  The safeguarding of resources is one of the principal subjects of halieutics
studies. Among the solutions proposed to avert the disappearance of species,
the setting in place of no take reserves is often mentioned. Most work on this
subject, theoretical as well as applied, was undertaken in recent years. In
this paper, we seek to compare two different models presented in existing
literature by highlighting their underlying assumptions. Both models were
derived from what is often referred to as the "model of Schaefer-Clark"
(reference to the work of the last author on Mathematical Bioeconomics : Clark
[7]). We show that various variations of this model lead to properties that can
be very different.
