Effect of Biofouling Control Methods on the Productivity of the Eastern Oyster

Description

In New Brunswick, the farming of eastern oysters (Crassostrea virginica) is mainly carried out using floating Vexar^® bags. This technique allows an easy access to stocks, reduces predation, and promotes growth by maintaining the oysters in relatively warm and phytoplankton-rich surface waters. Nonetheless, floating bags are reputedly vulnerable to fouling organisms. Bags provide a good recruitment substrate for wild mussel larvae (Mytilus edulis). They are also susceptible to other fouling organisms, such as barnacles (Semibalanus balanoides, Balanus balanus, Balanus crenatus), wrinkled rock borers (Hiatella arctica), and wild oysters. Fouling organisms grow rapidly during summer, compete for the same food resources as oysters, and ultimately obstruct water flow. Growers presently mitigate the biofouling problem by exposing bags to air for three days. This "desiccation" approach is quite labor-intensive. An alternate mitigation approach has recently been investigated whereby bags holding oysters are exposed to heat shocks (~ 85℃, 3 sec) with the aim of eliminating fouling organisms without chronically stressing the oysters. The broad objective of this study is to determine whether current and emergent biofouling control methods significantly impact oyster (C. virginica) productivity.

To achieve this goal, we would set up an experiment that allows for direct comparisons between three control methods:

1. desiccation,
2. heat shock followed by an immediate redeployment in seawater, and
3. heat shock followed by a short recovery period.

We propose to investigate the influence of five explanatory factors:

1. desiccation,
2. exposure time to heat,
3. absence/presence of cold-shock,
4. seasonal timing, and
5. size-class.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2008 - 2010

Ecoregion(s)

Atlantic: Gulf of Maine, Scotian Shelf

Principal Investigator(s)

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