Il recupero dello storione cobice in Italia - ACTION PLAN -Progetto Life 04NAT/IT/000126 "Conservation and Breeding of Italian Cobice Endemic Sturgeon".

160 Seiten. DOI: 10.13140/2.1.1085.7286.

Abstract:

In the Italian waters there were historicaly three species of sturgeon: Huso huso (Beluga sturgeon), Acipenser sturio (common sturgeon) and Acipenser naccarii (Cobice sturgeon). The first two species are considered as locally extinct, while the Cobice sturgeon is still signalled, even if seldom. There is moreover a population of this species banished to the fresh waters of the Tessin river, an affluent of the Po river, due to the building of the barrage of Serafini Island on the Po river. The main reason that brought the Cobice sturgeon to the danger of extinction is the eccessive fishing pression. Just in recent times legislation protected all three species, completely forbidding their fishing. Different factors contributed to the decline of population, among them the interruption of the fluvial continuity which, preventing the going back up of some intervals of rivers reduced the number of reproductive sites. The biological cycle of the Cobice sturgeon is very long, male specimens reach sexual maturity at 7-11 years of age, with a total length of at least 80 cm, and female specimens at 12-14 years of age, with a length of at least 1 m. The Cobice sturgeon has been object of numerous studies and projects, both of research and conservative. During the years, single Administrations on the whole territory, in particular in Lombardy, Veneto and Emilia-Romagna, have been engaged in local conservation interventions, even with repopulation programs. The population restricted to fresh waters of Tessin has then been object of a specific conservation program guided by the Lombardy Park of the Tessin Valley and co-financed by the European Community through the project LIFE03NAT/IT/000113. Only with the project LIFE04NAT/IT/000126 a common and coordinated commitment on a big area has been started, almost the areale of distribution of the species. This project that lasted three years involved Lombardy, Veneto and Emilia-Romagna. The involvement of regional Bodies, Parks and Province Authorities of three regions has represented a successful prerequisite, as the Cobice sturgeon moves and migrates on a big area, not belongig to a unique jurisdition. The project realization was possible thanks to three solid fundamentals: the experience of the Public Authorities, the availability of a stock of Cobice sturgeon, the gained and consolidated technology for its reproduction and breeding. The stock specimens were captured in the 1970s in the same project area and since then maintained in captivity. This stock and its descendants built the only and fundamental tank for the species rescue. All specimens now kept ex-situ, both by public authorities and private citizens, come from that original centre, whose specimens, still living, are bred and belong to the Azienda VIP of Orzinuovi in Lombardy, breeding site with CITES authorization. The technology for the reproduction and breeding in all life stages of the Cobice sturgeon was worked out in the same facility that was the first to realize the bloodless reproduction of A. naccarii in the 1980s. Afterwards, thanks to the LIFE project, artificial reproduction was carried out also at the public centre of Quinto di Treviso, in Veneto. Thanks to the project LIFE04NAT/IT/000126 the genetic characterization of a part of the specimens kept ex-situ has been carried out and a crioconservation technique of the seed of the Cobice sturgeon has been worked out realizing the germoplasm bank. Thanks to the reproductions of the two breeding centres, an important repopulation effort has been performed. Seeding of 66,038 Cobice sturgeon specimens has been carried out: 17,038 of them had an average length of 50 cm and an average weight of 900 gram, the remaining 49,000 specimens were put at the post-larva stage. The post-larva seeding has been performed according to a successful reproduction of the two centres, so that it goes beyond the plant potentiality to wean a so high number of alevins. For this reason the choice was to release the specimens at this life stage. Before carrying out the repopulation program, the watercourses have been studied in detail, showing important features of the habitat for the Cobice sturgeon, as for example substratum granulometry, stream velocity and bathymetry. Particular attention has been drawn to the presence of holes. In the three regions involved in the project, following rivers have been studied: Po, Adda, Oglio, Mincio, Adige, Bacchiglione, Brenta, Sile, Piave, Livenza, Lemene, Tagliamento. For the evaluation of the repopulation program both campaigns of direct sampling with nets and electrofishing and monitoring campaigns through a national networtk that have involved fishermen for leisure, professional fishermen, volunteers and the staff of the security service of the different Bodies have been carried out. The monitoring network was previously organised, with informative meetings and distribution of materials. Thanks to this organisation, in case a sturgeon was accidentally captured, it was possible to signal it calling the nearest referring centre. As soon as the nearest surveyor received the call, he immediately went to the capture place to verify, with an adequate reader, the presence of microchip and to survey the biometric measures. If no microchip was present, a fin fragment of around 1 cm2 was taken for genetic tagging. The genetic tagging, thanks to the results of the genetic characterization analysis, made it possible to recognise the specimens analysed as descendants of the stocks kept in captivity (F0), deriving then from previous repopulation programs, or as wild. Out of 38 analysed animals, 23 have resulted not assignable to the F0. The organization of the monitoring network had also the aim of awakening the fishermen, but dissemination of the project was spread also among schools, carrying out a specific program of environmental education in which around 500 school groups corresponding to the total involvement of around 10,000 students have been met. The results of the repopulation and of the monitorings carried out both directly and through the survey network have been organized in a Geographical Information system (GIS). The GIS was developed on a geo-database with a geographical reference of the seeding points and the points of capture, to which following information has been added: information of the single specimens sown or captured, as the microchip number, length, weight, genetics of origin, date and place of seeding/capture, etc. These tables were linked with the points with a geographical reference and among them, in order to access all available information through GIS for each of the thousands of specimens having a microchip. This Action Plan for the Cobice sturgeon is the result of the same project but it also considered the Action Plan produced by the Tessin Park for the repopulation at the moment banished to the fresh waters of that river. The action plan was performed on the model of the management Plan and is therefore structured in four sections: knowledge framework; evaluation of the ecologic needs; aims; management strategy. Thanks to this structure one clear general goal was set: the conservation of the A. Naccarii in a satisfying state, as defined by the Habitat Directive. To this follow 14 detailed aims that are functional to the general aim: giving the Sile river the fluvial continuity back; monitoring on some rivers of the dangerous structures for the species; facilitation to the overcoming of barrages; conservation of the habitats where the Cobice sturgeon lives; reduction of the competition with the silurus; reduction of the poaching; awakening of the population to the topic of the conservation; awakening of the authorities; progressive increase of the natural population; ex-situ stock conservation; increase of the genetic diversity of the natural population; increase of the knowledge about the bio-ecology; promotion of a regional, provincial and sector planning and programming system; conservation of the species in the Ticino River. The management stategy analysed moreover the value of the Action Plan, integrating it in the regulations, as the areale of the Cobice sturgeon covers three different regions and it is not restricted to the sites of Rete Natura 2000. Periodical deadlines for the review of the Action Plan have been furthermore set, having the aim of adjusting it to the development of the conservation status of the natural population. Depending on such periodical reviews, some detailed aims have been selected: they cannot be faced in the first deadline, but it will be certainly necessary to consider them in the following reviews. In order to clearly identify how to reach those goals, the management activities were outlined and organized according to the types selected in the “Manual for the management of the Nature Sites 2000” of the Italian Ministry for the Environment: active intervention (IA); regulations (RE); monitoring and/or research programs (MR); didactic programs (PD). Each goal goes back to a structured table with the following items: Goal; Activity description; Implementation timetable; Indicators and parameters; Priorities; Expected results; Costs estimate; Potential programmatic references and financial funds; Person in charge of the implementation.

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