TRAWL FISHERIES
Unlike the drift net, which only catches fish of one species and of
fairly uniform size when they are swimming near the surface, the trawl
net scoops up practically all the inhabitants of the sea bottom,
including round fish, e.g. cod and haddock; flat fish, e.g. sole and
plaice, as well as various invertebrates (jelly fish), and marine
plants and stones. The trawl is essentially a flattened, conical net
that is dragged open-mouthed along the sea bottom. The two kinds of
trawl in common use—the beam trawl and the otter trawl—differ in the
method that is adopted for keeping open the mouth of the net. The beam
trawl is used by sailing vessels, the otter trawl by steamers.
Sailing trawlers are divided into two classes: first class smacks
and second class cutters. The smack is a two masted vessel with fore
and aft rig, generally making a five or six day voyage, and trawling
in depths of up to 40 fathoms. The cutter makes shorter voyages—20
hours—and generally keeps within territorial waters.
To work a beam trawl successfully, it is necessary to know the
character of the sea bottom, whether rough or smooth, and also the time
and direction of the tide. The net is trawled with the tide a little
faster than it is running, so that sufficient resistance is encountered
to keep the net extended. In shooting the trawl, great care must be
taken to make it alight on its runners in the correct position for
trawling. If the net be twisted, or if it alight upside down, it has
been shot “foul,” and has to be hauled up and shot again. In preparing
for a shot the net is lowered over the side by adjusting the bridle
ropes, and the beam is coaxed into its proper position while the net
is still near the surface. The net is then gradually lowered, the boat
moving slowly forward. The trawl is generally hauled for the duration
of a tide—that is, six hours—during which time it will travel about
15 miles. The net is generally hauled in by a steam capstan, driven
by a small donkey engine. When the trawl comes alongside, the beam is
secured and the net is gradually hauled over the side by hand until
the cod end appears; this is then made fast to a rope and tackle,
and hauled above the deck. The cod line is untied and the fish are
discharged upon the deck.
Since trawling is generally carried out on smooth ground, the greater
proportion of the catch consists of certain kinds of demersal fishes
that frequent sand and gravel. Of these, the most important are cod,
haddock, whiting, ling, hake, catfish, sole, plaice, turbot, and brill.
Certain of these species also frequent rocky ground, and are taken in
such areas by the line fishermen.
Generally speaking, line fishermen work in deeper water than trawlers
and capture larger fish, though of fewer species, e.g. cod, halibut,
ling, skates and rays.
The original sailing trawlers are rapidly being superseded by steam
trawlers. The first steam trawling company was formed in 1882. It
had a capital of £20,000 and a fleet of four vessels. It trawled on
the Dogger Bank for three years with marked success. After this the
future of steam trawling was assured. The steam trawler is many times
more efficient than a smack, for it can fish in nearly all weathers,
including calm, and it can trawl over rough bottoms, owing to its
greater power, and can go much further afield.
[Illustration: FIG. 15
MODERN STEAM TRAWLER (SECTION)
Total length, 160 ft.
Length between perpendiculars, 148·5 ft.
Greatest breadth (frame), 23 ft.
Draught, 13-3/4 ft.
_Explanation of Section._—1. Wheelhouse. 2. Captain’s cabin. 3.
Collision bulkhead. 4. Crew’s quarters. 5. Store for gear, nets,
etc. 6. Chain locker. 7. Fish-pounds (on deck). 8. Fish-hold. 9.
Cross bunker (for coal). 10. Main bunker. 11. Passage to bunker.
12. Steam-winch. 13. Stokehold. 14. Lifeboat. 15. Triple expansion
engines (650 indicated h.p.). 16. Bathroom. 17. Mate’s quarters. 18.
Dining-room and berths for engineers. 19. Storeroom.]
Modern British steam trawlers travel as far afield as Iceland,
Newfoundland and Morocco.
Steam trawling developed rapidly, and resulted in a correspondingly
rapid decrease in the number of sailing trawlers. Between 1893 and
1903, the number of first class smacks in Great Britain decreased from
over 2,000 with an average tonnage (net) of 57·4 to less than 900 with
an average tonnage (net) of 40. From 1903 until the present day, the
number had remained between 900 and 800; it would seem, therefore,
that the relative numbers and importance of smacks and steam trawlers
gradually attained to a condition of equilibrium. Between 1900 and 1906
the increasing importance of steam trawling received a temporary check.
