The return of the long way migrants
Life Project “Con.Flu.Po”: the construction of the biggest fish passage in Italy.
The fish are maybe the most free creatures that lives next to us: they move invisibles and undisturbed under the surface of streams, rivers and lakes, they are ignored by the common persons and followed only by the patient anglers. We often forget about them, more silent than the birds in the sky and less photographed than the mammals in the woods.
The fish swim, the fish go everywhere. Or almost.
Why are some of the species caught by the grandpa missing today? The answer is paradoxically in a question: what does a fish do when it finds a dam in front of it?
It stops. It has inexorably to give up, especially, if it finds the obstacle on its way up-stream. For the fish is very important to move: whether they are great migrants (sturgeon, eel, twait shad and salmon), or species that move for few kilometers or almost completely sedentary species. Everyone knows the immense effort of the salmons for the reproduction, during their migration up-stream from the sea to the river where they were born; let us even remember the incredible journey of the glass eel, from the Gulf of Mexico up to our lakes, gently pushed from the Gulf stream: these miracles of the nature become impossible when we place dams or others barriers on their route. It happens that the fish, in the best-case scenario, be content with unsuitable habitats, disappearing from the lakes at the foot of the Alps and stopping themselves much more downstream of what their instinct suggests them.
The solution to the issue exists: similar to the tunnel used to avoid the road crossing of the wild animals, the fish passages are genuine “stairs of water” made to let the fish cross the barriers built by the humans, to naturally accomplish their life cycle.
The biggest fish passage in Italy is currently under construction near the only one barrier of the Po River lowland stretch: the Isola Serafini Dam (Monticelli d’Ongina, Piacenza, Lombardy, Italy) for hydroelectric use, in concession to Enel Green Power S.p.a..
Restoring the Po River connectivity is the watchword of the Life-Nature Project (Life11nat/it/188 “Con.Flu.Po”), which intervenes on the basin with the highest biodiversity in our Country. The project is financed by the European Community and Regione Lombardia–DG Agricoltura leads a prestigious partnership with Regione Emilia Romagna, Agenzia Interregionale per il fiume Po, Autorità di bacino del fiume Po, Parco Lombardo della Valle del Ticino, Provincia di Piacenza e di Rovigo and GRAIA.
It was necessary to design two fishway entrances (one for each of the two branches of the Po) that successively links in a single channel. The numbers are astonishing: 635 meters of total length; a discharge of 4 m3/s that will flow in two channels 2,8 m wide and dug up to 10,8 m under the campaign plan. The fish passage is provided with a monitoring room with a window overlooking the channel (to monitor the fish transit); a capture cage made to grant the study of the transiting fish or to pick the most harmful species up. The project includes even the livestock and the release of juvenile specimens of the very rare adriatic sturgeon (Acipenser naccarii) and other native threatened species.
The realization of the gargantuan structure confirms the efforts of Regione Lombardia in the ambitious framework of river connectivity restoration of the water courses in Lombardy. With the inauguration of the Isola Serafini fish passage, the ecological corridor from Lake Lugano to Adriatic Sea will be totally viable to the fish: two fish passages on Ticino River and two on Tresa River (partially financed by Cantone Ticino) have been built within the previous years and both are waiting that this last intervention will finally restore a migration route precluded to the fish since the mid 50s. The barriers on Adda and Oglio River are and will be interested from this huge plan of defragmentation too, and during the next years we and our kids could hopefully admire the return of sturgeons, eels, mullets and twait shads in the areas where they have been missed since many years.
Life Project “Con.Flu.Po” website
