JULIEN MARCHAL - Between oysters and dolphins, the Arcachon basin (2005)

From March 31 to April 7, 2005

It happened in my childhood to come on vacation in the Aquitaine region with my parents. We were in Lacanau to enjoy the Atlantic Ocean and its region. However, I never had the opportunity to come to the Arcachon basin.
It was a great opportunity to come to Gujan-Mestras for a week. Small village of fishermen and oyster farmers, located at the edge of the basin where the rhythm of life turns around the oysters and the tides. Moreover, I had heard about sedentary dolphins visible in front of the Dune de Pilat.

The Arcachon basin is in fact a lagoon on the edge of the Atlantic Ocean. With an area of 155 km2, triangular in shape, it extends over 25,000 hectares. Its depth is variable and can reach about twenty meters.

With an average width of 3 kilometers, the entrance corridor of the Arcachon Basin is delimited by the Dune du Pyla to the south and by the Pointe du Cap-Ferret to the north. Between the two, vast sandbanks, including the famous Banc d'Arguin, draw narrow passes constituting the only navigable access routes between the Arcachon Basin and the Atlantic Ocean.

In front of the Cap-Ferret point, 110 meters high, 2800 meters long and 500 meters wide with its 62 million m3 of sand, records are reached. It is the largest dune in Europe. With a breathtaking view of the entrance to the Basin and the Landes pine forest, the "Grande Dune" is the most visited site on the Gironde coastline with more than a million visitors per year. The Dune du Pyla is classified as a "Grand Site National" since 1978.

In the host family, I met Fred, an oyster farmer for 5 years after various experiences in the trade and travels all over the world. On Friday, he proposed me a boat trip in the basin. He wanted to show me the place and fish wild oysters for his daughter's birthday. Luckily, the tide started to go out, the day was sunny and the wind was light. We left the port of Gujan in the early afternoon aboard a "plate", a flat stainless steel boat capable of transporting oysters and lifting them by hand or by crane. As we had some time, my curiosity led me to ask him to explain his work to me.

The culture of the oyster works in three stages:

We use limed tiles or cups (mixture of lime, sand and sea water) to catch the "spat" (baby oysters) during the summer. These will cling to the tiles with the current for three to six months. The tiles are transported to the basin by boat at a rate of about two hundred and fifty tiles per pallet. They are laid on tile yards and covered with 4.50 meters of water, up to 6 meters at high tide.

Then, the tiles are scraped to remove the "spats" and place them in a "pocket" or "ambulance. Made of mesh, its size is one meter by fifty centimeters. Six "pockets" are carefully placed on "building sites", tables with a diameter of 16 to 20 mm and feet 50 cm high. The oyster farmer has the choice between putting the "bags" on this type of "building sites" or throwing the oysters on the ground (ground culture). From the 18th month, the "bags" are removed and taken to the shack (wooden house where the oysters are stored and sold) in order to detach the oysters, i.e. separate them from each other. The oyster farmer also brings them back in order to split them or to boil them (to kill the undesirable "spat" for the development of the oyster). They are soaked for three seconds in boiling water.

After thirty and forty-eight months in the pockets, they are brought back to land in order to calibrate them by size and to sell them.

The Arcachon basin is the leading producer of "spat" in France with 70% of the production. This is sold in particular in Brittany, Normandy and the Thau basin in Sète.

I understood then that Fred's life is not simple and difficult. It is obvious that you have to love this work. In 10 years the number of oyster farmers has decreased by half. He works from Monday to Sunday, all year round, even with a 2.50 meter swell when the wind is strong.

From his boat, we go through the channel of Gujan, towards the "Cabanes Tchanquées". He wants to show me these old wooden houses mounted on stilts, stuck to the Bird Island, where oyster farmers used to live all year round! From there, we went on the Teychan channel, by the Cap Ferret lighthouse and up the Piquet channel until we reached an oyster park, named "Guian", whose owner is Mr. Bonnot Adrien. The meeting with this young oyster farmer in the middle of his park was strong. He bought several oyster beds with his wife to create his own business and sell his oysters in his hut in "Cassy", a small fishing village located in front of Arcachon. I helped Adrien to move these "pockets" with high boots in a deep mud. Physically very trying. The wild oysters were not there. Adrien offered us to follow him by boat with his dog to his second park called "Estoy de Marens". My first oyster catch was good but we were not completely satisfied! However, our basket was starting to be full. I was happy to be able to visit several oyster beds. He had arranged small oysters scattered on the ground between four spikes. This ingenious method favors the growth of the oyster. Several times he asked me to be careful where I walked so as not to damage them. The picking was easy and the tasting was excellent! The day passed and then we decided to return slowly, waiting for the high tide to return to the port.

