328
THE SEAS
may be taken to mean that a quarter of the catchable
plaiceare taken out each year—that is those sh which are .
,
large enough to be retained by the meshes of the net.
At
rst sight one does not think this to be really possible.
We say, the sea is so vast that the eorts of man can have
_
no effect upon the sh population.
But“ when _we
realize
that a sh like the plaice inhabits only the comparatively
water, and that this water is of a very limited
extent compared with the deep oceans, and when we are
told that the area covered by the nets of all British steam
'
trawlers in the year 1926 was about.108,ooo square
miles
and the area of the North Sea itself being only about I 30,000
square miles, we realize that the chances in favour of the
plaiCe are small indeed.
Especially is'this so since the
trawling area is not distributed all over the North Sea,
but is concentrated on certain grounds where the plaice ,
are most abundant.
"
Let us now turn for a while from the problems of the
'
plaice and follow the study of the life-history of that
pelagic sh,
herring.
in
chapter we have
described the general methods of locating. the Spawning
grounds of the herring, by noting the presence of ripe sh,
by searching for eggs on the bottom with the grab, and by
seeking for “spawny
”
haddock..
…
_
A study of the distribution of these spawning grounds
'
shows that the herrîng choose out regions in the close vicinity
of the coast and especially of the estuaries of rivers.
It is next necessary to follow the movement of the_young
herring as soon as they have hatch‘ed-Ïrom their demersal
The baby sh very soon after hatching make their
way up from'the'bottom into the water layers nearer the
Surface-, and here
maybe Caughtby means of tow—nets
in the same way as the young plaice. '
But When the herr1ng is about three or four,moths old
THE SEAS
may be taken to mean that a quarter of the catchable
plaiceare taken out each year—that is those sh which are .
,
large enough to be retained by the meshes of the net.
At
rst sight one does not think this to be really possible.
We say, the sea is so vast that the eorts of man can have
_
no effect upon the sh population.
But“ when _we
realize
that a sh like the plaice inhabits only the comparatively
water, and that this water is of a very limited
extent compared with the deep oceans, and when we are
told that the area covered by the nets of all British steam
'
trawlers in the year 1926 was about.108,ooo square
miles
and the area of the North Sea itself being only about I 30,000
square miles, we realize that the chances in favour of the
plaiCe are small indeed.
Especially is'this so since the
trawling area is not distributed all over the North Sea,
but is concentrated on certain grounds where the plaice ,
are most abundant.
"
Let us now turn for a while from the problems of the
'
plaice and follow the study of the life-history of that
pelagic sh,
herring.
in
chapter we have
described the general methods of locating. the Spawning
grounds of the herring, by noting the presence of ripe sh,
by searching for eggs on the bottom with the grab, and by
seeking for “spawny
”
haddock..
…
_
A study of the distribution of these spawning grounds
'
shows that the herrîng choose out regions in the close vicinity
of the coast and especially of the estuaries of rivers.
It is next necessary to follow the movement of the_young
herring as soon as they have hatch‘ed-Ïrom their demersal
The baby sh very soon after hatching make their
way up from'the'bottom into the water layers nearer the
Surface-, and here
maybe Caughtby means of tow—nets
in the same way as the young plaice. '
But When the herr1ng is about three or four,moths old