THE SEA FISHERIES
275
through air or water it will move in a direction outwards.
The well—known method of poaçhing for troùt by means of
an
“
otter ” is based on this principle.
A at piece of
wood set at an angle is drawn through the water by the
poacher on the bank.
As he goes forward the “ otter ” also
.
goes forward, but owing to the angle at which it is set “it
moves ever further out from the bank, towing behind it a
string of lures which are thus presented to sh lying far
beyond the reach of anyone upon the bank shing in a
sportsmanlike ”manner.
-
,
In the case of the otter-trawl two “
otters ”
or “ doors ”
are
used.
To these the sides of the net’s mouth are
attached, and they are set at such angles that as they are
drawn
over
the
bottom they diverge farther and
farther from the centre of the net’s mouth until an ‘equi‘_
librium point is reached and the mouth of the net isstretched
agape (Plate 100). The upper edge of the mouth of the net
is in this case not straight, but like the foot-rope it curves
backwards, but the—foot-rope is the longer of the two so
that the net immediately behind the head—line forms a
roof over it.
The tremendous strain upon‘the bag of the
net as it moves through the water keeps the mouth of the
net open verticallÿ. The otter
“
doors -” are made of
heavy iron—bound wood and are eight t0.nine feet in length,
'
and four to ve feet high.
The lower edge that runs along
‘
the sea bottom is heavin encased with iron to
form a Shoe
three inches thick.
-
"
"'
'
,
In the case of the beam—trawl we saw that the opening
'
of the net was limited by the size of the, frame.
Above a
.
-
certain size the frame becomestoo large and cumbersome
_
for practice.
With the
.on
the other hand,,
the opening that a net may
have is limited only by the
actual
opening of the net itself, the " doors
being
.
,
practically the same size forany net, their Weight 1alô‘e
'