In addition to the provision of size limits it is strongly recommended
that certain portions of the rivers be closed for rest periods covering
several years. It might be thought that in regions of extreme depletion
the operation of a size limit would, by making the fishery less
profitable, have the effect of causing a practical rest period, but
this can not be expected, for, stimulated by the high price of shells
and the ever-present hope of making a pearl find, the local shellers
will hardly ever desist entirely from the fishery.
No better way of giving protection to mussels can be found than that of
entirely stopping the shelling upon a series of beds, although the plan
must be applied in such a way as not to reduce the supply of mussels
unduly and suddenly and with as careful regard as possible to the
established interest of communities.