CHAPTER 3 



Distribution and Description 

 of Fisheries 



F. Heward Bell 



There are at least 40,000 species of fish and an even larger number of 

 other aquatic organisms, but, as with land plants and animals, few are 

 abundant and still fewer exist in concentrations to be harvested economi- 

 cally. This is indicated by the preponderant contribution made by a few 

 fish groups: herring-like fish (the sardines, anchovies, menhadens, sauries, 

 and herrings) and cod-like fish (the hakes, haddocks, and cods) constitute 

 40 percent of the present world catch of aquatic organisms. 



Aquatic organisms account for about 4 per cent of the world production 

 of food including allowances for the contribution of aquatic products to 

 land production. The generally quoted 10 per cent contribution of aquatic 

 products to the world's protein supply is probably high if due regard were 

 given to the essential amino acid contribution of vegetable and animal 

 proteins. 



Life Conditions in the Sea 



The food chain of the sea starts with small surface plants or phyto- 

 plankton which through photosynthesis use solar energy to build organic 

 tissues from dissolved inorganic components. This occurs only in the 

 light-penetrable surface layers. The sinking of the dead plankton rapidly 

 depletes the nutrients of the surface. However, the bottom, enriched by 



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