33 



fair quantity of bass (Lad rax /uftus), soles and plaice also 

 enter together with various crustaceans and molluscs. 

 The young eels at the time when they enter estuaries 

 are 6 to 7 centimetres in length and it is estimated that 

 some 3,600 individuals go to a kilogram. The mullet 

 fry are still smaller, 20,000 going to the kilo. The 

 former attain maturity only after a residence of 4 to 5 

 years in the ponds when they should weigh from 4 to 

 5 lbs. each. During the period of ascent, February, 

 March, and April, care is taken to prevent net-fishing off- 

 the coast in the neighbourhood of the lao-oon, but after 

 the closing of the lagoon at the end of April or the 

 beginning of May, a large quantity of young mullet are 

 caucrht bv means of fine-meshed nets in the shallows 

 along the coast ; this particular stock is kept separate 

 from the general herd, being placed in special ponds. 



When the inward migration of the young fishes 

 diminishes to inconsiderable proportions, usually about 

 the close of April, measures are taken to close all means 

 of egress from the lagoon. The river sluices are shut, 

 the gaps in the embankments are repaired and the 

 mouths of the permanent passages leading from each 

 valle to the adjoining sea-canal are closed by the con- 

 struction of palisades of stakes, to which are bound 

 tightly packed bundles of reeds, planted upright in the 

 mud. These particular obstructions are termed tresse ; 

 they occupy a most important position in the working 

 of a valle, for while they must be capable of impeding 

 the escape of fish to the sea, they must allow tidal 

 water to enter the otherwise closed ponds — a difficult 

 proposition. 



The openings closed by tressa-palisadings are re- 

 stricted to those centres known as fishing stations where 

 permanent passages are maintained either between each 

 valle and one of the sea-canals or between adjacent valli. 

 In general each valle has one fishery station, but some 

 have more. Mezzano has 4, Campo and Ussanola 3, 

 Cona has 4, Vacca has 2. From each of these stations, 

 branch out towards the particular valle served, a number 

 of short canals called Covole (text-figures 4 and 7) which 

 have the function of reducing the tidal Mow received 

 from the main and wider sea-canal by dividing it into a 

 number of smaller streams and thus discharging it into 



