10
J. A. GULLAND AND J. E. CARROZ
especially being a major interest to Scottish fishermen, and Scottish
fishing has not expanded to distant waters to anything like the same
extent as English fishing. Thus it is not clear whether the fishing on
these species has declined to the same extent as the fishing on plaice
though the cod stocks in the central North Sea seem to have also
benefited from reduced fishing (M.A.F.F., U.K., 1962). Certainly the
recent good catches have been due in part to outstanding year-classes,
especially the 1962 haddock year-class (M.A.F.F., U.K., 1966). There
may well have been a decrease in effort; also haddock catches in
particular are likely to have benefited from the larger mesh sizes
introduced under the 1946 Overfishing Convention (I.C.E.S., 1957).
The diversion of the main attention of some of the countries bordering
the North Sea has therefore allowed some a t least of the North Sea
demersal stocks to recover temporarily to a level not far from the
optimum. However, a t this level of fishing any increase in fishing
would, in the long term, reduce the total catch. The recent success of
North Sea fishing is attracting some of the resources of ships and capital
back to the North Sea, and without some restriction only a fraction of
the resources at present devoted to distant water fishing could quickly
reduce the North Sea stocks again to the low level of the 1930s.
Temporarily, though, some North Sea demersal stocks have
benefited from diversion of fishing to other stocks, but these latter
stocks have in their turn become depleted. The first of the distant
water stocks to become depleted were the small but economically
attractive stocks, such as the plaice off Iceland and in the Barents Sea;
the abundance of these stocks, as measured by the catch per hour, had
been reduced as early as 1925 to a small fraction of their initial level.
Russell (1942) and more recently Gulland (1961) describe clearly the
decline in catch per hour of plaice and other species by English trawlers
fishing a t Iceland, and the relation of this decline to the changes in the
total amount of fishing. The larger cod stocks were able to support a
greater total amount of fishing, but by the mid-1950s they too werc
being heavily exploited. For instance, despite an increase in the amoufit
of fishing since 1946 of several times (possibly as much as tenfold), the
catches of cod from the Arcto-Norwegian stock (living in the waters
between north Norway, Russia and Spitsbergen) has fluctuated between
600 000 and I 300 000 tons with no evidence of any increasing trend
(see Fig. 3) (I.C.E.S., 1966).
I n the last decade the further expansion of European fishing,
including diversion of some of the effort formerly engaged in fishing the
depleted stocks of the north-east Atlantic, and also increasing numbers
of new freezer and factory trawlers (Fig. 4), especially from eastern
J. A. GULLAND AND J. E. CARROZ
especially being a major interest to Scottish fishermen, and Scottish
fishing has not expanded to distant waters to anything like the same
extent as English fishing. Thus it is not clear whether the fishing on
these species has declined to the same extent as the fishing on plaice
though the cod stocks in the central North Sea seem to have also
benefited from reduced fishing (M.A.F.F., U.K., 1962). Certainly the
recent good catches have been due in part to outstanding year-classes,
especially the 1962 haddock year-class (M.A.F.F., U.K., 1966). There
may well have been a decrease in effort; also haddock catches in
particular are likely to have benefited from the larger mesh sizes
introduced under the 1946 Overfishing Convention (I.C.E.S., 1957).
The diversion of the main attention of some of the countries bordering
the North Sea has therefore allowed some a t least of the North Sea
demersal stocks to recover temporarily to a level not far from the
optimum. However, a t this level of fishing any increase in fishing
would, in the long term, reduce the total catch. The recent success of
North Sea fishing is attracting some of the resources of ships and capital
back to the North Sea, and without some restriction only a fraction of
the resources at present devoted to distant water fishing could quickly
reduce the North Sea stocks again to the low level of the 1930s.
Temporarily, though, some North Sea demersal stocks have
benefited from diversion of fishing to other stocks, but these latter
stocks have in their turn become depleted. The first of the distant
water stocks to become depleted were the small but economically
attractive stocks, such as the plaice off Iceland and in the Barents Sea;
the abundance of these stocks, as measured by the catch per hour, had
been reduced as early as 1925 to a small fraction of their initial level.
Russell (1942) and more recently Gulland (1961) describe clearly the
decline in catch per hour of plaice and other species by English trawlers
fishing a t Iceland, and the relation of this decline to the changes in the
total amount of fishing. The larger cod stocks were able to support a
greater total amount of fishing, but by the mid-1950s they too werc
being heavily exploited. For instance, despite an increase in the amoufit
of fishing since 1946 of several times (possibly as much as tenfold), the
catches of cod from the Arcto-Norwegian stock (living in the waters
between north Norway, Russia and Spitsbergen) has fluctuated between
600 000 and I 300 000 tons with no evidence of any increasing trend
(see Fig. 3) (I.C.E.S., 1966).
I n the last decade the further expansion of European fishing,
including diversion of some of the effort formerly engaged in fishing the
depleted stocks of the north-east Atlantic, and also increasing numbers
of new freezer and factory trawlers (Fig. 4), especially from eastern