38o GENERAL DISCUSSION 



attained, they must be separated. We should certainly define 'regulation' 

 first, and then see if 'self-regulation' exists. 



I. A. McLaren : The connotation in 'self implies a behavioural system. 

 Regulation is usually thought of as an environmental effect. 



M. E. Solomon: It seems generally assumed that regulation is the 

 control of numbers by means of some type of feed-back system. As numbers 

 rise, this mechanism bears on the population more heavily. Self-regulation 

 is generally used as convenient shorthand, and if it is to be used more 

 seriously it needs careful defmition. Logically, it involves the fallacy of 

 abstracting the population from the environment. Even intraspecific com- 

 petitition always results from a limited supply of something in the environ- 

 ment. 



D. H. Chitty: Surely it is conceded that a self-regulatory mechanism 

 must be a part of a larger framework? 



B. B. Parrish: Any attempt at defmition involves building upon prior 

 terms. 'Population' is a case in point. In fisheries research the dynamic unit 

 is the 'stock', which is treated as a unit for management purposes not 

 necessarily equivalent to the total 'population'. Some 'populations' include 

 several species, and in such instances 'self-regulation' could involve inter- 

 specific competition. 



L. B. Slobodkin: Skellam seems to be seeking for words with 'no 

 theoretical content'. I feel that in this he is looking towards mathematical 

 expressions. But the mathematician is clearer about what he is trying to do. 

 In our case, we can easily define a word and then spend years looking for 

 a case which fits our rigorous conditions. If, however, we first observe a 

 phenomenon and then derive a word to describe it, our terms almost inevit- 

 ably have a 'theoretical content'. 



Solomon has said that regulation imphes feed-back. In that case, can we 

 not say that 'A population shows self-regulation when some property of the 

 population participates in the feed-back system' ? 



D. H. Chitty: I think that is too broad a definition. In that case surely 

 any property of the population which leads to feed-back would be self- 

 regulatory ? 



L. B. Slobodkin: I do not think so. 



G. C. Varley: I think this discussion has made it plain that we a.re not 

 clear about the terms we use. Surely we should set up a mechanism to 

 obtain a clarification? Something should be attempted, to obtain concise 

 and useful definitions. 



