The population of cephalopods has exploded over the past two years: in a single trip to sea, the two crew members of the Dishual always bring up several hundred kilos. More and more octopuses are moving through the waters of Morbihan. Although the species from the Breton region is not dangerous for humans, it is of particular concern to fishermen. How different are octopus and squid?
Manhandled by the roll of the waves which are about to break on the coasts of southern Finistère , Jean-Baptiste Fuchs leans over the rail. The sailor seizes the dhan adorned with three yellow and black pennants which marks the beginning of a line of about twenty octopus pots. Grabbing the end handed to him, his skipper starts the trap-turner allowing the traps to be lifted at a regular rate. The ballet of the two sailors is perfectly regulated, their gestures sure: Erwan Le Guilloux hands the plastic containers to his young colleague, who conscientiously arranges them next to each other on the Dishual's deck, without even taking the time to inspect the contents. Here and there, however, we can see suction cups…“When the octopuses are in, there's no point in trying to get them out; they are much too well attached! “ Warns Jean-Baptiste, alias “JB”, who immediately leaves to grab the next container.
Scarcely has the fisherman turned his back when a brownish arm unrolls, feeling the wood of the ship. A second follows a few seconds later, then a third. And suddenly, the octopus(the other name for the octopus) launches out of its lair, soon joined by congeners escaped from neighbouring pots. In a vision worthy of a science fiction film, the viscous bodies move in the middle of the corpses of starfish, in search of a breach towards the big blue... JB then interrupts his umpteenth round trip to take off the escapees from the bridge by pulling on them sharply and throwing them into the large bin provided for the catch of the day. In addition to a few cakes and lobsters, a large handful of prawns and a box of red mullet, mackerel and other sea breams, the Dishual brought some 300 kilos of octopus to the port of Loctudy that day. A completely correct figure the day after the strong gale which forced the skippers of the Route du Rhumto delay their departure in November 2022, but far from the 600 kilos caught during a single session ten days earlier.
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| Erwan Le Guilloux (right) and his second in command have equipped their shellfish collector, the Dishual, to track octopuses. A forced conversion that affects many Breton fishermen. © Heidinger Jean-Marie / Collective Mirage |
Since the summer of 2021, many Breton boats have come to hunt down octopus in this area as big as a pocket handkerchief, somewhere between Île aux Moutons and the Glénan archipelago, off Finistère, where these cephalopods are ravaging shell beds. Other crews tend to concentrate around Belle-Île or Groix. After a few months of trial and error during which the mollusc was brought up at random from pots and nets deployed at sea, local sailors began to specifically target it, encouraged by its profusion and attracted by the remunerative outlets promised by the Spanish market. Landings of Octopus vulgaris, anecdotal yesterday, have become common at auctions in the region, from Quiberon , in Morbihan, to Brest, at the tip of Finistère. An abundance which, on land as well as at sea, upsets the balance. And ask the scientists.
“The volume is such that they are sold in stacks of ten crates” , notes Lucie Dufresnoy, manager of the Concarneau auction, in Finistère, where nearly 1,200 tonnes of octopus were landed during the year 2022. That is two and a half times more than the previous year, and 40 times more than in 2020! She is particularly surprised by the constancy of prices:
"It does not move: the “size 1” [two to three kilos] sells for 8 to 8.50 euros and the “super” [more than three kilos] is around 9 to 9.50 euros. It never fluctuates by more than 50 cents, when the price of langoustine can vary by 5 or 6 euros overnight. It is completely incomprehensible!"
First perceived as an invader by sailors, the octopus is worth gold
At the first signs of the animal proliferating in Breton waters, fishermen initially considered it an invasive species to be eliminated. What they didn't know then was that they were actually getting their hands on a priceless hoard. On the quays in the region, there is talk of exorbitant income – even if it means breaking the rules, such as the one limiting the number of octopus traps simultaneously launched to 400 per boat. Some speak, on condition of anonymity, of monthly incomes of more than 10,000 euros for simple sailors. And more for their bosses. A gold rush. What the fisherman Laurent Deniel, 41, crossed on a pontoon in Concarneau, summarises as follows:
Whoever says octopus hasn't changed his life is a liar!