A steam trawler in those days would cost about £10,000 to construct and
about £5,000 a year to operate; their commercial success, therefore,
depended upon correspondingly large and valuable catches of fish being
obtained. When first introduced on the fishing grounds round the coast
their superior efficiency and speed amply compensated for their high
cost. About 1900, however, the catch obtained by these vessels on
the home fishing grounds began to diminish, and the fishermen became
alarmed lest the greatly increased efficiency of steam trawling should
prove to be its own undoing, and result in the depopulation of the
fishing grounds by over-fishing. Between 1900 and 1906, the number
of steam trawlers fishing from British ports only increased by 200,
whereas, during the preceding 10 years, the numbers had increased from
a few hundred to over 2,000.
The anticipated exhaustion of the home grounds led to the steam trawler
prospecting further afield. These longer voyages, as far as Iceland and
the White Sea and Morocco, were very successful. The result of this
was that larger steam trawlers were built, capable of undertaking
long voyages of many weeks’ duration. Between 1900 and 1906 the
average net tonnage of the steam trawlers increased from 54 to 62. The
steam trawlers, in opening up new and more distant fishing grounds,
left the home grounds to the smacks. Consequently we find that the
smacks confined their operation to the smooth ground in home waters,
leaving the rough and more distant grounds to the steam trawlers. A
direct result of this gradual redistribution of the fisheries between
sailing smacks and steamers was the development of specialized fishing
ports. Such ports as Lowestoft, Brixham and Ramsgate, off which good
fish are obtainable and which are within easy access of good markets,
have retained their importance as smack ports; on the other hand, the
development of steam trawling has led to the rapid growth of deep
water ports, such as Fleetwood, Grimsby, Hull, Aberdeen, and Milford
Haven. In Grimsby, originally one of the greatest strongholds of
smack fishing, smacks have been entirely displaced by steam trawlers,
owing to the special facilities which the port offers in being near
cheap coal, in possessing deep water, and in being in direct rail
communication with large markets for trawl fish.
There is no doubt that the rapid development of steam trawling was
accelerated by the invention of the otter trawl. This is not only a
larger net than the beam trawl, but is for all but small, flat fish,
a much more efficient instrument. From the study of market statistics
between the years 1889 and 1898 Garstang has calculated that a steamer
caught on the average between four and seven times as much fish in the
year as a sailing smack.
[Illustration: FIG. 16
I.—PLAN ON DECK.
II.—PLAN BELOW DECK.
_Plan of Arrangements on and below Deck._—(I) On deck: 1. Winch. 2.
Hatches. 3. Gallows. 4. Bollards. 5. Fish-pounds. 6. Steam-winch (for
trawl). 7. Blocks. 8. Officers’ messroom. 9. Galley. 10. Ventilators.
11. Funnel. 12. Bunker-hatches. 13. Engine-room skylight. 14.
Bathroom. 15. Mate’s cabin. 16. Lifeboat.
(II) Below deck: 1. Collision bulkhead. 2. Crew’s quarters. 3.
Storeroom. 4. Iceroom. 5. Fish-hold. 6. Reserve coal bunker. 7. Main
bunker. 8. Side bunkers. 9. Stokehold. 10. Main pump. 11. Auxiliary
pump. 12. Engines. 13. Dynamo. 14. Cabin. 15 and 16. Chief and second
engineers’ quarters.]
A modern steam trawler is from 150 to 160 ft. long by 25 ft. beam and
12 ft. depth, constructed with a high bow and a low, flat stern. Her
net tonnage is from 60 to 200, her bunker capacity 250 tons, with
storage room for up to 120 tons of fish. She is fitted with triple
expansion engines of from 40 to 85 horse power. The forward part of
the ship is occupied by the living quarters of the crew, rope and
net store, iceroom, and fish-hold. Larger vessels, making trips to
distant grounds, will take as much as 30 tons of broken ice; this ice
is distributed over the fish in layers, after they have been cleaned
and gutted. In practically all modern fishing ports there is a special
ice factory situated near the quay, and ice is manufactured by the
ammonia process, crushed, and delivered to the ships through zinc-lined
chutes. The fish-hold in the forward part of the ship extends right
across the ship and is from 9 to 10 ft. high, divided by a partition
into two compartments, each compartment fitted with two shelves 5 ft.
long, on which the fish are piled. These shelves reduce compression and
facilitate the storage of the fish, the front of each compartment being
closed with boards as it becomes full. She generally carries three or
four trawl nets, one on her starboard and the other on her port, one or
two being down below in reserve. The boat is fitted with four gallows,
two forward and two aft, one on each side of the boat. These gallows
are used for lifting the otter boards out of the water when the trawl
is hauled in.
