Valle da Pesca

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A Valle da pesca is a demarcated water area within the Venice lagoon . These areas are separated from the open lagoon by reeds, rows of stakes or dams and thus enable a special form of intensive fish culture. In total, the valleys in the Venetian lagoon cover an area of ​​92 km², with some valleys only covering a few hundred square meters, the largest being more than 1,600 hectares. They are predominantly located on the edges of the lagoon, especially on the north and on the north Southwest edge.

Board at the Rialto fish market stating the minimum size of fish

The name goes back to the Latin word vallum , but does not mean either the modern word for 'lagoon' or that for 'valley', but rather 'protection', 'wall' or 'wall'.

The managed valli include the Val Dogà in the north of the lagoon, the largest valley with 1685 hectares, then Grassabò, Dragojesolo, Cavallino, Lio Maggiore, Liona and Perini. In the southern lagoon these are the Valli Serraglia, Averto (which is partly protected by the World Wildlife Fund ), then Contarina, Zappa, Figheri, Pierimpié, Morosina and Millecampi .

history

The reproductive zone of most of the fish in the lagoon is in the Adriatic Sea , only the young migrate into the lagoon. The nutrient richness contributes to this, but also the small number of predators compared to the open sea. The observation of this annual immigration and emigration presumably prompted the people early on to stop the emigration of a certain part of the animals and to fish them. The Valli probably existed before Venice was founded .

The Valli, which are extremely productive for fishing and breeding, were early in the hands of less noble families or monasteries. The sources show this from the 11th century at the latest. Most of the lease contracts were extended annually. However, most of the Valli were in the hands of the same families for decades.

The contracts of the Republic of Venice provided the tenants with numerous obligations that served to preserve the fishing areas. So ramparts or ditches had to be built or repaired, for the maintenance of which the Vallesani , the tenants, received compensation. For the republic , the ability to meet part of its food needs through hunting and fishing meant greater security against rapidly rising prices or even hunger. In addition, the preservation of the Valli ensured the protection of the natural environment, which offered numerous birds opportunities to live. These were hunted by the urban nobility.

Since the Middle Ages , the borders of the Valli have consisted of mobile reeds, the grisole . Until its dissolution in 1797, the Republic of Venice prohibited the establishment of solid, permanent networks or dams so that the waves of the water (marea) could spread freely. Since this was changed, juvenile fish have to be brought in from the Adriatic and released.

The legislation dealt with the Valli da pesca from 1314 . In 1719 the responsible magistrate had all Acque 100 markings set to fix the boundaries. It must be taken into account that the wealthy families who owned the Valli were mainly interested in hunting and less in fishing. Initially there were two types of Valli, namely the Valli a seragia , whose water level was the same as that of the rest of the lagoon, and the Valli ad argine . Their water level was artificially increased with the help of dams, lock systems, gate valves ( porte a saracinesca ).

The Serenissima was well aware of the vulnerability of the Valli, and so it entrusted its management exclusively to those who fish there. From 1624 they were no longer accessible to the public.

The process of privatization and closure of the Valli began between the early 19th and 20th centuries, such as was practiced in the Pierimpié Valley. This development was accelerated from the 1950s. Now men, called pescenovellanti , had to be employed to fish the young . This activity became one of the most important occupations of the men from Burano , Caorle , Cortellazzo , Pellestrina and Chioggia in the 19th century . They were busy with it from the second half of March to mid-June. The fishermen in the Valle di Comacchio, in turn, specialized in creating fixed boundaries for the Valli and in eel farming .

Structures

The Chiaviche , sluice-like structures that mainly date from the 19th century, made it possible to regulate the water flows by hand. In particular, they allowed the salt content to be regulated in order to offer the fish that were to be drawn there an optimal habitat. They are mainly located within the Valli to regulate the currents there, but also at their edges to control the exchange of water with the lagoon. The latter are in the neighborhood of the Casoni di pesca . The canals are found on natural structures, winding through the valleys, as well as artificial, mostly straight canals. The so-called lavorieri are a type of fish traps in which the fish are caught in a two-part, vertical wickerwork that tapers at an acute angle ( cogolere ). Animals that have not yet reached the size to be allowed to be sold on the market are brought to their own, braided areas over the winter. These are of the greatest importance as most fish take two or three years to reach the market, and eels even eight years later. To protect them against the sensitive cold winter winds, French tamarisks were used until a few years ago , which also provide a habitat for purple herons . In the meantime, mostly artificial networks are used. In addition, these areas have to be quite deep to protect the fish from freezing through the water. For this purpose, fresh water is slowly directed onto the existing water in order to freeze it on the surface.

The only houses are the structures known as Casoni di pesca . From there the management of the Valli was controlled. In addition to these mostly large houses from the 19th century, which have since fallen into disrepair, there are storage facilities for equipment and tools, cooling systems and the protected boat moorings known as Cavane . Other buildings are only intended for hunting, the botti da caccia .

Work in the Valli begins in spring. The juvenile fish are released into the main tank or caught in the sea. The latter is called pesca del pesse novelo . The Valli only reaches a very small proportion with the natural currents. The pesse novelo , the young fish, first arrive in the seragio del pesse novelo , a protected area where they can get used to the new conditions for two to three months. The salt content there must be controlled very precisely, as well as the mixing with oxygen . When the fish are big enough, they are led through locks ( chiaviche ) into the actual valley .

In a fixed cycle, the fish are gradually guided through different parts of the valley. Towards the end of autumn, the fish are made to swim towards the sea by adding cold water. The fish prefer the warmer sea water; that is also where reproduction takes place. Some of the fish are fished and sent to the markets or brought to winter using the method described.

fauna

The main fish represented are eels , mullets , sea ​​bass and sea bream . They can tolerate large fluctuations in salinity.

The Valli also offer a large number of ducks , but also other bird species that winter here coming from the north, as well as fixed birds, mammals and reptiles suitable habitats.

In addition to the mallard, species such as the marsh harrier or the pond rail , the coot , the Kentish plover , the common tern , the bag tit , the purple heron and the night heron , the redshank and the great crested grebe can be found in stationary birds . The great crested grebe and the black-necked grebe appear as migratory birds , but also the great egret , as well as various ducks.

Mammals include mouse species such as the harvest mouse , the water shrew , as well as the European polecat , the stone marten , the large vole , the weasel or the brown-breasted hedgehog .

In addition, there are the yellow-green angry snake , the grass snake and the dice snake .

There are also numerous species of insects and spiders.

flora

The flora differs only slightly from that of the barene , the local salt marshes . Numerous species from the species of samphire , sea ​​lavender and salt plumes can be found here .

The vegetation below the water level is of two communities of seed plants formed which are for the ducks is of great importance, namely the seagrasses counting dwarf eelgrass and the balances on counting marine Salde that are lower especially in areas salt concentration finds stable ground.

In the freshwater areas there are reeds , which can also tolerate low salt concentrations. The cattail , especially the broad-leaved species , lives where there is only fresh water .

The importance of the Valli for the lagoon is, among other things, that they replaced the ecological niche that once prevailed in the swamps ( paludi ) and in the acquitrini to a certain extent, as these older forms of lagunar life were largely destroyed. However, the lagoon as a whole benefits little from this, as the Valli are largely sealed off from the lagoon. That is why the partial opening of the Valli has been discussed for several years.

literature

  • Guido Alpa, Francesco Di Giovanni, Bernhard Eccher, Mario Esposito, Natalino Irti, Berardino Libonati, Giuseppe Morbidelli: Lo stato giuridico delle valli da pesca della laguna di Venezia , Wolters Kluwer Italia, 2010.

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