116 THE FISHING INDUSTRY 



(2) The shellfish may be diseased, or be seriously 

 contaminated, by living in dirty water. 



(3) Decomposition may set in after the shellfish have 

 been removed from the water particularly if they have 

 been kept too long in a warm place. 



It has been found recently that shellfish that have 

 been deliberately fattened on sewage can be effectively 

 cleansed in such a way as to get rid of ingested sewage 

 bacteria. This process has been carried out success- 

 fully on a commercial scale at Conway by the Ministry 

 of Agriculture and Fisheries. Danger from infected 

 shellfish may also be safely avoided by boiling them. 

 When shellfish are gathered at the right season of the 

 year and from suitable localities, they are a perfectly 

 safe and wholesome food. 



Of the many species of edible fishes that are known 

 and used, the number is by no means complete, and new 

 species are added from time to time. Thus, in 1916, 

 the United States Bureau of Fisheries introduced a new 

 edible fish (Lopholatilus chamaeleonticeps), which they 

 christened the tile fish. After this fishery had been in 

 existence for twelve months, the known catch of tile 

 fish amounted to over 10,000,000 Ibs., valued at more 

 than $400,000. In 1917, the same Bureau introduced 

 the dog-fish under a new name. As people were 

 prejudiced against the name " dog fish," the Bureau 

 altered it to " gray fish," " which is descriptive, not 

 preoccupied, and altogether unobjectionable." The 

 fish is now caught in large numbers, and forms the basis 

 of a very flourishing canning industry. Attempts have 

 been made recently to utilize as food the edible portions 

 of the shark (which is closely related to the dog fish) 

 and the porpoise. 



The food value of most fishes varies very much 

 according to the condition of the fish when it is caught 