He himself reconverted his 9.60 meter dredger, with the predestined name of Octopus – “like the villain of Batman” , he specifies – for tracking octopuses: “They are often found on seashell beds , he explains. There were so many traps in these areas that I could no longer pass the dredge… I had to do something else. “ Without great regrets, however. Because the forty-year-old readily admits it: “Inevitably, I would have ended up getting into it, because it pays off and it would be silly not to take advantage of it, especially in these times …”
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| Tons of octopus are landed every day at the Concarneau auction. A godsend, because these catches are sold at a good price, little subject to fluctuations. © Heidinger Jean-Marie / Collective Mirage |
Erwan Le Guilloux, 44, had to decide to follow the same path with his versatile shellfish. "We were the first to complain and to call for meetings to settle these disputes over the occupation of maritime space ," he says. There is an area that is normally reserved for flirts but even we have set octopus traps on it. Misplaced by sailors or deflected by currents, the strings of traps and pots are regularly intertwined. So much so that the Loctudy fisherman made the decision to no longer work at night, despite better yields. "The risk-benefit ratio is not worth it, " he says.It's the Wild West: there are lines everywhere! We run a risk to have such a mess on the water.
Before opting for commercial fishing, Erwan Le Guilloux traveled from Africa to Antarctica , during a long course of studies in marine biology . From these years spent with scientists, he has retained a keen sense of observation and analysis. However, he struggles to explain the sudden invasion of octopus in his fishing area.
He is not the only one. Martial Laurans, biologist at Ifremer, the French Research Institute for the Exploitation of the Sea, is precisely working on the subject. For thirty years, hardly a week has passed without this enthusiast diving into the waters of the Iroise Sea, which bathes Finistère. "The first octopuses I saw date back ten years," he says. Since then, divers and fishermen have been coming out more and more. In fact, it's a gradual return, not a sudden arrival. The researcher found traces of documents that suggest a presence of the octopus in the Breton waves dating back more than a century, then noted "periods without any reports".
An intermittent presence that raises questions for him, and for which he points to the very harsh winter of 1962-63 as a turning point: “It was undoubtedly a major event. Following that winter, many species became much less abundant: crabs, scallop. In Brittany, the octopus then disappeared from the radar. Until his return, therefore, at the beginning of the 2010s. "We can think that he took all that time to come back and recolonise certain places" , continues Martial Laurans.
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| A cephalopod tries to escape by clinging to the leg of a sailor… The species had almost disappeared from Brittany for sixty years. The pot is another fishing technique for catching octopus. The cephalopod finds refuge in it when the trap is under water. Once the line is raised, the octopuses are extracted and placed in tanks. © Heidinger Jean-Marie / Collective Mirage |
A scenario approved by Julien Dubreuil, marine biologist and project manager for the Regional Committee for Maritime Fisheries and Marine Farming in Brittany:
“For a decade, we had seen landings, but it was anecdotal, barely a few hundred kilos here and there depending on the ports , he testifies. And suddenly, in 2021, we observed a population explosion in Octopus vulgaris. »A phenomenon all the more strange that another octopus, Eledone cirrhosa, also present in the region but much less sought after by fishermen, does not seem to multiply in the same way… How then to explain this proliferation of the common octopus? Could global warming, which affects the oceans and goes hand in hand with acidification of the waters, be favorable to the cephalopod? Should we look at the side of the disruption of the food chain? Would the octopus take advantage of the very low presence in the area of its predators, conger eels, moray eels, dolphins , porpoises and seals ? Rather than these avenues, mentioned at first, Martial Laurans and Julien Dubreuil today favor that of the "threshold effect", the result of a combination of a sufficiently large number of adults, favourable environmental conditions for excellent reproduction, and good food availability. For Julien Dubreuil, “the big question mark is the exact modalities of the combination of all these factors” .
Jean-Paul Robin, doctor in biological oceanology and specialist in cephalopod migration, also rules out the hypothesis of a massive and sudden migration of the octopus. " In the family of cephalopods, octopuses are probably the most sedentary ," he explains. He notes two exceptions to this particularity: " First when the eggs hatch: the juveniles are planktonic , that is to say they have the ability to position themselves vertically in the water column but remain dependent on horizontal currents for their movements, he says.Then depending on the season: the octopuses tend to go deeper in winter, in order to protect themselves from the desalination linked to precipitation. But we are talking about small movements, which are only made over a few nautical miles!”
Sustainable fishing objectives in France are far from being achieved, according to Ifremer
With a boundless appetite, the octopus raids, goodbye clams and abalones!
Month after month, scientists are accumulating data and knowledge which, in time, should enable them to project the duration, extent and consequences of this proliferation in Brittany's waters. During his underwater excursions Martial Laurans had the opportunity to observe the animal for a long time, which his trained eye easily spotted. Barring exceptions, the octopus is never found in the water column, where it would probably expose itself too much to predators. It is a benthic animal, that is to say, it lives on the bottom, where it makes use of its impressive capacities for mimicry.
Scientists and fishermen seem to agree on the fact that octopuses enjoy frequenting sandy bottoms, where they feast on shellfish. "In terms of food, the octopus is quite opportunistic: it feeds on what is easiest to catch" , suggests Dominique Barthelemy, curator of the living environment at the aquarium of Océanopolis, in Brest, who points in particular to the taste of the beast for depredation. In other words, the animal loves to feed on prey already captured in the traps and nets of fishermen. "If the octopus had a motto, it would be 'eat as much as possible to grow as quickly as possible'" , laughs the expert.
