598 SCIENCE PROGRESS 



the prevailing size of the plaice to be found in the different 

 zones and regions. The persistent fishing experiments of the 

 exploring steamers have also enabled us to determine the limits 

 of the areas where there is to be found a characteristic small 

 plaice population : such areas are to be regarded as nurseries, 

 from which the adjoining parts of the deep-sea area are recruited. 

 But the further study of these small-fish areas has also shown 

 that there is a definite relation between the prevailing size of 

 plaice on a ground and the abundance of the fishes there, and, 

 generally speaking, a small-fish area where the plaice are extra- 

 ordinarily numerous is also an area where the fish are dwarfed 

 and are smaller, and grow much more slowly, than in such 

 regions where the density of the population is less. 



A very great deal of the work of the international fishery 

 staff has been of the nature of a survey of the fishing grounds 

 of the seas of North Europe, made from different points of view. 

 Thus the English and the Dutch have very largely concentrated 

 their attention on the study of the distribution of the plaice, with 

 results which I have just indicated above. The Norwegians 

 have devoted some considerable attention to the cod fishery, 

 which is the fishery in that country, just as the fishery for the 

 herring is the predominant form of the industry in Scotland. 

 The great cod fisheries round the Lofoten Islands on the coasts 

 of Norway have been studied with particular care. Annually in 

 the spring the cod shoals invade this area to deposit their eggs 

 on the shallow sea bottom surrounding the islands and banks, 

 and it is at this period that enormous numbers of the fishes are 

 captured by the Norwegian fishing-boats. The fate of the eggs 

 resulting from this spring spawning has been studied by utilising 

 the Norwegian exploring steamer. For a limited period the 

 eggs are to be found on the surface of the sea, just where 

 the adult spawning fishes are most abundant at the bottom. 

 Then the developing eggs drift slowly to the west and north 

 under the influence of the prevailing current of water which 

 sets in that direction. As the eggs drift to sea they undergo 

 embryonic development, and after a certain time, according to 

 the temperature of the sea, the little fishes hatch out and begin 

 their pelagic career. As we pass outwards from the focus of 

 distribution, the larvae resulting from the hatching of the eggs 

 become larger, and there are definite zones which have been 

 mapped out by the Norwegian naturalists, each of which is 



