CHAPTER IV 



CONSIDERATION OF INDIVIDUAL FISH (THE PLAICE, SOLE, 

 HADDOCK AND HERRING) 



THE PLAICE (as a type of flat-fish) 



THE two most important families of demersal fish in 

 Northern European waters are the Pleuronectidse (plaice 

 family), and the Gadidse (cod family), of which latter the 

 •iiaddock is a member. Without these two families steam trawling 

 would speedily collapse. The former family, the plaice, comprises 

 species which are for the most part sedentary, and may therefore 

 be susceptible of permanent and serious diminution as the result 

 of overfishing. The haddock is believed to be less sedentary than 

 the plaice. As a means of solving problems connected with the 

 questions of overfishing, the study of species like the plaice and 

 haddock is of importance. With the exception of the herring, 

 the plaice has been the subject of more controversy than any other 

 species of marine fish. Within the last few years considerable 

 attention has been devoted to the study of this fish and the results 

 of the various investigations are not without interest, though the 

 task of wading through the mUe-long colunms of statistics is Sisy- 

 phean. 



The plaice {Pleuronectes platessa, L.) is probably the best known 

 member of the flat-fish family. This family is characterised by 

 three easily recognised peculiarities ; both eyes are on one side of 

 the body, the eyed surface is coloured, the other side being white ; 

 the dorsal fin extends forwards as far as, or even beyond, the eyes, 

 running along the edge of the head, not between the eyes. 



Seven genera and fourteen species of Pleuronectids are known to 

 inhabit British seas. Of non-British genera and species, several are 

 now accessible to British markets, being captured by steam trawlers 

 in Portuguese and Moroccan waters, for example, " soles " of the 

 genera Synaptura and Cynoglossus. 



Of the genus Pleuronectes there are five British species, namely 

 Pleuronectes platessa (the plaice), P limanda (the dab), P. flesus 

 (the flounder), P. cynoglossus (the witch) and P. microcephalus (the 



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