THE SHELLFISH INDUSTRY 303 



Belgium, and Denmark, while in Norway they are grown 

 in special " oyster pools " at the heads of many of the 

 fjords. These pools, which are natural, are almost com- 

 pletely cut off from the water in the fjords, and as a result, 

 they become extremely warm in the summer, the micro- 

 scopic plant life increases just as it does in the claires, and 

 the oysters, which are usually kept in floating cages near 

 the surface, grow at an unusual speed. Oysters have been 

 cultivated for several centuries in Japan, where spat is 

 collected, not on tiles, but on an ancient and efficient 

 type of collector consisting of short lengths of bamboo 

 on which the branches are left and which are stuck into 

 the ground between the tide marks. The young oysters 

 are left on the bamboos for from one to two years when they 

 are detached and spread on prepared beds which are seldom 

 uncovered except in spring tides. No artificial tanks are 

 required and the process of cultivation is simpler than that 

 adopted in Europe. In many regions along the coasts 

 of the United States there are important oyster beds, some 

 of which are in deep water and are fished by powerful 

 steamers, capable of dredging immense numbers of oysters — 

 up to 1,800 bushels per day. In Australia also oysters are 

 cultivated, especially in New South Wales where spat is 

 collected on stones, or on mangrove sticks which are stuck 

 upright in the water. The oyster may then be matured, 

 either laid on beds composed of shell or gravel, or else i^ 

 wire netting trays. 



Other Molluscs 



After the oyster, the common mussel [Mytilus edulis) 

 is the most important molluscan shellfish used as food in 

 Europe. It is so common as to need no description. It 

 is very abundant in sheltered parts of the coast, or in the 

 mouths of rivers along the coasts of Britain. The natural 



