4 2 



added to the fishery system in the middle of the 17th 

 century ; at no time however can this lagoon system 

 have been immune since the period when it ceased to be 

 a lag una viva — one wherein the sea daily ebbed and 

 flowed freely throughout its whole extent. Blizzards 

 from the Alps, exceptional floods in the rivers bounding 

 the lagoon, intensely hot and dry summers — these are 

 the three factors which are recognized as the principal 

 causes of seasons of failure. For example, in 171 1 

 a tempest of such intensely cold wind descended upon 

 the lagoon that the fish died in myriads. This followed 

 upon other losses in 1705 and 1709 caused by flood 

 irruption of the adjoining rivers, whereby the dykes and 

 tresse were submerged, allowing a great proportion of 

 the imprisoned fish, young as well as mature, to escape 

 to the sea. 



Again, in the years 1 7 1 8 and 1 7 1 9 the heats of summer 

 were so intense and long-continued that a great portion 

 of the lagoon dried up and immense deposits of salt 

 formed upon the bottom. Bonaveri states {loc. cit.) that 

 salt to a value of over 18,000 scudi was collected. 

 Owing to the immense amount of evaporation in these 

 years the water that remained in the deeper sections 

 became so highly saline that widespread mortality 

 resulted amono- the fishes. 



These disasters were exactly paralleled in the course 

 of last century. In 1825, 1834, 1890, 1 891, the summers 

 were abnormally warm and as a result of active evapora- 

 tion over the 40,000 hectares of shallow ponds the 

 resultant high salinity of the water entailed enormous 

 loss among all ages and species of the fish in most of 

 of the ponds in the lagoon. In 1890 the seaward flight 

 of the fish into the labyrinths was a veritable stampede 

 and disastrous in proportion. The catch surpassed a 

 million kilogrammes (say, 1,000 tons) in great part com- 

 posed of minute and immature fish such as required a 

 sojourn of several years longer in the ponds to attain a 

 proper size. In the pounds of a single valle, that of 

 Vacca, 100,000 kilos of fish were taken, while Valle 

 Fossadiporto gave half this quantity within a few days. 

 Much of the fish taken in the labyrinths was so tiny 

 that the greater part after being placed in the great 

 wicker store-baskets passed easily through the interstices 

 and so escaped to the sea. 



