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Quebec Bulletin
June - July 2015/Volume 18/Number 3

Protecting Mussels from Ducks

Flock of ducks over an aquaculture site.
É. Varennes

A new method for protecting mussels will be tested this summer in Chaleur Bay, Quebec. The purpose of the project will be to test the effectiveness of a protective cage against migratory duck predation on commercial mussel sites.
Development of the mussel industry and large‑scale aquaculture operations in coastal waters have inevitably changed the coastal landscape, affecting the fauna that lives there.

Blue mussel production has led to the creation of a new, stable and abundant food source for migrating ducks during their long journeys. In addition, mussel long lines are cast in the same places year after year and their structures often enable ducks to locate them.

As a result, ducks are taking advantage of this new food source. Predation of farmed mussels by diving ducks during their spring and fall migrations has caused significant economic losses in the Atlantic provinces, British Columbia and Quebec.
Although various deterrent techniques are being used to protect crops, most are not sufficiently effective:

  • Reduced efficiency over time because birds grow accustomed to the hazing stimulus (e.g., visual deterrent with scarecrows);
  • Action covers a small area and disturbs neighbours (e.g., noise deterrent using recordings or cannon fire);
  • Significant financial costs (e.g., chasing birds by boat and firing blanks at them); and
  • Reduced production performance (e.g., protective socking equipment).

The most effective method for protecting mussels against ducks seems, for the time being, to be the use of underwater exclusion nets. Because these nets provide a physical barrier, this method eliminates the phenomenon of habituation, making it an effective long-term solution.

The project to be carried out this summer by scientists from the Maurice Lamontagne Institute, in cooperation with local aquaculture companies, will aim to improve this method so that it complies with conservation rules, particularly to:

  • build prototypes of protective cages from commonly used fishery materials available on the local market; and
  • determine the optimal type of net to prevent duck by-catches and the accumulation of biofouling.

The project will also help determine the effectiveness of the protective cage method against duck predation.

André Drapeau
Fisheries Management
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