ECONOMICS OF THE FISHERIES 315 



(Jordan, Evermann and Clark, 1930) lists 4,137 species and subspecies of 

 finfishes (fresh and salt water). We have seen no list of all the species 

 in the world, nor any estimate of their number; we might surmise the total 

 number to be 12,000 or perhaps many more. A correspondingly large number 

 of mollusks and Crustacea must be included to cover all of the fisheries. 



Man has found use for, and catches practically everything of the range of 

 one-half pound in size and up, that is sufficiently abundant to be worth while, 

 and many of smaller size, such as shrimps, oysters, clams, sardines, smelts, 

 and whitebait. Some, such as jellyfishes, sculpins, sting rays, conchs, star- 

 fishes, would be used if sufficiently abundant to be caught at low enough cost 

 for the purpose for which they have a value, and new uses are being found 

 from time to time. Sharks, which until a few years ago were not used, are 

 now the basis of a major fishery as sources of vitamins, and to some extent 

 for leather. There seem to be no useless fishes, though some are not used. 

 The total number of commercial species in the world might be a thousand or 

 even more. The great bulk of the commercial catch of fish throughout the 

 world is in five families (each having numerous genera and species as mem- 

 bers), viz., the herrings (about 45 per cent of all), codfishes, salmons, flat- 

 fishes, and mackerels. If we add two or three species of oysters and a dozen 

 shrimps, with the sharks and rosefish coming into some prominence in recent 

 years, we have the bulk of the world's production of fish and shellfish. 



Of the 4100-odd species in and around North America, the U. S. Fish & 

 Wildlife Service lists from year to year close to 200 commercial varieties or 

 "species," some of them consisting of two or more true biological species; 

 the total number including minor species used might be 500 or more. The 

 fluctuations in quantity of any one species, even the most important, makes 

 hardly a significant difference in the whole fishery. Many of these species 

 are subdivided into trade classifications not shown in the statistics; buck 

 and roe shad, silver and yellow eels, white and gray halibut, several size 

 grades each of cod, haddock, halibut, whiting, mackerel, oysters, clams, 

 shrimps, etc. In variety, the number of species of seafoods in this country 

 approaches if it does not exceed the total number of species of all other foods 

 both vegetable and animal used by man. This fact of diversity of kinds and 

 sizes of fish touches every aspect of the economics of production and market- 

 ing, and as a determinant is second in importance only to the non-private 

 ownership of the source. 



Movements and Geographical Distribution of Fish. Each species has its 

 characteristic geographical range, usually within temperature and depth 

 limits; some are sedentary, others migratory; some spawn at sea, others come 

 inshore or into sounds and bays or enter fresh water streams or otherwise 

 become accessible at some particular season and not to be found at other 



