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MG-06-01-002
Remote setting and nursing of Crassostrea virginica in bouncing buckets
In Atlantic Canada, and particularly in the province of New Brunswick,
the culture of the American oyster (Crassostrea virginica) is dependent
upon (1) the settlement of wild larvae onto spat collectors (e.g. Chinese
hats) and (2) the subsequent transfer of these spats to grow out sites.
However, this seeding approach is vulnerable not only to broodstock
declines, but also to regulatory transfer restrictions, which can happen
unexpectedly due to health issues (e.g. MSX) or the spread of invasive
species (e.g. tunicates). New transfer restrictions could have devastating
effects, particularly if they apply to reliable spat collection sites such
as Bouctouche Bay.
Remote setting of Pacific oysters (Crassostrea gigas) on the western
coast (Canada and USA) has been researched extensively since the 1970s,
and is currently applied at commercial-scales. The American oyster, on the
other, has received considerably less attention (Supan, no date; Supan and
Wilson 1994). To the best of our knowledge, a single investigation was
conducted on the possibility of applying the remote setting technique to
C. virginica in eastern Canada (Méthé, 1996). Results were encouraging and
clearly demonstrated that the oyster industry in the southern Gulf of St.
Lawrence could benefit from the remote setting technique. The reason is
that the natural spatfall at this northernmost range of the species occurs
in mid-summer, leaving little time for spat growth prior to the onset of
winter. Remotely setting the larvae in early spring considerably extended
the spat grow-out period and obtained large seed oysters (96 to 428%
larger in size compared to naturally-set seed) by the fall of the same
year.
We propose to quantify the setting rates of C. virginica pediveligers
in field bouncing buckets. Méthé (1996) reported setting rates between 6%
and 60% based on a controlled setting environment (tanks); an average
setting rate above 20% would be considered a success for field bouncing
buckets. In terms of null hypothesis testing, our proposed project
essentially aims to compare an innovative remote setting approach (field
bouncing bucket) with a more conventional remote setting approach
(controlled environment). Regarding the nursing component, the goal is to
demonstrate that the newly settled spat contained in the experimental
bouncing buckets can grow into large seeds by the fall of the same year. A
remote setting approach would allow the proponent to extent the summer
growth period by advancing the larvae setting date from late July (typical
in northern NB) to early June for instance. Research has shown that such
an extended summer growth period can produce large (> 25 mm) oyster seeds
by the fall of the same year.
Méthé, D. 1996. Remote setting trials of the American oyster,
Crassostrea virginica. Department of Fisheries and Aquaculture, Bouctouche,
New Brunswick.
Supan, J. E. (no date). Using remote setting to produce seed oysters in
Louisiana and the gulf coastal region. The Louisiana Sea Grant College
Program, Louisiana State University, Baton Rouge, LA.
Supan, J. E. and Wilson, C. A. 1994. The technical feasibility of
commercial hatchery and remote setting operations in Louisiana. Sea Grant
Program, Louisiana State University, Baton Rouge, LA.
Project Start Date: May 12, 2006
Project Completion Date: March 31, 2007
For further information please contact: DFO project leader: Luc Comeau
(ComeauL@dfo-mpo.gc.ca) or
Regional ACRDP Coordinator: Denise Méthé (E-mail:
MetheD@dfo-mpo.gc.ca).
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