180 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



to poles and Iragmeuts fouud at the bottom of the water, so that every 

 available surface is soon covered with diminutive oysters, which in a few 

 months have reached a considerable size, and have a very fine flavor. 

 Shell-fish culture in the estuary, from reasons more or less well known, 

 is at i)resent in a state of decline. 



There are iy our waters two kinds of oysters : the sea oyster and the 

 la},^oon oyster, there being two varieties of the latter kind, namely, the 

 marsh oyster and the canal oyster. The sea oysters equal the lagoon 

 oysters in size, but do not have so fine a flavor, as owing to the difierent 

 food they have a somewhat sharp taste, described in the vernacular of 

 the district by the term '■'- marinazzo'''' (flavoring of the sea), which is not 

 pleasant to epicures. This kind is at the i)resent time fouud in the sea 

 in considerable quantities, and also forms more or less extensive beds, 

 which, however, have been almost exhausted by the fishermen, owing 

 to the great demand for oysters. 



Among the lagoon oysters the most highly esteemed are those taken 

 in swamps which are not very deep. They have a jjleasant flavor, a dark- 

 green color, and equal in price the best oysters known. These mollusks . 

 ibund in the estuaries generally live isolated, and at any early age usu- 

 ally become fixed to some little shell' of Cardium, Venus, Trochus, Murex. 

 Cerithimn, &c., which, when the oyster is taken from the water, will 

 always be attached to the lower shell near its ai)ex. For a time this 

 oyster was very common throughout the entire lagoon, both in running 

 and stagnant water, but now it has become less frequent, and, in fact, 

 has almost disappeared from the greater jiortion of these marshes. 



The threatened destruction of our best mollusks is i)robal)ly caused 

 by the influx of fresh water in the lagoon, and chiefly by the tracts of 

 cultivated ground which bring about conditions which are hurtful to 

 the life of the oyster and other shell-fish. It seems that similar causes 

 have made the oysters become scarce in other i)arts of Italy. 



This hurtful influence has also extended very rapidly to the lagoon 

 with running water, doing serious injury to the ojster grounds nearest 

 to the mouth of the port, in which during the last few ye-vrs young sea 

 oysters have been scattered, which after a certain time had reached the 

 size and acquired the flavor wliich is demanded in the markets, without, 

 however, equaling in flavor those raised in the marshes. 



This condition of aflairs caused several attempts to restock these 

 marshes, among which there deserve to be speciallj* noticed those made 

 by Chevalier D'Erco, who, not being acquainted with our peculiar hydro- 

 graphic conditions, attempted to pursue in the estuary of Venice the 

 metlujd of oyster culture employed in the Bay of Arcachon and along 

 the coasts of France and Belgium. The reservoirs {claircs) of D'Erco 

 constructed along the canal of Sant' Antonio, near Burano, which 1 

 visited several times, proved a failure, as practical men had predicted, 

 as neither the oysters nor the mussels could bear the heat of the sun, 

 which heightened the teiiiperature of the inclosed water and increased 



