THE SEA-FISHERIES 303 



on the Dogger Bank, but only to 4J ounces on the inshore 

 grounds. 



" The cost of catching the small plaice and transporting 

 them to the feeding-grounds is not excessive if large numbers 

 are dealt with, and an experiment on a commercial scale 

 would, in the opinion of most fishery naturalists, be now 

 fully justified. It must be remembered, however, that for 

 all projects which aim at increasing the supply of marketable 

 fishes in the high seas international co-operation is almost 

 essential, as the grounds are open to all nations and all 

 would benefit by any improvement effected." 



Apart from these and many other experiments in practical 

 fisheries exploitation and cultivation — in which the United 

 States of America certainly led the way^modern fisheries 

 research is directed towards finding out the conditions 

 under which the food-fishes five, feed, migrate, and reproduce 

 their kind, so as to determine the possibilities and methods 

 of preserving them from destruction, increasing their 

 numbers, and even eventually of predicting when and where 

 profitable fisheries may take place. 



And, in regard to all these characteristics — feeding, 

 spawning, etc. — a special study has to be made of each 

 kind of fish. Many of them differ very notably. To take 

 an example of this from the spawning habits and the early 

 stages of life, the eggs of the herring are laid upon stones 

 and sea-weeds on the bottom of the sea in shallow water, 

 and there they remain undergoing their embryonic develop- 

 ment until the young herrings are hatched out ; but this is 

 quite exceptional amongst common edible fish. Most of 

 the others, such as the cod, the plaice, and all their relations, 

 produce eggs that float and remain near the surface of the 

 sea throughout their further development, as was discovered 

 in 1864 by Professor G. 0. Sars in the case of the cod. 



The various kinds of edible fish are caught, some by hooks 

 on long fines (such as the cod), some by trains or long lengths 

 of nets (the herring), and some by beam- or otter- trawls 



