The nature of Canet lagoon (part 2)

Following on from the first part of this Canet lagoon series, Leslie McLaren continues her exploration of the coast between Canet en Roussillon and Saint Cyprien.

Canet lagoon and surrounding marshland has long been an important habitat for many different creatures – either as a permanent home or stopping–off place. But now the lagoon has been colonised by vicious invaders that devour everything they can get their claws into. Scientists fear for the eco-system, while fishermen fear for their livelihoods.  

Fishermen’s nets are apparently empty of fish and eels but full of non-native blue crabs (les crabes bleus). Native to the Atlantic coast of America, the crabs most probably got here via ships’ ballast water. Having entered from the sea, in five years they’ve taken over the lagoon.

Their success is partly due to an ability to withstand temperature variation from 6 to 37 degrees and water of variable salinity; they grow fast, have a voracious appetite and no natural predators (after humans) except octopuses. Not many of those in the lagoon!

At present, the only known way of controlling the invasion is to remove as many as possible. In 2021 fishermen voluntarily netted 10 tons. Last year: 14 tons. It’s a never-ending battle but funding has finally been granted to support ongoing removal and further research.  

Other fauna

In summertime you might see birds like the ridiculously lanky Black-winged Stilt (Échasse blanche).  It’s tough for nesting couples, though, because their chicks often fall prey to Marsh Harriers (Busards des roseaux), which also breed here.

Among mammals, there are signs of foxes (renards), polecats (putois) and occasionally even otters (loutres), but because these tend to be nocturnal, they are hard to spot. 

Coypu (les ragondins) are the animals you’re most likely to see in fresh or brackish water around the lagoon. 

Among the reptiles, as well as little lizards that abound throughout the P-O, you may be lucky enough to come across a big and quite rare Ocellated Lizard (le lézard ocellé) basking in the summer sun. They are very shy, however, so won’t hang around once they know you’re there. 

Floridan turtles (les tortues de Floride) are common. While non-native and somewhat invasive, they mainly impact our Mediterranean pond turtles. 

The area covered by water has halved since 1750 and the lagoon is now considered close to the end of its natural evolution, because of urbanization and increasing isolation from the sea, plus diminishing salinity due to freshwater draining in from the plain.

Even if rainfall remains generally as low as last autumn and winter, a freak storm could have a devastating impact. There’s a risk, for example, that it could fill in completely in a single flood event, should the river Réart burst its banks.

It’s up to us to help it endure for as long as possible.