If the sea is to be exploited as fully as possible^, an attempt 

 must be made to retain the stock at optimum strengtho A dense^ very 

 large stock is very profitable for the individual fisherman because 

 he will be able to take large catches within a short timeo However^ 

 the total productive power of a very dense stock is rather lowo 

 Nevertheless^ there seems to be little possibility that any access= 

 ible sea will be fished with too low an intensityo The demand for 

 fish and the chance to make a good income will increase the fishing 

 intensity quickly and, if no regulations are made, the strength 

 of the fish stock will soon decline below the values corresponding 

 with the optimum catcho Then, since the fishermen will not be 

 willing to take smaller catches, the fishing intensity will be 

 increased to the point where, in addition to the annual increase 

 of the stocks, part of the stock itself will be taken© The stock 

 will then decline with an increasing rateo As soon as the point 

 of optimum (maximum allowable) catch has been reached, a further 

 increase of the fishing intensity will only lead to a decrease of 

 the total catches o The state of overfishing has appear ed and that 

 is the state whereby more than the optimum catch is taken from " 



the fish stock o 



More than 30 years of intensive international scientific 

 cooperation has been necessary to develop this theory of the ratio 

 between fishing and productive power© 



To increase the readability of this paper, several investigators 

 are not mentioned in the texto However, it may be said that Russell 

 (1931) began to analyze the factors which regulated the productive 

 power of the fish stock and that Hjort and associates (1933) were 

 the first to develop the idea of the optimum catcho The theory was 

 further developed by Graham (1935, 1938, 1939, 1944), by Buckmann 

 (1938) and by Russell (1939) o In the meantime, Thompson (1934, 1937) 

 showed from a study of the halibut in the northeast Pacific Ocean 

 that decreasing of fishing intensity may lead to an increase of the 

 total catcho 



The task is now to find the fishing intensity which, for a given 

 area, corresponds with the optimum productivity of the fish stocko 

 For an area which has been fished for years with changing intensity, 

 the optimum catch and the accessory fishing intensity can be found 

 from the fishing statistics o 



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