Extensive brackish-water fish farming in the Italian "Valli de pesca"
Boatto, V.; Bonotto, G.; Breber, P.; Penzo, G.; Strada, R. (1989). Extensive brackish-water fish farming in the Italian "Valli de pesca", in: De Pauw, N. et al. (Ed.) Aquaculture: a biotechnology in progress: volume 1. pp. 111-118 In: De Pauw, N. et al. (1989). Aquaculture: a biotechnology in progress: volume 1. European Aquaculture Society: Bredene. ISBN 90-71625-03-6. 1-592 pp., more |
| Available in | Authors | | Document type: Conference paper
|
| Authors | | Top | - Boatto, V.
- Bonotto, G.
- Breber, P.
| | |
| Abstract | The "valle da pesca" is a method for extensive polyculture of fish developed over the centuries in the lagoons bordering the northern Adriatic coast of Italy. There are over 50 "valli" covering in all about 30 000ha. A typical enterprise manages ca 300ha of water enclosed by a dike, originally a portion of lagoon shallows. By operating a series of water gates in the dike at different stages of the tide, the necessary exchange of water can be obtained. B0th salt-and freshwater should be available on command. Besides the dike, other artifacts include the headquarters building, enclosures for the fry and for the overwintering of the fish, a large sluice with fish weirs at the main water gate, and a series of underwater canals. Most of the "valle" consists in a highly productive natural environment used as fish pasture. The water depth is about 0.5m, the substrate consists of silt, the temperature ranges trom 6 to 29°C, and the salinity from 20 to 35°/oo. The Characterising species of the ecosystem are Zostera nana, Cerastoderma glaucum, and Atherina mochon. The cultured fish species are Sparus aurata, Dicentrarchus labrax, Anguilla anguilla, Mugil cephalus, M. chelo, M. saliens, M. auratus, and M. capito. Stocking is done with fry only a few months old and with elvers. The eels reach a marketable size in 8 years, M. cephalus and M. chelo in 5 years, sea bass and the mullet in 3 years, and sea bream in 2 years. The recovery is 40-85% with sea bream, 15-50% with sea bass, 3-40% with mullet, and 6-30% with eel. The fish are caught by enticing them into weirs by a flow of water let in from the main water gate. The average yield of a "valle" is 95 kg.ha-1 of which 36% are mullets, 29% sea bream, 17% sea bass, 15% eel, and 3% Atherina mochon. The "valle" ceases to be profitable if the yield falls below 92kg.ha-1. |
|
