6
J. A. GULLAND AND J. E. CARROZ
may also conflict with fisheries. However, these problems will not be
considered further here; nor will this article be concerned with the
problems of fish culture in ponds, brackish water or enclosed parts of
the sea, except that such culture may have an indirect effect on the
open water fisheries by increasing the demand for cheap supplies of
food for the choicer varieties of fish being farmed.
The problems of overfishing arise because, in default of definite
arrangements, the fishery resources are not the responsibility of any
single person or body. Next year’s catches depend on how much is
taken this year, but in the open sea the individual fisherman can do
little to ensure better fishing for himself next year-if lie does not catch
fish while he can, someone else will catch them. Thus effective management depends on the participation of all, or at least of the great
majority, of those exploiting a given stock of fish. The problems are
more complex when many countries are concerned or when more than
one species of fish is caught (especially when there may be biological
interactions between the stocks, e.g. one species being the main food
of another), but the main problems are essentially the same even when
a single stock is exploited by a single country.
The first problem is biological: t o understand the population
dynamics of the stock or stocks concerned, and thus make quantitative
assessments of the probable effect on the stocks and on future catches
of any regulatory measure. Until this biological understanding is
available, it is unrealistic to consider the other problems of regulation,
though at first the biological study need not be very intense. A simple
study may show that a stock is in urgent need of regulation, and any
effective measure would be bound to improve matters; only as the
first measures take effect will more detailed biological data be needed
to determine the precise needs for further measures. Too often conservation measures have been delayed, and great damage done to the
stock and the fishery on it by the demand for complete and conclusive
biological evidence; the final conclusive proof that a stock is being
depleted is when it becomes extinct.
Biological considerations are, of course, only the first step; the aim
of fishery management is not primarily to maintain the stocks of fish,
but to make the best use of the resources in terms of larger or cheaper
supplies of fish to the consumer, better income to the fishermen, etc.
The desired result of regulation, especially when the objective is t o take
about the same catch more cheaply, can therefore only be ensured by
taking into account the probable economic and other non-biological
effects of proposed regulation. Economic and similar considerations
will also become increasingly important in resolving disputes between
J. A. GULLAND AND J. E. CARROZ
may also conflict with fisheries. However, these problems will not be
considered further here; nor will this article be concerned with the
problems of fish culture in ponds, brackish water or enclosed parts of
the sea, except that such culture may have an indirect effect on the
open water fisheries by increasing the demand for cheap supplies of
food for the choicer varieties of fish being farmed.
The problems of overfishing arise because, in default of definite
arrangements, the fishery resources are not the responsibility of any
single person or body. Next year’s catches depend on how much is
taken this year, but in the open sea the individual fisherman can do
little to ensure better fishing for himself next year-if lie does not catch
fish while he can, someone else will catch them. Thus effective management depends on the participation of all, or at least of the great
majority, of those exploiting a given stock of fish. The problems are
more complex when many countries are concerned or when more than
one species of fish is caught (especially when there may be biological
interactions between the stocks, e.g. one species being the main food
of another), but the main problems are essentially the same even when
a single stock is exploited by a single country.
The first problem is biological: t o understand the population
dynamics of the stock or stocks concerned, and thus make quantitative
assessments of the probable effect on the stocks and on future catches
of any regulatory measure. Until this biological understanding is
available, it is unrealistic to consider the other problems of regulation,
though at first the biological study need not be very intense. A simple
study may show that a stock is in urgent need of regulation, and any
effective measure would be bound to improve matters; only as the
first measures take effect will more detailed biological data be needed
to determine the precise needs for further measures. Too often conservation measures have been delayed, and great damage done to the
stock and the fishery on it by the demand for complete and conclusive
biological evidence; the final conclusive proof that a stock is being
depleted is when it becomes extinct.
Biological considerations are, of course, only the first step; the aim
of fishery management is not primarily to maintain the stocks of fish,
but to make the best use of the resources in terms of larger or cheaper
supplies of fish to the consumer, better income to the fishermen, etc.
The desired result of regulation, especially when the objective is t o take
about the same catch more cheaply, can therefore only be ensured by
taking into account the probable economic and other non-biological
effects of proposed regulation. Economic and similar considerations
will also become increasingly important in resolving disputes between