4«2
_
EFFECT OF TRAWLING ON CRABS.
,_
-
_
lobsters, and 2018 crabs,—from that in 1883—1887.
The
,
decrease, however, seems to be in no way connected with, the
'
trawling industry. An increase both in quantity and value
—has since occurred.
Trawling close inshore with a small— —
_
',
-
meshed net (naturalists’) often produces large numbers of
_
swimming crabs, but such is a rare occurrence on board an
ordinary trawler.
.
’
'
While, therefore, in trawling the injury to the crustaceans
inhabiting the bottom is considerable‘, it has to be borne
_
mind that the pelagic crustacean fauna is one of the most
.
'
marked features in the ocean, from the north to the south pole, '
and some
of its members, e.g., baruacles attached to oating
_
timber, sessile—eyed crustaceans, schizopods,
thysanop0ds
-"_
are
large en0ugh to be the food of haddocks and herrings.
'
’ _
Moreover, vast swarms of the smaller copépod's noush the '.
younger food-shes, and other types, again, are eaten by the —
'
larger shes.
Near the mouth of the Forth, at certain seasons
'
.
(viz., in autumn), the water near the ‘Hairst’ at Crail is almost
.
'thickened by Thysanoessa.
The tow-nets, under these cir-…g
-
cumstances, soon_become lled with their masses.
Some, how—'
,
'
,
ever, may be disposed to treat the ,pelagic crustacean food, in '-- '
,
connection with the nourishment of the shes, with indifference,
,
'
deeming such-small animals of little moment in contrast with
'
the more substaritial denizens of the bottom.
Irrespective of
',
,
the cirCumsta'nce that where they abound other and larger
'
"
forms are in- their wake, the fact that so, gigantic an animal as'
'
j _
'
the right, or whalebone—whale of commerce, lives solely upon
'
—
such pelagic food in the Arctic seas, is sufcient to shOw how
'
_
important au element this oating 'or swimming fauna is in
' _
:
'
regard to the
of the sheries.
The larger part of the
'
,
masSes- in the ”cow—net, kindly used in 1893 by Dr Allan of
_
:
,
Glasgow on board the whaling—ship ,‘Aurora’ of Dundee, con—'
Sisted of the little crustace‘anS
'
(copepods) above—mentioned,
‘
and this in the actual food—line of the whale as it swam to and
,
fro -in the water near: au ice—pack. -In‘ our own waters, in
addition to what“ is mentioned above, the sea—acorns, which so
Ï
Î '_ extensively cover rocks,
shells, and other structures
—_
Within tide—mark, as well in deeper water (not to speak of-
_
EFFECT OF TRAWLING ON CRABS.
,_
-
_
lobsters, and 2018 crabs,—from that in 1883—1887.
The
,
decrease, however, seems to be in no way connected with, the
'
trawling industry. An increase both in quantity and value
—has since occurred.
Trawling close inshore with a small— —
_
',
-
meshed net (naturalists’) often produces large numbers of
_
swimming crabs, but such is a rare occurrence on board an
ordinary trawler.
.
’
'
While, therefore, in trawling the injury to the crustaceans
inhabiting the bottom is considerable‘, it has to be borne
_
mind that the pelagic crustacean fauna is one of the most
.
'
marked features in the ocean, from the north to the south pole, '
and some
of its members, e.g., baruacles attached to oating
_
timber, sessile—eyed crustaceans, schizopods,
thysanop0ds
-"_
are
large en0ugh to be the food of haddocks and herrings.
'
’ _
Moreover, vast swarms of the smaller copépod's noush the '.
younger food-shes, and other types, again, are eaten by the —
'
larger shes.
Near the mouth of the Forth, at certain seasons
'
.
(viz., in autumn), the water near the ‘Hairst’ at Crail is almost
.
'thickened by Thysanoessa.
The tow-nets, under these cir-…g
-
cumstances, soon_become lled with their masses.
Some, how—'
,
'
,
ever, may be disposed to treat the ,pelagic crustacean food, in '-- '
,
connection with the nourishment of the shes, with indifference,
,
'
deeming such-small animals of little moment in contrast with
'
the more substaritial denizens of the bottom.
Irrespective of
',
,
the cirCumsta'nce that where they abound other and larger
'
"
forms are in- their wake, the fact that so, gigantic an animal as'
'
j _
'
the right, or whalebone—whale of commerce, lives solely upon
'
—
such pelagic food in the Arctic seas, is sufcient to shOw how
'
_
important au element this oating 'or swimming fauna is in
' _
:
'
regard to the
of the sheries.
The larger part of the
'
,
masSes- in the ”cow—net, kindly used in 1893 by Dr Allan of
_
:
,
Glasgow on board the whaling—ship ,‘Aurora’ of Dundee, con—'
Sisted of the little crustace‘anS
'
(copepods) above—mentioned,
‘
and this in the actual food—line of the whale as it swam to and
,
fro -in the water near: au ice—pack. -In‘ our own waters, in
addition to what“ is mentioned above, the sea—acorns, which so
Ï
Î '_ extensively cover rocks,
shells, and other structures
—_
Within tide—mark, as well in deeper water (not to speak of-