The data
from numerous sources demonstrate that on stable fisheries there is a weight-to-weight
relationship between predatory fish and prey which are available to them. Pike
biomasses of 10-13% of that of their available prey have been cited. Using the
ratio of 1:10, one can predict that 300lb of prey fish would be able to support
some 30lb of pike without any long term adverse effects on the abundance of either
type of fish.
This balance is a so-called
dynamic equilibrium. It will swing one way or another in response to entirely
natural phenomena (such as spawning success or outbreaks of disease). Equally,
if the balance swings markedly in favour of one 'side' ecological pressures ensure
that, eventually, it will swing back in the other direction.
If
this were not the case there would be countless examples of fisheries in which
pike have become dominant or have totally eradicated the stocks of prey fish,
and this would be a continuing situation on unmanaged waters. There is only one
known example of pike eating themselves 'out of house and home' and eradicating
their prey.