-«Sp" 



Because the breeding grounds of the fur 

 seal have long been known, the animals 

 have long been subject to slaughter by the 

 sealers v^ho indiscriminately killed nursing 

 mothers and pups. Deprived of its mother, 

 a pup (the one shown here is two weeks old) 

 cannot fend for itself and may perish. 



from the herring fisheries. Their fortunes declined some-what when, 

 in the fifteenth century, the local herrings altered course to run 

 down the coast of Holland instead of along the German coasts-. But 

 there were other, and more important reasons for the decline. 

 During the fifteenth century there were improvements in offshore 

 fishing boats and in methods of preserving herring. This enabled 

 Dutch fisheries — and later EngHsh fisheries — to compete with the 

 Hanseatic inshore fisheries; hence to a large extent the decline was 

 a relative one. 



Modern science is increasingly interested in conserving the 

 supply of fishes. Man's inroads when harvesting the sea have led to 

 the need for vast programs of research into new methods of con- 

 serving the world's fisheries. In the closing years of the nineteenth 

 century an idea was born - an idea that was to make possible a 

 working co-operation between scientist and fisherman the world 

 over. 



The hope was that there might be a way to judge the age of 

 fishes by the markings on their scales. A widespread study of this 

 concept has made it possible for modern man to apply the principle 

 of age determination to all marketable fish. At first biologists dis- 

 covered a linkage between the size of herring and the number of 

 rings on their scales. Then a Norwegian, Einer Lea, did some 

 pioneer research on the scales themselves. He and his followers 

 studied them minutely, split them into layers for an examination 

 of their internal structure, cut them into thin sections, and examined 

 them microscopically until it was established beyond doubt that 

 there is a definite relationship between the growth of a scale and 

 the growth of the fish. 



The annual rings on the herring proved trustworthy, as did 

 those of some other food fishes, such as the salmon. In others the 

 scales proved unreliable for a variety of reasons. But it was found 

 that the otoliths - small calcareous concretions in the ears — serve 

 as well, since they also show annual rings. Age determination by the 

 otoliths is now used extensively for such fishes as plaice. 



This work ushered in an age of scientific management of the 

 world's fisheries, first in Europe, then elsewhere. For a long time, 

 however, many thoughtful men had realized that something must be 

 done to maintain the dwindling supply of food fishes. One of the 

 chief causes of depletion in the stocks of the ocean's food fishes has 

 been the destruction of small fishes, which are taken from the sea 

 before their time and are thus prevented from breeding. The work 

 on age determination is vitally important in dealing with this 

 problem, and so is the work that has been done on determining 

 the best nets, sizes of mesh, and fishing seasons. 



Although the most familiar crops of the sea are fish, there are 

 other important harvests, among them seals; and it is from the 

 sealing industry that we have learned an important lesson in con- 

 servation. With the exception of the Alaskan fur seal, the score or 

 more of different kinds of seals are far less numerous today than 

 they used to be. In all parts of the world they have been severely 

 reduced in numbers, and in some places, as with the West Indian 

 monk seal, they have been brought to the brink of extinction. 



This happens to any group of animals for one of two reasons, 

 or both: Either the animals are a nuisance to man or they are of 

 great use. Seals have suffered persecution, especially in modern 



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