278
—
_
THE SEAS
catchmg these in the trawl.also.
When shing for herring
'
however the mesh of the net is semewhat reduced and the
trawl is towed at nearly the full speed of the vessel, as
opposed to the two and a half to four knots under usual
trawling conditions.
'
'
,
DRIFT FISHING
Most of our food sh live on or near the bottom and can
be scooped up by the trawl, but two or three species, such
as the herring and the mackerel, live a great part of their
lives swimming in huge shoals in the water layers above the
bottom.
In
the
daytime they are usually
rather deep in the water, but at dusk and during the night
they come up very close tô the surface itself. It is ”then
that they can be most easily caught in the specially
'
designed nets known as “ drift nets.” This habit of coming
towards the” surface at night is not peculiar to herring and
màckérel.
Those drifting‘animals that form the plankton
.
show these habits and such vertical migrations are also
common to many other “sh.
The hake' is an excellent
example ; so regularly does this sh leave the bottom at
the shermen never traw1 for them except in
the-daÿtime, when they are on the bottom.
_
f
The drift nets by Which theherrings are caught act on
& principle very different from that of
There is
no bag into which the sh are sWept.
A drift net is literally
a. wallo‘f netting 'hanging vertiCally _in the-Water, and in
_
this case ”it is the mesh of the net that catChes the sh
(Plate 98). This mesh is made. So that the herring can
'
eXactly push his head through, but not his body.
When
once the head has been pushed-in beyond the gill—covers
.
it is‘im'possible-to get‘it—out again, because, the gill-covers
being slightly raised, the twine of which the mesh is made
slipsün‘der them. The her-rings,— swimming in vast shoals,
—
_
THE SEAS
catchmg these in the trawl.also.
When shing for herring
'
however the mesh of the net is semewhat reduced and the
trawl is towed at nearly the full speed of the vessel, as
opposed to the two and a half to four knots under usual
trawling conditions.
'
'
,
DRIFT FISHING
Most of our food sh live on or near the bottom and can
be scooped up by the trawl, but two or three species, such
as the herring and the mackerel, live a great part of their
lives swimming in huge shoals in the water layers above the
bottom.
In
the
daytime they are usually
rather deep in the water, but at dusk and during the night
they come up very close tô the surface itself. It is ”then
that they can be most easily caught in the specially
'
designed nets known as “ drift nets.” This habit of coming
towards the” surface at night is not peculiar to herring and
màckérel.
Those drifting‘animals that form the plankton
.
show these habits and such vertical migrations are also
common to many other “sh.
The hake' is an excellent
example ; so regularly does this sh leave the bottom at
the shermen never traw1 for them except in
the-daÿtime, when they are on the bottom.
_
f
The drift nets by Which theherrings are caught act on
& principle very different from that of
There is
no bag into which the sh are sWept.
A drift net is literally
a. wallo‘f netting 'hanging vertiCally _in the-Water, and in
_
this case ”it is the mesh of the net that catChes the sh
(Plate 98). This mesh is made. So that the herring can
'
eXactly push his head through, but not his body.
When
once the head has been pushed-in beyond the gill—covers
.
it is‘im'possible-to get‘it—out again, because, the gill-covers
being slightly raised, the twine of which the mesh is made
slipsün‘der them. The her-rings,— swimming in vast shoals,