MG-03-01-003
Development of a broodstock genetic program for the European Oyster (Ostrea
edulis) in Nova Scotia
The European oyster (Ostrea edulis) was introduced to the Nova Scotia
aquaculture industry 30 years ago. The stocks were imported from
naturalized populations in Maine, whose ancestors originated from the
Netherlands. In past years, Nova Scotian hatcheries have successfully
produced Ostrea edulis spat, but in 2001 and 2002 the two remaining
hatcheries in the province suffered 100% larval mortality. One of the
factors that may have contributed to the collapse is a suspected loss of
genetic diversity due to the limited number of individuals used to
establish the Maritimes stocks, and the inevitable subsequent inbreeding
during propagation of these populations. Using microsatellites, we found
that some genetic erosion has occurred in the Maritime populations, with
the largest loss of alleles found in the hatchery stocks. In spite of this
loss, genetic diversity and heterozygosity in the Maritimes populations
are still relatively high.
While the impact of inbreeding and heterosis on performance (survival,
growth, settlement success) could not be evaluated in this project due to
mortalities, we found no evidence of selfing (self-fertilization) but did
find evidence that mass spawning is dominated by a few individuals.
The impact of grading spat was also evaluated. Smaller oysters
(normally discarded as “runts”) showed increased growth rate (% mass and
size) when competition from larger oysters was removed and when density
was lower.
Recommendations for broodstock management of Ostrea edulis and the
direction of future studies of this species are summarised at the end of
this report.
Project Start Date: April 15, 2003
Project Completion Date: September 3, 2004
For more information, contact: DFO Project Leader B. Vercaemer
(E-mail:
VercaemerB@mar.dfo-mpo.gc.ca) or Regional ACRDP Coordinator Denise
Méthé (E-mail: MetheD@dfo-mpo.gc.ca
)
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