336
,
THE SEAS
the rst year after the war, ”showing that the.sh are being
’
removed at such a rat—e that they are never allowed to reach
.
a good size.
These results may be taken as direct evidence
that shing is being carried on to a dangerously heavy
degree.
The benecial effects of shing up to a certain
extent, however,, Were shown by the fact that after the
rst year, when large numbers of the old plaice were
removed, the growth rate temporarily improved.
The rst care then of shery research is what is known as
a rational exploitation of the sea.
That is, that the areas
concerned shall be shed right up to their limit, without
it and harming the stock for future years or
‘
upsetting too severely the balance of nature.
To discover
these limits the productivity of the sea must be estimated ;
the lite—histories of all the shes, and animals and plants that
concern them, must be worked out; the causes of the
'
various uctuations that occur from year to year
in the
supply of different sh must be-f_ound and these uctua—
tions must be discriminated-‘Om those that may have been
brought about by overshing.
,
-
Although many of the methods employed _—in sherÿ
research have been mentioned in the above outline of
the study of two such sh as the plaice and the herrig,
there are still others that remain unmenti0ned.
Space
"
‘
will not allow of further expansion on this subject but
enough should have been said to impress the reader with
the immense amount of labour that is involved in
investigations. _We cannot be satised with one or two
observations only.
Day in, clay
information must be
gathered from all possible” sources ; statisticsof sh landinga
“measurements ofsh, samples of the bottom, collections°
-
of plankton, observations of currents, temperatures
and
saltness, all are needed.
Furthermore we cannot be content
with such information gathered over a period of
one
,
THE SEAS
the rst year after the war, ”showing that the.sh are being
’
removed at such a rat—e that they are never allowed to reach
.
a good size.
These results may be taken as direct evidence
that shing is being carried on to a dangerously heavy
degree.
The benecial effects of shing up to a certain
extent, however,, Were shown by the fact that after the
rst year, when large numbers of the old plaice were
removed, the growth rate temporarily improved.
The rst care then of shery research is what is known as
a rational exploitation of the sea.
That is, that the areas
concerned shall be shed right up to their limit, without
it and harming the stock for future years or
‘
upsetting too severely the balance of nature.
To discover
these limits the productivity of the sea must be estimated ;
the lite—histories of all the shes, and animals and plants that
concern them, must be worked out; the causes of the
'
various uctuations that occur from year to year
in the
supply of different sh must be-f_ound and these uctua—
tions must be discriminated-‘Om those that may have been
brought about by overshing.
,
-
Although many of the methods employed _—in sherÿ
research have been mentioned in the above outline of
the study of two such sh as the plaice and the herrig,
there are still others that remain unmenti0ned.
Space
"
‘
will not allow of further expansion on this subject but
enough should have been said to impress the reader with
the immense amount of labour that is involved in
investigations. _We cannot be satised with one or two
observations only.
Day in, clay
information must be
gathered from all possible” sources ; statisticsof sh landinga
“measurements ofsh, samples of the bottom, collections°
-
of plankton, observations of currents, temperatures
and
saltness, all are needed.
Furthermore we cannot be content
with such information gathered over a period of
one