Zebra mussel

A constant surveillance, forever!

Spring 2022

Spring dives to remove zebra mussels are back on Lake Massawippi for a sprint start, which began on May 2nd. This is a crucial step in a structured plan of attack that will last all season. The goal is to reverse the trend at all costs by preventing the reproduction of young mussels established in 2021.


The spring dives will be accelerated in the coming weeks in collaboration with the MFFP (Ministère des Forêts, de la faune et des parcs), Explos-Nature and MCI (Memphrémagog Conservation Inc.). Divers from the Quebec Aquarium and the Montreal Biodome will join this remarkable scientific team in early June.

At the same time, Fisheries and Oceans Canada (DFO) will be systematically and rapidly analyzing water samples throughout the summer to determine the presence of veliger, a fundamental indicator of the degree of reproduction. Our team collected the first water samples for analysis on May 20.


Fall 2021

The first signs of contamination appeared on October 15, 2021.

Blue Massawippi immediately sounded the alarm so that all efforts were deployed and an action plan put in place to manage this crisis. A crisis management committee was formed to join together Blue Massawippi, the Ministère des Forêts, de la Faune et des Parcs (MFFP), Fisheries and Oceans Canada (DFO), COGESAF and the Regional Massawippi Park.

The committee is advised by Isabelle Picard, senior biologist at Stantec

First, the committee managed the following actions:

  • Temporary closure of lake access EXCEPT for the Massawippi beach, with mandatory boat washing upon entry and exit
  • Exploratory dives on October 20 and 22, 2021
  • Sampling of veliger larvae on October 28, 2021
  • Diving inventory from November 1 to 5, 2021
  • Assessment and intermediate-term action plan on November 10, 2021

Residents, you can help us with this action plan by filling out the RESIDENT-INVENTORY form for your property

Fill out the Resident-Inventory form

In our region and in our lake

Over the past 4 years, the zebra mussel has invaded and contaminated the Eastern Townships. It can be found in the St. Lawrence and Richelieu rivers, in Lake Champlain, but also in Lake Memphremagog, in Lake Magog, in the Magog river and in the St. Francis river. Particularly prolific in 2021, we have seen its population increase considerably in Lake Memphremagog and Lake Magog.

Due to its high calcium content, Lake Massawippi is recognized by experts as the most vulnerable lake in southern Quebec. The zebra mussel will be able to reproduce much faster and cause a lot more damage, which will cause irreversible changes to Lake Massawippi.

Faced with this threat, Blue Massawippi has been following a rigorous detection protocol since 2017, and has multiplied its prevention efforts since then.



The zebra mussel is a small, non-native mollusk that is no larger than a loonie at maturity. The female can lay up to 1,000,000 eggs per year. An aggressive invasive species without predators in Lake Massawippi.

In its country of origin, the zebra mussel prefers minimum calcium concentrations of 25.4 mg/L to 28.3 mg/L. In Lake Massawippi, our 2020 tests show calcium concentrations ranging from 29 mg/L to 34 mg/L. According to experts, Lake Massawippi is a zebra mussel paradise, with optimal breeding conditions.

When they hatch, the larvae, called veliger, are suspended in the water for 15 to 30 days and are easily transported by currents over long distances. They cling to all surfaces: boats, paddles, fishing gear, water skis, boards, etc. They survive several days out of the water, especially in damp crevices, and are invisible to the naked eye The zebra mussel is spread by people who visit contaminated water bodies without following the necessary decontamination measures.


The zebra mussel clings by the millions to all solid surfaces (rocks, docks, boats, water intakes, motors, etc.) and clogs drinking water intakes. It attacks the native mussels and, due to its strong filtering ability, takes in all the plankton that fish need for survival. It’s called an “engineering” species because it modifies the processes of the ecosystem that it contaminates.

In North America, the zebra mussel survives for 3 years. The very sharp shells then settle to the bottom and accumulate, billions of shells washing up on the beaches of severely affected lakes.

Its filtering capacity increases the transparency of the water. The water becomes crystal clear and allows more light to pass through, which favors the development of plants in the depths.

Once established, the zebra mussel cannot be removed. In large lakes, damage to public infrastructure totals tens of millions of dollars each year.

The only solution = prevention

Wash, drain and dry anything that has touched another lake!

Never let anyone bring a boat into the water without a thorough wash first. This has been the law of Lake Massawippi for nearly 25 years.

“The first year there will be a few and in 3 or 4 years, the population could surpass the millions, given the ideal conditions for its proliferation. In 10 years, the trenches and banks of the lake will be carpets of dead mussel shells. Live mussels will line the rocks, docks and boats.” »

August 14, 2020, Isabelle Picard, biol., zebra mussel specialist, principal advisor of the zebra mussel control protocol for Blue Massawippi

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