Recovery of the sturgeon monitoring buoy at Isola Serafini
As you know the newsletters want to represent not only a moment of information on the activities carried out by the project, but also a tool to tell the small and big stories that are happening behind the scenes, but are of great importance to achieve the project goals. In this direction should be seen the recovery of the sonar buoy at Isola Serafini.
To better understand the eco-ethology of sturgeons in the Po river, 100 adult specimens were fitted with sonar emitters before their release into the river.
These instruments, 8 cm long by 2 in diameter, are inserted into the subject's abdomen by means of a small incision, and each is coded to emit a specific impulse that makes that subject identifiable by all the others released; thanks to the internal battery power and reduced emission consumption, they allow to follow the sturgeons for about 3 years from their release.
For the signals emitted by the specimens, the project has activated a double monitoring network: fixed buoys positioned at strategic points, and monitoring campaigns by boat with portable hydrophone. As shown in the following figure, the 6 fixed receivers have been positioned to cover the entire release area: from the Ticino (buoy positioned at Bereguardo), to Isola Serafini (buoy upstream of the fish passage) until before the Po delta (Ferrara Canottieri, and Ro Ferrarese, for the Emilian shore, Occhiobello and Papozze, for the Rovigo area).
Location of the 6 fixed sonar buoys for the monitoring of sturgeons released with sonar tag.
At the end of last year, while the monitoring officers of the province of Piacenza were carrying out the recovery of the buoy positioned at Isola Serafini for the periodic discharge of data, there was a break in the steel cable that held the receiver, due to the corrosion for the galvanic currents present in the area.
Immediately the Province of Piacenza staff were active in order to proceed with the recovery of the instrument, but the thing was not straightforward, having to operate within the reservoir of the Isola Serafini hydroelectric plant, characterized by: strong current generated by the hydraulic jump for the turbines, turbidity and a river floor with sediment accumulation.
It was therefore necessary to have highly qualified personnel to operate in these critical situations; for this reason, the Diving Club of the Civil Protection of Piacenza has been called, which has given its full availability to proceed.
Thanks also to the active collaboration of Enel Green Power, Sunday 5 November 2017 at 8.30 am the recovery operations began, despite an inclement day characterized by rain and a rather low temperature, conditions not exactly ideal for diving in the river.
The staff of the divers group of Piacenza put the support vessel in the water, and after loading the support equipment moved to the dam. When they got there they placed, with the help of the remaining personnel on the ground, a pair of ropes anchored to the river floor with the function of a guide wire.
All the safety devices were checked, while on the boat two divers were prepared for the dive.
The divers went down into the water and secured to the guide ropes started the search for the buoy with the help of a lighthouse, given the remarkable water turbidity.
After a few minutes they emerged bringing to the surface the buoy that lay on the river floor about 10 meters deep.
After a careful check of its functionality, the buoy has been repositioned in place and has restarted its work of recording any on-site presence of marked sturgeon specimens.