Octopus washed up on a beach in Ars-en-Ré, in January 2021 -

Pierre Le Gall

  • The Ré Nature Environnement association counted some 200 octopus corpses in mid-January on a beach on the Ile de Ré.

  • This could be due to the cold snap that had occurred a few days earlier, which would have been fatal to a population of females whose eggs had just hatched.

  • The octopus had disappeared from the French Atlantic coast since the mid-1960s, and has started to reappear in recent years.

An "exceptional" phenomenon, and one that Pierre Le Gall had "never seen".

On January 17, this former academic specializing in coastal biology, who has spent “all [his] career on the beach”, and now general secretary of the Ré Nature Environnement association, was alerted to the massive presence of corpses of octopuses, on the beach of La Grange in Ars-en-Ré, west of the island of Ré (Charente-Maritime).

Octopus washed up on a beach in Ars-en-Ré, in January 2021 - Pierre Le Gall

Along with other members of the association, Pierre Le Gall then embarked on the inspection of the beach, scrutinizing the sea leash. “Some 161 corpses were counted on one side, and on the other, we we counted 31 on the only beach of La Grange, details the secretary general.

This distribution shows that this stranding on 2.5 km of beach is not a one-off phenomenon resulting from a direct supply of a defective stock [which a person would have gotten rid of], but that it is directly linked to training. of the sea leash. "

They clearly exhibited unusual grouping behavior

How to explain this massive and unusual stranding?

According to the specialist, the cold snap observed a few days earlier could have been fatal to a population of females whose eggs had just hatched.

"The octopus reproduces only once and while they keep the eggs, the females remain clinging to stones, they no longer move and no longer eat," explains Pierre Le Gall.

Gradually, they weaken, and when the eggs hatch, they die of exhaustion, but one by one and in a scattered fashion.

"There, they obviously had a grouping behavior," which is unusual in the octopus, at least in O

ctopus vulgaris

which is the classic octopus found all over the world.

The only grouping of adults would only happen at the time of reproduction.

The rest of the time,

Octopus vulgaris

 evolves on the bottom of the sea, near the coasts, alone attached to its territory, from which it hunts the intruders.

“It is therefore quite exceptional that we found 200 at once, which is also a minimum because we did not search everywhere.

"

"Species in the process of recovering its populations"

Very present until the 1960s, this species of octopus had disappeared for many years from the French Atlantic coast.

“The octopus regenerates slowly, and it's only been a few years that we start to see it again.

I have seen them in Brittany, Normandy or here.

It is a species in the process of recovering its populations.

This is shown by this exceptional presence of corpses.

The track of pollution, considered at one time, was also quickly ruled out.

"We only found adults, if it had been a pollution, the entire population would have died, and we would certainly have found other species elsewhere," concludes the specialist.

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