Foreword 



In the struggle for existence that occupies the time of all successful 

 living tilings, there is constantly the pressure on the part of an organism 

 to increase its numbers, and the opposite pressure of competing organisms 

 to reduce its numbers. This is done unconsciously, as far as we know, by 

 all living things but man. Man, though, is so peculiarly endowed by nature 

 with reason, and tlie ability to think of the future and to plan for it, that 

 diis matter of changing the numbers of living things becomes an obsession 

 with him. 



Much of man's activity, either indirectly or directly, is aimed at manipu- 

 lating populations. He increases the numbers of wheat plants, and de- 

 creases the numbers of Hessian flies. He increases the numbers of sheep 

 and decreases the numbers of those organisms which parasitize sheep. He 

 increases the numbers of grouse or rabbits and then concerns himself 

 with the diseases which attack these game species. He wishes to increase 

 the numbers of lake trout and at the same time he searches for methods 

 to destroy the sea lamprey. 



From the beginning of time man has used other organisms in his 

 ascendency to his present state. Early expressions of culture which have 

 come down to us include arrow points and hammer heads for the capture 

 of game, and spears and hooks for the capture of fishes. 



In man's attempt to manipulate populations, the art of fish and game 

 management had its roots. But a new phenomenon has appeared within 

 the present century, and much of it after the first two decades had passed. 

 This has been the changing of the art of management to the science of 

 management. As we have learned more about fish and game, we have 

 found that these organisms often react in an empirical, predictable way, 

 and the old wives' tales and rules of thumb of just a little while ago have 

 been found to be erroneous unless they happened to be based on what 

 we now know as scientific fact. 



The knowledge which we have of a field such as fish management be- 

 comes so hidden in the literature, and sometimes so abstruse to the non- 

 speciahst, that it must be brought together and interpreted by someone 

 who is conversant with the field. This is what Dr. Bennett has done in his 

 book. 



