V. Outlook for the Future 



Effective management of fisheries resources of the 

 open ocean presents a great challenge that can be met by 

 well-planned, year-round observations conducted without 

 interruption for a number of years. The m.ost important 

 scientific phase of this research is concerned with the causes 

 of the great fluctuations in the abundance of fish stocks. For 

 the past hundred or more years these fluctuations have 

 greatly affected the fishing industries of this country and in 

 Europe. Frequently the cause was attributed to one or another 

 factor--such as overfishing, changes in ocean currents, or 

 temperature deviations from the expected average--without 

 actually ascertaining all the complicated interrelationships 

 between the welfare of a fish population, environmental 

 changes, and the effects of man's activities. The intricate 

 picture of life in the open ocean cannot be elucidated by a 

 single short-term observation in a restricted area. The 

 census of fish populations should be taken from year to year 

 together with measurements of changes that may occur in 

 the oceanic environment, particularly in climate and weather, 

 observing the pattern of currents, and determining the 

 abundance of the food supply for different species. Life in 

 the ocean does not remain stable. Contrarily, it is in a state 

 of unstable equilibrium in which the struggle for existence 

 gives temporary predominance to one group which in turn 

 may be replaced by another. For an understanding of such 

 interactions, long- continued and well-planned observations 

 are needed. 



An evaluation of the events that take place among 

 free-living and rapidly moving marine populations cannot 

 be made by studying a single species of commercially 

 important fish. All species of fish compete for space and 

 food and are directly or indirectly dependent on the abundance 

 of zooplankton and bottom organisms which in turn are controlled 

 by the abundance of microscopic plants and bacteria. In final 

 analysis the entire food chain in the ocean from mineral salts, 

 necessary for microscopic plants, to the abundance of the giants 

 of the sea--sharks, tunas, and whales- -depends on sun energy 

 absorbed by the surface of the ocean. Therefore, it is clear 

 that biological observations on a marine population must be 

 based on detailed oceanographic studies. The needs and tolerances 

 of various species for temperature, salinity, oxygen, and food 

 must be known in order to interpret possible effects of slight 

 changes in the environment. To this long array of particulars 

 must be added the study of the behavior of fish, and diseases 

 which sometimes decimate the entire population. This type of 

 work requires the facilities of a modern laboratory and 



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