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Conservation of Acipenser naccarii in the River Ticino and in the middle reach of the River Po (ACIPENSER TICINO-LOMB)
Date du début: 1 oct. 2003, Date de fin: 31 oct. 2006 PROJET  TERMINÉ 

Background The Adriatic sturgeon (Acipenser naccarii), a priority species under the Habitats Directive, is endemic to the Adriatic basin. It can attain a length of 150 cm and has a complex lifecycle, characterised by seasonal migrations from the sea to spawning areas, located in the middle reaches of rivers. In the Po river basin, numbers have declined drastically as a result of dams that prevent the sturgeon from reaching its main spawning areas. Water pollution and illegal fishing have also contributed to the decline. The rapid increase in numbers of the Wels catfish (Silurus glanis), a large alien species that occupies the same ecological niche, has also affected the sturgeon. However a “land-locked” population of sturgeon that passes its lifecycle in freshwaters has survived in the lower Ticino River, a Po tributary. The area falls within the perimeter of the Ticino regional park in Lombardy. The genetic isolation of this population will probably end in the next few years as a result of the recent decision by the national electric company, Enel, to create a fish passage through a dam on the Po River, which currently blocks the passage of all fish. The decision has been taken following a study made by the Po river basin authority on the negative impact of the dam on the river ecosystem. Objectives This project, managed by the Lombardy Ticino Park, aimed at protecting the Adriatic sturgeon and improving knowledge of the species. An action plan for the management of the species would be drawn up with a special emphasis on conservation and improvement of the spawning habitat and on restocking. The plan will be prepared after thorough investigation of the ecology of sturgeon. Molecular analyses was planned to detect possible genetic drift of the population and to select specimens for release following extensive captive breeding. The beneficiary would also purchase “fishing rights” on a strategic tract of the Ticino River where the fish breeds, so as to directly control fishing. Surveys on the River Po would be carried out in order to locate other factors which disturb migration. To reduce the numbers of Wels catfish, the project foresaw capture operations. These would also allow collection of biological data in order to obtain a more precise assessment of the extent of competition with the Adriatic sturgeon. Results The main actions aimed at the preservation of the landlocked population of the Adriatic sturgeon in the Ticino River were achieved. This population is adapted to complete its entire lifecycle in freshwater because of the presence of a dam obstructing the fish passage. A survey of sturgeon and other fish species was carried out and information on the autoecology, molecular genetics, reproductive and spatial behaviour was obtained. About 1,828 sturgeons were purchased, bred in captivity, and then marked and released in the Ticino River. A sturgeon action plan was drawn up and adopted by the park authorities that will guarantee the continuation of the sturgeon conservation measures. The fishing right of the Riserva Pesca Vigevano was purchased improving the management of the river and the control of the species of Community interest. It could also serve as an example for other similar river management plans. The sturgeon population is scarcely present in the Ticino River and absent in the Oglio River; the monitoring of the marked sturgeons was carried out notwithstanding the local difficulties. The removal of 2,000 sheatfish was undertaken during the project development. The activities carried out for the sheatfish removal campaign could be used as example for other areas similar to the Ticino River. Dissemination activities were carried out with schools and fishing associations. The project involved the fishing associations, so as to increase the awareness among fishermen, and local restaurateurs.

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