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Hope is reborn for the European sea sturgeon

26.09.2007
A first release of 3000 European sea sturgeons, Acipenser sturio, took place today in Dordogne, in the Saint-Jean-de-Blaignac / Pessacsur- Dordogne sector, with Madame Nathalie KOSCIUSKO-MORIZET, the Secretary of State for Ecology in attendance.

The Minister then visited the experimental station operated by the Cemagref (Research Institute for Agricultural and Environmental Engineering) at Saint-Seurin-sur-l’Isle (in the Gironde department). She then hailed the work of the researchers, engineers,and technicians who succeeded, on 25 June of this year, the first artificial reproduction of the European sea sturgeon from specimens raised in captivity.

The birth of 11,000 larvae is an important advance in the restoration of this species, part of a programme within the National Strategy for Biodiversity.

Until the 19th century, the European sea sturgeon, Acipenser sturio, inhabited most of Western Europe’s rivers. Today, only a few thousand individuals subsist, all natives of the Gironde. Even though it has been a protected species in France since 1982 and in Europe since 1988, the last population has continued to decline. This successful artificial reproduction compensates for the absence of any reproduction observed since 1994 in Gironde, because returning parents have become rare.

At the hatchery for 3 months, the European sea sturgeon were given attentive care that included following their growth and health. First they were fed day and night with tiny shell fish (Artemia salina), then with sand worms (Chironomus sp.) before they were offered a diversified feed of natural foods (chironomids, mussels, shrimp) completed by artificial foods. Their survival rate was excellent (68% for the overall period) and they currently weigh an average of 3.4 g and are 100 mm long.

Today 7500 young sturgeons are ready to join their natural milieu. A second batch will be released into the Garonne on 24 September in the Meilhansur-Garonne sector. All the fish will have been marked by immersion in a chemical substance that fixes in the bone structures so that they can later be identified.

In addition, two small groups of fish will be preserved in captivity until summer 2008, when they will have reached a sufficient size to be equipped with transmitters and released. This will allow researchers to follow their movements in the rivers and then the estuary to gain knowledge on the habitats the fish go to at this stage of development and thus preserve these areas better.

Finally, 1200 young fish will remain in captivity to reinforce two captive stocks that make up the foundation of the conservation and restoration programme for this zpecies on the European scale: one is situated in France (the Cemagref station in Saint-Seurin-sur-l’Isle) and the other in Germany (Berlin’s Freshwater Institute).

This stock will produce the future parent fish (in a dozen years) on which pursuit of future restoration programmes will depend.

The last successful artificial reproduction dates back to 1995. Obtained at that time with wild parent fish, this programme reinforced the relict population in the natural milieu naturel because 9000 larvae and young fish were released into the Garonne and Dordogne rivers. However, the scarcity of returning wild parent fish made a renewed attempt at reproduction impossible, which explains the strategy of preserving juveniles in captivity over the long term to produce parent fish.

These encouraging results crown more than 25 years of research conducted by the Cemagref and its scientific partners (University of Bordeaux I and Berlin’s Freshwater Institute), both in natural milieu and in captivity. This research has notably been financed by the European Union (LIFE-Nature supported by EPIDOR and Feder), The Ministry of Ecology, the Aquitaine and Poitou-Charentes regions, the Charente-Maritime and Gironde departments, and the Adour Garonne water agency.

This research continues within a national consortium coordinated by WWF France and groups scientific organizations as well as public institutions organized around river basins: EPIDOR (the Dordogne river basin), SMEAG (the Garonne river basin) and SMIDDEST (the Gironde estuary), as well as the CNPMEM (National Committee for Maritime Fisheries and Marine Farming).

Awareness campaigns on the situation of the species, aiming notably at preserving the habitats used by these fish and llimiting the risks in case of accidental capture – indispensable conditions for restoring the population – also benefit from the involvement of local fishermen’s associations, associations for the protection of wildlife, and specific associations for the preservation of sturgeons.

The European sea sturgeon, Acipenser sturio, is indeed a species that is strictly protected by several international agreements (CITES, the Bern agreements) and European directives (fauna, flora, habitat; OSPAR). A plan for preserving the pecies on the European scale is being finalized under the auspices of the Bern agreement.

Hope is being reborn for the Acipenser sturio, whose sufficient numbers in the coming years may make it possible to revive the dynamics of the last population in the world. New perspectives for reintroducing the European sea sturgeon, over time, to other river basins belonging to the historical territory of this species are opened up, subject to the conditions of the milieux, control of the pressures these fish are subjected to (notably from captures) and the will to restore the aquatic biodiversity that is favorable to this type of operation.

Marie Signoret | alfa
Further information:
http://www.cemagref.fr/Informations/Actualites/

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