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MG-06-04-003
Floating Oyster Gear in New Brunswick: Testing the Bird-Deterring
Effectiveness of Various Gear Designs
In New Brunswick, American oyster (Crassostrea virginica) aquaculture
is mainly carried out using floating Vexar® bags. This technique keeps the
filter-feeding animals in relatively warm and phytoplankton-rich surface
waters. However, during routine sampling in September 2004, the Canadian
Food Inspection Agency (CFIA) noticed the presence of bird fecal matter
deposited on a number of floating bags containing market-size oysters, a
situation that was deemed to be an unacceptable health and safety risk.
Some oyster samples were found to exceed the standard for fecal coliforms,
and both the CFIA and Environment Canada recommended that all oyster
suspended culture sites situated in the waters of Eastern New Brunswick be
immediately closed to harvesting. DFO proceeded with a closure order,
which resulted in the near total shut down of all oyster production and
marketing activities involving some 150 aquaculture sites.
As of 2006, all oysters grown in suspension are considered at high risk
of being contaminated with fecal coliforms. For that reason, suspended
culture gear of all types can no longer be used for the mandatory
depuration procedure (Prior to their marketing, all shellfish must undergo
a depuration procedure which typically involves moving the animals from
their culture site to an area open to shellfish harvesting, where they
remain completely immerged for a period of either 14 days (with subsequent
testing) or 30 days (without testing). This policy entails a new husbandry
step which is quite labor intensive, i.e. that the two side-floaters be
removed from the Vexar bags for a complete immersion of the bag at the
depuration site. Thus the bulk of the industry is currently growing
oysters using floating gear which must be converted into non-floating gear
a few weeks prior to the marketing of oysters.
The industry is considering in proceeding with a low-cost modification
which would convert the floating gear into anti-roosting platforms. While
this option is appealing and will be investigated as part of the proposed
study, it is possible that some individuals will ultimately adapt and
roost on the modified-gear, albeit the numbers would be low compared to
the current floating gear structures. The industry is proposing two
research objectives: (1) evaluate the bird-deterring efficiency of four
experimental floating gear types, and (2 evaluate whether the birds will
use the deterring gear when no other option is made available to them.
Project Start Date: August 10, 2006
Project Completion Date: March 31, 2008
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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