Floating Oyster Gear in New Brunswick: Testing the Bird-Deterring Effectiveness of Various Gear Designs

Description

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.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2006 to 2008

Ecoregion(s)

Atlantic: Gulf of St. Lawrence, St. Lawrence Estuary

Principal Investigator(s)

Luc Comeau
Email: Luc.Comeau@dfo-mpo.gc.ca