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Investigating Polydora outbreak in New Brunswick off-bottom cultured oysters



Known simply as a "mudworm" or "blisterworm", Polydora websteri has the ability to bore into the shells of live and dead shellfish. Commonly found in intertidal and subtidal areas in Atlantic Canada, its presence among New Brunswick oyster populations has normally been minor and usually of low intensity with burrows containing little or no mud. However, there have been sporadic increases of infestation rates observed in off-bottom (or suspension) oyster growing sites in New Brunswick. Some reports have indicated that heavy infestations can result in low meat quality, abscesses, alteration of growth patterns, and weakened shells (increasing predator susceptibility). This unusual increase could ultimately lead to serious impacts on oyster populations and result in economic losses for the aquaculture industry. To help identify Polydora's current impact among New Brunswick oyster growing areas, this project aims to:

  1. document the presentation and level of the infestation of Polydora;
  2. document the impact of Polydora on overall oyster health; and
  3. document distribution and infestation level of Polydora in relation to environmental conditions.

A better understanding of the increased intensity and prevalence related to environmental conditions and their impact on oyster health would assist industry in developing management and mitigation strategies.

This project supports the optimal fish health objective of the Aquaculture Collaborative Research and Development Program (ACRDP), and pertains to the following 2014-15 national ACRDP priorities: 1) maintaining healthy populations to be proactive in the development of approaches to manage health issues that may arise for cultured shellfish species; 2) management of pests through developing means of understanding and controlling the impacts of pests on cultured stocks and ecological impacts; and 3) environmental impacts from the environment to aquaculture by increasing the knowledge and understanding of how cultured fish health might be impacted by the environment in which they exist and developing means to adapt to, control or mitigate against these impacts.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)


2014 - 2016


Atlantic: Gulf of Maine, Scotian Shelf

Principal Investigator(s)

Daniel Bourque

Mary Stephenson

Collaborative Partner(s)

Huîtres Aquador Oysters Inc.

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