Invasive green crab covers the shores of Vancouver Island

Carcinus maenasfrom the Latin name European green crab, from the common name it is up to ten centimeters in size, and according to the International Union for Conservation of Nature, it is one of the 100 most invasive species in the world.

It was in New Brunswick in 1951 that this small coastal crab, described as aggressive and energetic and able to survive without water for several days, was first observed in Canada.

Since then, he has conquered the Atlantic coast and made his way to the west coast in the late 1990s through ocean currents and the dumping of ballast from ships.

In British Columbia, crustaceans are multiplying at an alarming rate, mainly on the west and south coasts of Vancouver Island, and its presence in the Salish Sea has recently been reported.

Thomas Terrio is a scientist and researcher. He has been studying invasive aquatic species for over 15 years.

At Canada’s Fisheries and Oceans Biological Station in Nanaimo, he explains that from an ecological point of view, the European green crab competes with native species.

They can destroy the habitat of an entire ecosystem. They feed on other crustaceans, devour small Dangenes crabs, mollusk populations and destroy the seaweed needed for young salmon.continues Thomas Terrio.

Due to its predatory behavior, the green crab also threatens the traditional fish resources of the coastal first nations.

If you combine all these aspects, their impact can be very seriousemphasizes Thomas Terrio.

So far, observations

We do not have an estimate of their population in British Columbia, but I know that the Tofino Coastal and First Restoration Society’s harvest is very high.says the scientist.

According to Thomas Terrio, a recent surveillance and capture program has taken over 000crabes verts par semaine”,”text”:”environ 10000crabes verts par semaine”}}”>about 10,000 green crabs a week. A figure that can be achieved even every day in the bays of Klayokot and Suke.

We need to react urgently, because it can get out of control very quickly. »

The quote h Gordon Plains, leader of the first nation of T’Su-ke.

000œufs par an. Si vous vous promenez sur la plage, vous pouvez voir des petits crabes verts courir partout. Ils sont très invasifs”,”text”:”Le problème, c’est qu’ils peuvent avoir beaucoup de bébés. La femelle peut pondre jusqu’à 185000œufs par an. Si vous vous promenez sur la plage, vous pouvez voir des petits crabes verts courir partout. Ils sont très invasifs”}}”>The problem is that they can have many children. The female can lay up to 185,000 eggs a year. If you walk on the beach, you can see little green crabs running. They are very invasivecomplains Gordon Plains, leader of the first nation of T’Su-ke.

If Thomas Terrio points out that not everyone reaches adulthood, he confirms that this figure is correct.

To date, First Nation members in partnership with the province and Fisheries and Oceans Canada have caught 75,000 European green crabs using modified crab traps.

But we have to constantly monitor, because the population is growing very fastcontinues Gordon Planes.

Despite its name, green crab is not always this color, and can be brown or red. Its five clear spines on both sides of the eye distinguish it from other species of crabs.

Photo: Emily Grasson / WSG Crab Team

I don’t think we really realize the scale of this problemsays Gordon Plains, who is campaigning with provincial and federal governments to create a control program.

If nothing is done, all this will negatively affect the environment for decades to come.he concludes.

Washington State responds

In waters adjacent to the U.S. border state of Washington, green crab populations along the coast and Puget Sound according to the US Institute of Geological Research, from 2019 to 2021 increased by almost 5500%.

The institute has shown that one crab can eat up to 22 shellfish a day, threatening the shellfish industry, which brings in $ 270 million to the state treasury.

In addition, the governor of Washington issued an emergency statement this year, as more than 70,000 European green crabs were caught near Bellingham last year.

According to the British Columbia government, the fisheries and aquaculture industry generated $ 667.4 million in 2011, or 0.4% of the province’s gross domestic product (GDP), and may also be at risk.

Shell, biopolymers and reduction

Although the green crab is edible, there is currently no industrial or even commercial interest in harvesting it, and field staff are tasked with killing them after being caught. But other options are being considered.

Audrey Moores is an associate professor of chemistry at McGill University in Montreal. She is working to transform crustacean shells into innovative materials.

In particular, she developed a bioplast from green crabs caught in the waters of Kejimkujik National Park in Nova Scotia.

Audrey Moores explains that the crab shell, which makes up 10 to 30% of its weight, contains a biopolymer of chitin.

Tall grasses are disturbed by the current at the bottom of the sea at very shallow depths.

Green crab feeds on other crustaceans and mollusks. It also destroys eels, a seaweed that is the main habitat of young salmon.

Photo: kindly / Arno Lebris

Chitin is a very interesting polymer because it can be converted to chitosan, which has applications in many fields, such as nutraceuticals or biomedicine, as well as in wastewater treatment or fertilizer preparation.more Audrey Moors

So, there are markets to evaluate this invasive species, but the problem is that crustaceans talk to chitosan powder.

There are companies, particularly in Asia, that carry out large-scale industrial processing with chemical processes, which I would describe as quite dirty, with very viscous and very corrosive liquids that form toxic wastewater. continues Audrey Moors.

These transformation processes are difficult to transfer to Canada, which has more restrictive environmental legislation.

Audrey Moores is also working on developing a solvent-free chitin extraction process. This is a method that would be compatible with Canadian labor law and environmental law.admires Mrs. Moore.

Parks Canada recently offered a grant to support research and work in this area.

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