The ship carries nine hands, consisting of skipper, mate, boatswain,
two deck hands, cook, two engineers and a fireman.
On the fishing grounds, fishing is continuous. The net is trawled for
from two to four hours, although on grounds where fish is plentiful
(e.g. Iceland) the trawl is frequently hauled every half-hour. It is
then hauled aboard, and the cod end containing the fish is swung over
the deck. The cod line is unfastened so that the cod end of the net
opens, and the fish are discharged into a pound formed on the deck by
horizontal 9″ × 3″ deal boards. The net is cleaned and shot again.
On smooth ground trawling is commercially possible at all depths down
to 300 fathoms. In few cases, however, is trawling carried on at
greater depths than 200 fathoms.
Owing to the large amount of stores and repairs, etc., connected
with the maintenance of a fleet of steam trawlers, most large owners
maintain fairly elaborate premises in the neighbourhood of the fish
dock. These premises generally consist of a net-making hall in which
nets are made by women working with shuttles, a large bath of tar or
tanning material below in which the net is soaked, also a wood yard
and blacksmith’s shop, containing a steam hammer, a plumber’s shop,
a boat-builder’s shop, a large store-room fitted with the necessary
stores and spares.
During the war the steam trawlers were commandeered by the Government
for use as patrol boats and mine sweepers. It is estimated that 10
per cent of our steam trawlers and drifters and their crews were lost
during the war.
[Illustration: FIG. 17
A.—The otter trawl.
B.—Attachment of board to net. OB. Otter board. B. Iron brackets.
C. Chain to connect with warps. M. Metal strengthening pieces. M′.
Iron shoe. HL. Head line. UW. Upper wing. LW. Lower wing. LL. Lacing
connecting wings. GR. Ground rope. D. Balch of lower wing. SSS. Twine
settings connecting balch to ground rope. A. Headline and lacing
connected to board by shackle. B. Toe of ground rope connected to
board by shackle.
C.—Bosom of a bobbin foot-rope for use on rough ground. AB. Balch
line on head of belly and connecting with bosom of wings. SS. Wire
seizings connecting balch to small intermediate bobbins, 6″ diameter
(EE). Large bobbins up to 24″ diameter (FF).]
When steam trawling was first introduced it aroused general
opposition, for there was not only the fear that their efficiency
would lead to over-fishing in certain grounds, but it was said that
the trawl, when dragged along the bottom, destroyed the eggs and
killed the immature fish. The line fisherman found that steam trawling
made it more difficult to catch demersal fish with baited hooks. He
attributed this to the effect of over-fishing, but it is probable that
contact with the otter trawls had made the fish rather more shy and,
therefore, more difficult to catch by this method. It is unlikely that
steam trawling will lead to serious over-fishing, except possibly
amongst such sedentary fish as soles and plaice. It must be remembered
that trawling is only commercially possible on comparatively smooth
ground and down to depths of about 200 fathoms. Probably, therefore,
the actual area trawled is only a small proportion of the total area
that is inhabited by fish. It is possible, of course, that extensive
and long continued trawling in a confined and relatively isolated area
may scare the fish away; it is probable, however, that any area in
which over-fishing appears to have produced temporary exhaustion will
tend to recover automatically, since it would naturally be abandoned
temporarily by the trawlers for more profitable fishing grounds.
There is no doubt that trawling, unless the size of the mesh is
carefully controlled, tends to remove large numbers of immature fish.
Generally in ordinary beam trawling—cod, plaice, haddock, etc.—the mesh
varies from 3 ins. diameter near the mouth of the net to about 1-1/4
ins. diameter at the cod end. If a much smaller mesh were used the
resistance encountered by a full-sized net would be so great that it
would be almost impossible to draw the net through the water. Smaller
trawls of 1/2 in. mesh are used in shallow coastal waters for catching
shrimps, small plaice and whiting. The size of mesh largely determines
the size of fish that will be retained by the net, since the smaller,
immature fish readily escape through the meshes. Of recent years the
various fishery boards, with a view to preventing the catching of such
small, immature fish, have increased the size of mesh that is to be
used—particularly when trawling within the three mile limit, where the
greatest proportion of immature fish is generally encountered. For
steam trawlers working in deep water a 2-1/2 in. mesh is generally
used, but within the three mile limit it is frequently increased from 3
to 3-1/2 ins.