Fred had told me about dolphins in the Arcachon basin. And since ancient times, the presence of dephinids has been mentioned.

I had then the reflex to look at my "Alphabets of the Dolphins", and to find in part "dolphins, Arcachon (basin)" and the reference of the book of Brigitte Sifaoui (Editions Atlas). I was able to obtain the address of the association G.R.E.M.S : Groupe de Recherche et d'Etude des Mammifères Marins (Group for Research and Study of Marine Mammals) in Gujan-Mestras, but without a phone number. Coming back from a walk, I went to run to the other end of the village and try to find the house. When I got to the house, there was no name on the mailbox and several houses had the same address! I finally met Mr. Boubert Jean-Jacques, in charge of protecting the natural reserve of the arguin bank, located in front of the dune of Pilat. He was in charge, among other things, of taking care of the association on dolphins created by the S.E.P.A.N.S.O, the federation of the Societies for the Study, the Protection and the Development of the Nature in the Southwest. A little surprised to see me all sweaty, he granted me a few minutes. My disappointment was immediate when he told me that the group of sedentary dolphins had not existed for a long time. In fact all of them were dead! So the association created for this purpose was almost extinct since a few years. He offered me the magazine of "Sud-Ouest Nature n°81/1988, Les dauphins du bassin d'Arcachon" reporting all their works since 1988. The next day, he called me to give me a scientific report by Mr. Ferrey Marc published in the "Terre et la Vie, revue d'écologie n°3, juillet-septembre 1993, Statut et comportement social du Grand Dauphin ( Tursiops truncatus ) dans le bassin d'Arcachon".

Indeed, the creation of the association dates back to 1989, one year after the first photographs were taken of bottlenose dolphins, Tursiops truncatus, in the basin. It was Mr. Ferrey Marc, scientist and dolphin specialist, who proposed to Mr. Boubert to participate in the study of cetaceans. Not sure that this complicity would be fruitful, he accepted out of curiosity. Between 1988 and 1996, a thousand hours of research and more than eight thousand identifications by individual photographs were carried out on the dolphins. The sedentary group was six in number, their names were "Egoïne", "Petite Faucille", "Vire", "Grande Faucille", "Oméga" and "François". The first one was a female because she was with her baby named "Petite Faucille". Later, the team determined that "Little Sickle" was also a female. The bond between the two formed the core of the group and lasted until the end of 1995.

Very often the team observed that the dolphins "Vire" and "Big Sickle" accompanied "Little Sickle" when its mother was obliged to leave. This characteristic behavior of female dolphins helping the mother to protect her calf is cited in all scientific studies on Tursiops truncatus around the world, in order to give the calf the best chance of survival. Therefore, the G.R.E.M.S. decided to believe in the presence of two other females accompanying the mother and her pup. The sex of the female "François" could only be determined after a few hours of diving with her: it was a female. She had a solitary behavior and was observed in the group only once in two. Her contacts with humans were particular and touching.

The "Omega" dolphin had its fin cut in the shape of an omega, hence its name. Aggressive and vigilant, the animal used to watch the group against intruders and the presence of boats. Nobody knew if this dolphin was male or female. But the absence of births in this group of six dolphins for more than ten years made the team wonder about its effectiveness as a male. "Omega" played the role of the protective male, patriarch of a harem, attentive and indispensable to the survival of the five females.

G.R.E.M.S. had noticed that the five dolphins were always on their guard, wary and fearful of the team. However, meeting them every year should have allowed them to approach them better. This behavior was stigmatized by moving in a compact and orderly formation and by long dives. The territory of the Bay of Arcachon inspired a real danger, the channels, sandbanks, tides, currents, nets, oyster beds requiring a constant vigilance.

Despite the massacres, six sedentary dolphins survived for a very long time on the French Atlantic coast. But, slowly the group disappeared over the years. "Vire" died at the age of 45 and then the others. Some of them were found washed up on the beaches. No births had been noted. However, a female can give birth every three years. The number of animals decreased significantly and the last individual disappeared in 2001. The team hoped that "Omega" would be a male, but it must not have been the case. All this is sad for our heritage and the G.R.E.E.MS team who had invested so much to keep them alive.

I thank all those I met around the tank during this week, Fred and his family, Mr. Bonnot, Mr. Boubert for his patience and his passion, with the regret of not having met dolphins, but we do not control nature and fortunately.