24 THE FISHING INDUSTRY 



Turbot not very abundant. It inhabits the deeper 



parts of the North Sea. 



Brill inhabits southern waters, and is fairly 



abundant. 



(c) The Raildac. 

 Skates and rays found all round Britain, more 



particularly the Western area of the English 



channel. 



(2) The various species of fish that inhabit the surface 

 waters of the sea are called " pelagic." They include 

 the herring, mackerel, tunny, flying fish, sword fish, and 

 many sharks, also various marine mammals, such as 

 whales, grampuses, porpoises, dolphins. Amongst pelagic 

 fish are included some of the smallest (plankton) as 

 well as some of the largest (whales) of all living creatures. 

 Pelagic fish pass their whole life swimming at or near the 

 surface. They enter the shallow water offshore only for 

 prey or, in some cases, periodically to spawn. The 

 majority spawn in the open sea, far from land. Unlike 

 demersal fishes, the distribution of the different species 

 of pelagic fishes depends very much upon local con- 

 ditions of light, water temperature, and the character 

 and quantity of food available. They do not hunt 

 their food individually to the same extent as demersal 

 fishes, but generally filter it from the water as it passes 

 through their gill-openings. Although not so widely 

 dispersed as demersal fish, they are, in favourable 

 circumstances, dispersed over large areas by swimming 

 and by ocean currents. 



All pelagic fish are " round." With the exception 

 of the mackerel, the important edible pelagic fishes 

 belong to the herring family, and are known as the 

 Clupeidae. They include 



Herring found from the White Sea to the Bay of 



Biscay. It is the most abundant of all food fishes. 



