|USE OF RADIO AND ACOUSTIC TRANSMITTERS IN A STUDY FOR THE REINTRODUCTION OF DOMESTIC STURGEON (ACIPENSER NACCARII) IN A LARGE RIVER (PO, ITALY).
Bronzi P.1-2, E. Garofalo2, S. Ceradini2 S. Ansferri 1
1: CIRSPE, via dei Gigli d’Oro 8, Roma
2: CESI S.p.A, via Rubattino 54, Milano
Acipenser naccarii is the endemic species of sturgeon of the main northern Italian water courses, the Po river included. Nowadays it seems completely disappeared due to the general bad quality of the Po ecosystem, overfishing and adverse conditions arose through the construction of a big dam that prevent fish from migrate along the water body.
Nonetheless descendants of the original Italian Acipenser naccarii still exist thanks to the work of an Italian fish farmer (Giovannini G., Orzinuovi, BS) which at the beginning of the seventies transferred a little stock of native individuals to his plant and succeeded in reproducing them without sacrifice at the end of eighties. The reintroduction of Acipenser naccarii within the river Po basin has been the subject of several recent actions, mainly of Lombardy Region, although few is known about the autoecology of this species. One of the aims of this project, funded in the frame of “V° Piano Triennale della Pesca e dell’Acquacoltura” of Ministry of Agriculture and Forestry, was trying to find out how domestic fish, grown and kept in captivity, react when released in the natural waters. Two different techniques of telemetry were initially tested in different environmental conditions: radiometry exhibited a too weak potentiality in relation to this environment due to the high depth and heavy particulate concentration in Po river water. On the contrary, acoustic transmitter showed a high transmission capacity since the signal could be picked up from a distance up to 600 m, in every condition. Acoustic transmitter were then fixed externally on the dorsal scutes of some adult fish released one at a time in the river Po upstream the Isola Serafini dam and close to it. Individual movements along the water body were closely followed for some weeks after releasing. Preliminary data of efficiency of two systems in different water qualities and problems of fish telemetry in this particular conditions are reported.