[Illustration: FIG. 18
THE CATCH ABOARD]
Herring are caught with drift nets at night near the surface. In the
daytime they frequent the sea bottom and can then be caught with a
trawl net. Trawling for herrings was first practised by the fishermen
of Milford Haven and Fleetwood in 1901. They used an ordinary otter
trawl lined with a piece of herring net. A specially constructed
herring trawl is now used, of which the cod end is made of 2-1/2 in.
mesh instead of the usual 3-1/2 in.
When trawling for herrings the steamer goes at full speed, generally
for two to four hours, unless a shoal is encountered, when half-an-hour
is frequently sufficient.
Herrings are trawled in from 70 to 100 fathoms of water over a soft
bottom. The main centre for trawled herrings is North-West of Ireland,
other fisheries being carried on off the South-West of Ireland, the
West of Scotland, and in the North Sea. In 1913 over 500,000 cwts. of
herrings were taken with trawl nets in these areas.
This method of catching herrings aroused serious opposition among the
drift net fishermen. They asserted that the trawl catches and destroys
a high proportion of immature fish, and also destroys the herring eggs
as it passes along the sea bottom. In 1913 the matter was investigated
by a Parliamentary Committee, but any Government action was checked by
the outbreak of war.
Since 1905 the trawling grounds frequented by British steam trawlers
have been divided for statistical purposes into eighteen fishing areas.
The names and areas of these regions are shown in the chart of the
trawling grounds (Fig. 19).
Table I shows in hundredweights the average catch per day’s absence
from port in different areas.
[Illustration: FIG. 19
CHART
SHOWING
TRAWLING GROUNDS
Frequented by British Trawlers, the “Regions” into which they are
divided for statistical purposes, and the approximate area of each in
square miles (Nautical) calculated from the 3 mile limit to the 200
metre line.
NO. OF REGION. NAME. APPROX. AREA IN
SQ. MLS. NAUTICAL
I. White Sea 128,917
II. Coast of Norway 29,648
III. Baltic Sea 134,891
IV. North Sea 129,804*
V. North of Scotland 18,096
(Orkney and Shetland)
VI. Westward of Scotland 32,099
VII. Iceland 36,608
VIII. Faröe 4,949
IX. Rockall 3,430
X. West of Ireland 9,066
XI. Irish Sea 15,743
XII. Southward of Ireland 50,416
XIII. Bristol Channel 8,613
XIV. English Channel 25,238
XV. West of France 25,422
XVI. North of Spain 5,464
XVII. Coast of Portugal 9,997
XVIII. Coast of Morocco 10,499
-------
Total 678,900
-------
*_Excluding Area G, over 200 metres, and the Moray Firth_]
TABLE I
1906 1913 1920
White Sea 40·15 44·12 25·45
Iceland 44·22 46·10 58·54
Faröe 31·19 28·19 27·03
Rockall 38·98 39·27 49·53
North of Scotland 25·01 25·76 27·31
North Sea 17·60 14·08 24·94
English Channel 11·36 8·95 25·70
Irish Sea 15·66 11·94 18·79
Bristol Channel 13·15 13·98 26·38
West of Scotland 21·18 28·11 28·17
West of Ireland 21·48 30·22 25·87
South of Ireland 26·97 23·74 26·63
Biscay 15·98 13·22 18·73
Portugal and Morocco 6·55 13·81 19·29
In England and Wales more fish is landed by trawlers than by all
other methods of fishing combined. Trawl-caught fish—soles, plaice,
turbot, halibut, cod—are much more valuable than fish caught by drift
nets, e.g. herring and mackerel. In England and Wales, in 1913, the
weight of pelagic fish caught amounted to 389,262 tons, and of demersal
fish 418,038 tons. Although the quantity of the demersal fish was,
therefore, only little larger than of the pelagic fish, its value was
£7,463,003, compared with £2,531,979, the value of the pelagic fish.