The sensitivity of exploited populations to environmental “noise”, and the implications for management

Abstract

The sensitivity of natural populations to environmental noise is largely determined by their response to transient perturbations. The most important features of the transient response are described by the return time, which is the characteristic time taken for the population to return to equilibrium after perturbation. It is shown that

1) the return time may either increase or decrease when a population is exploited, depending onthe nature of the mechanisms which regulate population size;

2) the sensitivity of population size to noise may either increase or decrease as return time in-creases, depending on the way in which the “noise” acts to perturb the population.

It is thus not possible to make any firm statement about the effect of exploitation on sensitivity to noise without understanding in some detail the regulatory mechanisms and sources of fluctuations for the population in question. Nevertheless the possibility that sensitivity to noise may be increased by exploitation exists, and should be borne in mind when formulating management strategies.