Conservation of Austropotamobius pallipes in two S.. (Austropot. lombardo)
Conservation of Austropotamobius pallipes in two SIC sites of Lombardy
Date du début: 1 oct. 2001,
Date de fin: 30 sept. 2004
Though white-clawed crayfish (Austropotamobius pallipes) have a range covering the entire Italian peninsula, they are confined to the least polluted watercourses. Once also quite widespread in the Po basin, the numbers of this crustacean have fallen steeply. Its decline can be largely explained by the degradation of water quality caused by wastewater discharge and uncontrolled abstraction. In addition, the recent spread of two species of non-native crustaceans has had a negative effect on the crayfish population and has led to an outbreak of a serious fungal infection which devastated the remaining populations. The crayfish are now found in isolated groups that face a high risk of local extinction and loss of genetic diversity. Residual populations remain in the Po Valley, the River Pegorino Valley and the Ticino Valley in Lombardy, but their expansion is limited by poor water quality and the presence of non-native competitors.
The Lambro Valley Nature Park proposed to create a stable population of white-clawed crayfish by reintroducing breeding stock to the Pegorino and Ticino rivers and improving the environmental conditions of these two watercourses. To meet this objective, the first step was to eliminate the uncontrolled abstraction of water for irrigation and the illicit disposal of waste. The non-native crustaceans would be removed and any white-clawed crayfish found will be checked for pathogens. Finally, the project planned to set up a crustacean farm that would make it possible to release at least 3,000 breeding crayfish, which will help to constitute a local population. Parallel to these measures, the quality of the waters, and the presence of crayfish would be monitored.
All the aims of the project for the restoration of the native crayfish were reached. In total 3,006 individuals collected from nature (Oltrepo and Lecco province) were released in the two pSCIs from 2001 to 2004, 1,980 of which in the low course of the Ticino river and 1,026 in the Rio Pegorino.
Genetic and sanitary analyses were undertaken to choose the source populations. All reintroduced animals were permanently marked in order to facilitate monitoring activity. Monitoring before and at the end of the project has shown the extent of the naturalisation of the reintroduced population. The presence of newborns and the overall dispersal patterns of the animals released were observed in both pSCIs. However, further monitoring activities should be carried out in the following years in order to confirm its long-term success.
A population of crayfish was also introduced in a pool of the Ticino Park, and it has been farmed in semi-natural condition. This population will be used as a source for future reintroductions. Water analyses were carried out in the watercourses selected for the reintroductions. Meetings with the citizen of the area near the project site and activities with schools were organised in order to increase the knowledge of this species.
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