MANAGEMENT OF FISHERY RESOURCES
47
in a single national fishery if the nationals concerned used, as do the
Portuguese. both types of gear.
There have also been various practical and administrative difficulties in putting mesh regulation into force-questions of how
precisely to measure meshes, the use of extra pieces of netting t o reduce
chafing which may also obstruct the meshes, and, particularly, the
question of enforcement. These problems should not be underestimated,
but good progress is being made towards solving them. So far as it is
possible for them to go, regulations of the sizes caught have been
reasonably successfully introduced and the major problem facing all
commissions is the control on the total amount of fishing.
Most of the commissioiis referred to in the previous section have a t
least discussed the problem of restricting the amount of fishing, and
several have some effective restriction, generally in terms of a limit to
the total catch. The success of effort regulations may be gauged by
whether they have achieved both the biological objective (to build up
the stock, maintain it at the desired level and hence take the optimum
catch), and the economic objective (to reduce costs in proportion to the
reduction in fishing mortality, and hence achieve the potential surplus
of value over costs).
An outstanding example of management t h a t is successful on both
counts is that of the fur seal (Callorhinzcs uysinus L.) in the North
Pacific. The stocks have built up very greatly (Kenyon et al., 1956;
Chapman, 1961), so much so that, since to some extent the fur seals eat
fish of commercial valuc, it has been argued that they have increased
to an undesirable degree when considering the best use of the marine
resources of the North Pacific as a whole. Most of the harvest is taken
as surplus juvenile males when they are segregated in compact groups
on the breeding islands, so that the cost of operations are presumably
low. The figures of resultant net economic yield are not available, but
150/, of the q o s s value of several million dollars of the catch from the
Pribilofs is sent to Japan and Canada, in consideration for not carrying out seeling on the high seas, and it is doubtful whether the net
profit to the U.S. Government (who carries out the operations) is any
less.
As mentioned in an earlier section, in biological terms the restriction
on the catches of halibut off the uest coast of North America has been
successful in building up the stocks of halibut after they had been
severely depleted ; between 1031 (when regulations first came into
force) and 1960 the stocks in different areas increased two t o three
times, and the catches rose by up to 50% (Thompson, 1950; I.N.P.F.C.,
1 9 6 2 ~ ; Chapman et al., 1962). However, because of the scramble
47
in a single national fishery if the nationals concerned used, as do the
Portuguese. both types of gear.
There have also been various practical and administrative difficulties in putting mesh regulation into force-questions of how
precisely to measure meshes, the use of extra pieces of netting t o reduce
chafing which may also obstruct the meshes, and, particularly, the
question of enforcement. These problems should not be underestimated,
but good progress is being made towards solving them. So far as it is
possible for them to go, regulations of the sizes caught have been
reasonably successfully introduced and the major problem facing all
commissions is the control on the total amount of fishing.
Most of the commissioiis referred to in the previous section have a t
least discussed the problem of restricting the amount of fishing, and
several have some effective restriction, generally in terms of a limit to
the total catch. The success of effort regulations may be gauged by
whether they have achieved both the biological objective (to build up
the stock, maintain it at the desired level and hence take the optimum
catch), and the economic objective (to reduce costs in proportion to the
reduction in fishing mortality, and hence achieve the potential surplus
of value over costs).
An outstanding example of management t h a t is successful on both
counts is that of the fur seal (Callorhinzcs uysinus L.) in the North
Pacific. The stocks have built up very greatly (Kenyon et al., 1956;
Chapman, 1961), so much so that, since to some extent the fur seals eat
fish of commercial valuc, it has been argued that they have increased
to an undesirable degree when considering the best use of the marine
resources of the North Pacific as a whole. Most of the harvest is taken
as surplus juvenile males when they are segregated in compact groups
on the breeding islands, so that the cost of operations are presumably
low. The figures of resultant net economic yield are not available, but
150/, of the q o s s value of several million dollars of the catch from the
Pribilofs is sent to Japan and Canada, in consideration for not carrying out seeling on the high seas, and it is doubtful whether the net
profit to the U.S. Government (who carries out the operations) is any
less.
As mentioned in an earlier section, in biological terms the restriction
on the catches of halibut off the uest coast of North America has been
successful in building up the stocks of halibut after they had been
severely depleted ; between 1031 (when regulations first came into
force) and 1960 the stocks in different areas increased two t o three
times, and the catches rose by up to 50% (Thompson, 1950; I.N.P.F.C.,
1 9 6 2 ~ ; Chapman et al., 1962). However, because of the scramble