large eyed larvae.
4Cs natural triploid eyed larvae are almost 350 microns
compared to about 320 for diploids and induced triploids.
In volume, 4Cs natural triploid larvae are about 1/3
larger.
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4Cs natural triploid
eyed larvae are robust at setting – Because
of their larger size and apparent superior physiological
condition, 4Cs natural triploid larvae are excellent
setters.
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Dependability of the process – Experience
with commercial spawns indicates 162/170 commercial
spawns of 4Cs natural triploids were >95% triploid – 153
of them were 100% triploid. For induced triploid
spawns, 80% triploidy is usually deemed acceptable.
To date, 100% triploids have been produced from tetraploids
in three species of oysters. |