Because the life of an octopus is short: two to three years maximum. And during this brief existence, each individual actually experiences exponential growth: a larva can very quickly reach seven or eight kilos for the largest specimens. The problem? The Glénan scallops have already borne the brunt of this boundless appetite, disappearing almost completely. And those of the harbour of Brest, where the octopus landed in 2022, are promised the same fate. We cannot yet draw conclusions for what will happen to its other prey, but the voracity of Octopus vulgaris worries fishermen, who have already seen abalones, clams and razor clams become scarce in recent months. “There is apprehension, for sure. We don't know what tomorrow will bring.", admits Erwan Le Guilloux, who fears finding a devastated ecosystem the day when, perhaps just as suddenly as it came, the cephalopod will disappear from Brittany .
An ecosystem unbalanced by a species that takes precedence over all the others
Because, like what has already been observed off Senegal and Gambia from 1986, "we know that the octopus population can suddenly increase, then decrease" , warns the biologist Julien Dubreuil. In question: the short life expectancy of the animal, which mechanically favors a great variability of the biomass . “The capacities of the ecosystem cannot be extended,” continues the specialist. It takes food to feed this large number of octopuses and, at some point, it will be in limited supply. »Julien Dubreuil is careful not to draw hasty conclusions on the duration of the overabundance of Octopus vulgaris, but is already worried:
The problem is that the environment is already completely unbalanced, with one species taking precedence over all the others...
A valid observation in the seabed but also in the auctions, where octopus vampirizes sales, at the risk of upsetting the economic balance. "All the fishermen go for octopus because it's easy and it pays off," summarises Lucie Dufresnoy, the manager of the Concarneau auction. But the fishmongers have no more fish to sell and are afraid to go out of business. An alarmist speech, but which could prove to be prescient. “ When the octopus disappears overnight as it did in the 1960s, fishermen will go back to fish, but to sell it to whom, if all the fishmongers have closed? “ , she wonders.
For the time being, Breton octopus is still surging on Spanish stalls. Brittany, she always seems to be sulking about the amazing animal of which she knows almost nothing. “The octopus has not yet entered the local culture, observes Martial Laurans. Here, people don't know how to cook it. Cuttlefish , yes, but not octopus. “ Since we may have to get used to its flaccid presence on the coast, restaurateurs and simple apprentice cooks are nevertheless every day a little more numerous to take an interest in the beast. Who knows, maybe one day the octopus will become the star of recipe books here and find its place on the tables of the region...
The octopus, a brilliant but rambunctious student
Use of tools, tricks to escape predators and spectacular hunting parties… The octopus demonstrates exceptional cognitive abilities. Here are four of its distinctive points:
Perfect coordination
Particularly flexible, the octopus never tangles its arms. And for good reason: if it only has a brain to coordinate its eight limbs, it has as many nerve ganglia as tentacles, which allows each entity, by initiating decision-making, to act autonomously. . "Octopuses will rather use the front of the body to grab objects, and the back to move around," says Lisa Poncet, a doctoral student at the University of Caen- Normandy. Their arms make it possible to recover tactile information, but also gustatory and olfactory. We can say that they “taste” their environment with their suckers. »
A gift for hide and seek
Among the behaviours observed, the octopus' ability to camouflage is undoubtedly the most surprising. “It can very easily change color thanks to cells, chromatophores, sorts of bags of pigments, underlines Dominique Barthelemy, curator of the living environment at Océanopolis, in Brest. If the octopus wants to become dark, the bags spread out until they become joined; if it needs to turn white, it retracts the contents of the bags, revealing its immaculate flesh.
An incredible sense of adaptation
According to Lisa Poncet, the intelligence of the octopus lies above all in its memory, in its spatial and social learning "very similar to what we find in mammals" , as well as in its total adaptation to its environment. To feed on shellfish, for example, "he is able to drill a small hole in the shell and inject a paralytic so that it can open more easily, and he knows that this paralytic must not be injected in the same place according to the targeted species! »
A slightly distracted side
Lisa Poncet, who studies two species of cephalopods, Octopus vulgaris and Sepia officinalis (the common cuttlefish), describes the octopus as a bright, but rowdy and unruly student. “When it is 'asked', such as distinguishing a vertical rectangle from a horizontal rectangle in order to obtain a reward, the octopus is much messier than the cuttlefish, which has a calm and reflective side. Octopus vulgaris is more curious, very explorer. And sometimes it's even hard to get his attention! »
Full story from SYLVAIN MOREAU Posted on 04/19/2023
