A REVIEW OF THE LIFESPANS AND 



MORTALITY RATES OF FISH IN NATURE, 



AND THEIR RELATION TO GROWTH AND 



OTHER PHYSIOLOGICAL CHARACTERISTICS 



R. J. H. Beverton and S. J. Holt 



Ministry of Agriculture, Fisheries and Food, Fisheries Laboratory, 

 Lowestoft; and Fisheries Biology Branch, F.A.O., Rome 



Studies on the dynamics of fish populations have received 

 a major impetus in recent years owing to the need to provide 

 an adequate scientific basis for conservation. One aspect of 

 these studies is the measurement of fish longevity and the 

 force of natural mortality in fish populations. In this contri- 

 bution we attempt to review the present state of knowledge 

 on these questions. 



In so doing we have two objectives in mind. One is to 

 present the data on longevity and mortality in fish for com- 

 parison with what is known for other animals and presented 

 at this symposium; the other is to see to what extent these 

 characteristics are, in fish, associated with size, growth, 

 maturation and certain other physiological factors for which 

 data are available. 



It has not been possible for us to search through the widely 

 scattered literature as thoroughly as we would have wished. 

 The paper is therefore perhaps best regarded as a progress 

 report from which certain tentative conclusions can be drawn 

 at this stage. 



Natural mortality and lifespan 



Many of the fish populations which have been intensively 

 studied are those supporting a major commercial fishery and 

 are therefore ones in which the effect of fishing has profoundly 



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