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Quantifying the effect of winter siltation/burial on Crassostrea virginica 's health



Oysters on the sea floor in an eelgrass bed.
Photo: Luc Comeau (DFO)

In commercial shellfish aquaculture operations in the Gulf of St. Lawrence estuaries, mesh bags containing cultivated oysters (Crassostrea virginica) are lowered onto the seabed in October – November and recovered five to six months later, after the thick winter ice cover breaks up and moves offshore. Oyster farmers periodically report mortalities when bags are recovered from the seabed in the spring, with oysters exhibiting dark gaping shells containing black anoxic sediments and traces of still decomposing tissues. It is suspected that oysters are vulnerable to sedimentation and burial during the winter period (due to low oxygen levels or silt clogging the gill apparatus). This project will explore the cause-effect relationship of winter siltation/burial on oyster health and productivity, as well as investigate potential mitigation measures. A better understanding of the consequences of winter burial on oyster biology and physiology may result in improved management options. Additionally, the results of this research will provide the information required to determine whether oysters can be overwintered successfully on soft-bottom sediments. This would allow for oysters to be overwintered in deeper channel waters (greater than 4 m) where eelgrass (a species declared to be ecologically significant in 2009) cannot grow. Moving the overwintering bags from on top of eelgrass beds to deeper channels will reduce the potential for damage to eelgrass communities.

This project supports the optimal fish health management objective of the Aquaculture Collaborative Research and Development Program (ACRDP) and pertains to the 2014-15 national ACRDP priority of maintaining healthy populations through the proactive development of approaches to manage health issues that may arise for cultured shellfish species.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)


2014 - 2016


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

Principal Investigator(s)

Luc Comeau

Collaborative Partner(s)

L'Étang Ruisseau Bar Ltd.

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