46
J. A. GULLAND AND J. E. CARROZ
the International Whaling Commission has set size limits which should
protect the small, generally immature, whales, and also, for pelagic
operations, almost all the female sperm whales (for this species, which
is polygamous, rational management is presumably to limit the kill
mainly or entirely to the surplus males). Unfortunately, there is good
evidence that these size limits have, at least in some years, been
extensively violated; this underlines the need for some system of
international inspection or enforcement, especially when the incentive
for infringement is large. As the experience of the Antarctic baleen
whaling shows (in which infringements of the size limits have probably
not been serious), size limits by themselves are very far from being a
sufficient method of management.
Both North Atlantic Commissions have been deeply involved with
control of the sizes of fish caught, especially regulation of the size of
meshes in trawl nets, and such regnlations are in force, or in the process
of being brought into force, in most of the areas with which they are
concerned (see Annual Reports of I.C.N.A.F. and N.E.A.F.C.). I n fact
in many areas the limit t o which mesh regulations can be usefully
applied, a t least under the framework of the present commissions, is
being approached. I n part this is because the present mesh size is the
optimum a t the present rate of fishing (this may be so, for example, for
the sole in the North Sea), but more often because a further increase
in mesh size would be unacceptable for other reasons. Earlier it was
shown that the presence of relatively small-sized species of fish (e.g.
soles in the North Sea), of which the catch would be reduced if larger
meshes were used, prevents the use of mesh sizes which would be much
better for the larger species (e.g. cod and plaice). This is one example
of the inequitable results of mesh (or in fact any other) regulation
likely to occur in a heterogeneous fishery. Another example in a single
species fishery is that for cod off the west coast of Greenland, which is
fished by both otter trawlers and vessels using hooks and lines; the
immediate losses of small fish when the larger mesh is used are confined
to the trawlers, but the long-term benefits from increased stocks accrue
to both groups of fishermen (I.C.N.A.F., 1966). The net long-term
benefits to the liners will therefore always be greater than those of the
trawlers. Moderate increases in mesh size (up t o and somewhat above
those so far proposed) would benefit both gears, but still larger meshes
(up to 170 mm) would increase the total catch, but only at the cost of
reducing the catch of trawlers. Since the Comlr\ission’s statutes contain
no provision whereby some of the benefits which the liners would gain
can be transferred from them to the trawlers, such mesh sizes are clearly
unacceptable to the trawler fishermen. They would still be unacceptable
J. A. GULLAND AND J. E. CARROZ
the International Whaling Commission has set size limits which should
protect the small, generally immature, whales, and also, for pelagic
operations, almost all the female sperm whales (for this species, which
is polygamous, rational management is presumably to limit the kill
mainly or entirely to the surplus males). Unfortunately, there is good
evidence that these size limits have, at least in some years, been
extensively violated; this underlines the need for some system of
international inspection or enforcement, especially when the incentive
for infringement is large. As the experience of the Antarctic baleen
whaling shows (in which infringements of the size limits have probably
not been serious), size limits by themselves are very far from being a
sufficient method of management.
Both North Atlantic Commissions have been deeply involved with
control of the sizes of fish caught, especially regulation of the size of
meshes in trawl nets, and such regnlations are in force, or in the process
of being brought into force, in most of the areas with which they are
concerned (see Annual Reports of I.C.N.A.F. and N.E.A.F.C.). I n fact
in many areas the limit t o which mesh regulations can be usefully
applied, a t least under the framework of the present commissions, is
being approached. I n part this is because the present mesh size is the
optimum a t the present rate of fishing (this may be so, for example, for
the sole in the North Sea), but more often because a further increase
in mesh size would be unacceptable for other reasons. Earlier it was
shown that the presence of relatively small-sized species of fish (e.g.
soles in the North Sea), of which the catch would be reduced if larger
meshes were used, prevents the use of mesh sizes which would be much
better for the larger species (e.g. cod and plaice). This is one example
of the inequitable results of mesh (or in fact any other) regulation
likely to occur in a heterogeneous fishery. Another example in a single
species fishery is that for cod off the west coast of Greenland, which is
fished by both otter trawlers and vessels using hooks and lines; the
immediate losses of small fish when the larger mesh is used are confined
to the trawlers, but the long-term benefits from increased stocks accrue
to both groups of fishermen (I.C.N.A.F., 1966). The net long-term
benefits to the liners will therefore always be greater than those of the
trawlers. Moderate increases in mesh size (up t o and somewhat above
those so far proposed) would benefit both gears, but still larger meshes
(up to 170 mm) would increase the total catch, but only at the cost of
reducing the catch of trawlers. Since the Comlr\ission’s statutes contain
no provision whereby some of the benefits which the liners would gain
can be transferred from them to the trawlers, such mesh sizes are clearly
unacceptable to the trawler fishermen. They would still be unacceptable