When the fishing industry was in its infancy the main method used to catch fish was the ‘beam trawl’ towed by sailing smacks. This net had the mouth held open by a large wooden beam. Because the smacks were dependent on the wind for their towing power, the weight of this beam imposed limits on the size of the net that they could use. The breakthrough came in 1894 when the trawler Otter began using ‘kites’ instead of the beam. The name of the trawler soon became synonymous with the kites and they were universally known as ‘Otter doors or boards’. The introduction of the Otter board meant that the weight of the trawl could be substantially reduced and larger nets could be employed.

The Demersal Trawl

Legend

A. The wings of the trawl
B. The square
C. The Belly
D. Lower Belly
E & F. Lengthener and false lengthener
G. The cod end where the fish were concentrated. This was protected from sea floor abrasion by cow hides
1. Trawl warp connecting the net to the trawler
2. The otter doors that hold the net open in a lateral direction
3. The swivel links
4. G link
5. 5Triangular mounting brackets
6. Steel shoe to prevent sea floor abrasion of the wooden door
7. Back strop
8. Independent piece
9. Kelly’s eye
10. Cable
11. Swivel
12. Dan Leno bobbin which, I was always told, was named after the comedian for some obscure reason
13. Butterfly
14. Headline leg
15. Toeline leg
16. Wing line
17. Quarter rope
18. Headrope floats. Once made from glass and much prized by restaurants as ornaments, these were replaced with aluminium items as fishing depths increased. Their job was to hold the net open in a vertical direction
19. Ground rope or footrope
20. Rubber wing bobbins. Often made from rings stamped out of rubber tyres to protect the wing rope
21. Headline becket
22. Wire bellyline
23. Iron bobbins.These were also made of wood and were threaded onto the footrope to allow the trawl to roll across the sea bed. The vibration that these set up would also serve the purpose of frightening the fish into the net
24. Rope bellyline
25. Poke line
26. Hauling leg
27. Double bag beckett. Used when the net held too much fish to bring inboard at once
28. Cow hides to prevent the cod end chafing
29. Cod line

The Prey

British fishermen have, traditionally, sought many species of fish, some of which can only be considered a local delicacy and eaten nowhere else. The main species that are recognised everywhere are cod, hake and haddock.

Cod is a common name for nearly 60 species of a family of valuable food fishes. Other families in the same order are also known as cod, such as the deep-sea cod, but the best-known and most commercially important cod is the Atlantic cod. Cod live chiefly in cold or temperate northern seas, at depths of 180 to 360 m (600 to 1200 ft), and undertake long migrations. Many live near the bottom. The Atlantic cod has three dorsal fins, two anal fins, an unforked tail, and a small barbel on its lower jaw. It is generally moderate in size but can weigh as much as 90 kg (200 lb) and be as long as 1.8 m (6 ft). Greenish-gray to blackish-brown and sometimes red, it has a marbled pattern on its head, back, and sides.

It is a voracious predator, eating herring, sand eel, and other shoal fishes. The cod gather in large numbers during the winter months to spawn, and each female lays 4 million to 7 million eggs. The eggs of some species have a droplet of oil so that they float, and these larval cod become part of the plankton for about ten weeks. They sink to the bottom when they are about 2 cm (about 1 in) long, begin to migrate in the second year, and spawn in five years.

Cod are valued both as food and as the source of cod-liver oil. They form the basis of a historically profitable fishery in the North Atlantic, to which England, France, and Portugal began to send boats yearly in the 16th century. The crews camped on the beaches during their stay and dried the fish before sending their catch back to Europe. Such fishing is still an important part of the economy in countries such as Iceland and Great Britain. Thinning of the fish stocks has made the remaining sources vital enough to cause aggressive competition.

Other commercially important species of cod include the pollock; the walleye pollock; the Pacific cod, greatly valued by the Japanese; the haddock; and the tomcod genus. Haddock, in particular, have been overfished by large stern-trawling factory ships. Scientific classification: Cod belong to the family Gadidae, of the order Gadiformes. Deep-sea cod make up the family Moridae. The Atlantic cod is classified as Gadus morhua, the pollock as Pollachius virens, the walleye pollock as Theragra chalcogramma, the Pacific cod as Gadus macrocephalus, and the haddock as Melanogrammus aegelfinus. Tomcods are classified in the genus Microgadus.

Haddock are bottom-feeding marine fish of the cod family, differing from the cod in its smaller mouth, longer anterior dorsal fin, and the black line that runs along its side. It is usually about 60 cm (about 24 in) long and has a brown back and silvery underside; a black spot is located on each side behind the gills. The haddock travels in large schools and is abundant in the North Atlantic Ocean from Iceland to Cape Hatteras. It feeds mainly on small invertebrates. It is frequently sold smoked (under the name finnan haddie) or dried. Scientific classification: The haddock belongs to the family Gadidae. It is classified as Melanogrammus aeglefinus.

Hake is the common name for any of several related soft-rayed, marine, acanthopterygian fishes. All hakes are carnivorous. Certain hakes called codlings are found on both sides of the North Atlantic Ocean and are characterized by filamentous, narrow pelvic fins attached to the throat and trailing in the water. This feature has led to the English name forkbeard for the common European species, also known as hake’s dame. The red hake is the common American species and is about 60 cm (about 24 in) long. This fish and the white hake are sought for their oil and for their air bladders, used in making isinglass.

The true hakes are found on both sides of the Atlantic Ocean, in the Mediterranean Sea, and in the Pacific Ocean, off the United States, Chile, and New Zealand. The common European hake is slender, reaching 1.2 m (4 ft) in length, with a long, pointed snout.

Scientific classification: The hakes known as codlings belong to the family Gadidae and are classified in the genus Urophycis. The forkbeard is classified as Urophycis blennoides, the red hake as Urophycis chuss, and the white hake as Urophycis tenuis. True hakes make up the family Merlucciidae. The common European hake is classified as Merluccius merluccius, and the silver hake as Merluccius bilinearis.

The Flounder any of several flatfish having both eyes on one side of the body. This exposed side, as the fish lie on their side on the ocean bottom, is the left side in one family of flounders and, almost always, the right side in the other family. The body is flat, with scales present in some species and absent in others; the body is colored only on the exposed side. The families include such fishes as the halibut, turbot, and dab. All flounders are valued as food fishes. Several of the common species are called flukes. In the United States the most important species of flounder is the summer flounder, also called plaice and deep-sea flounder, which is found in the Atlantic Ocean from Massachusetts to Florida. The adult summer flounder may grow to a length of about 1 m (about 3 ft) and a weight of about 7 kg (about 15 lb). It feeds on small marine animals, such as shrimp, crab, and small fish. Large quantities of these fish are captured between May and October. The winter flounder, or lemon sole, and the fourspot flounder are found along the South Atlantic coast and in the Gulf of Mexico. The diamond turbot, found along the Pacific coast, is another common species. The plaice of western Europe grows to 60 cm (24 in) and 4.5 kg (10 lb). Two species of flounder are found along the coasts of Great Britain. Several other species are found in Arctic waters.

Skate known in the north west as the roker, is the common name applied to any member of a family of flat-bodied rays found in warm and temperate seas, including the coastal waters of the United Kingdom. The flesh of the European, or gray, skate, which attains a weight of 45 kg (100 lb), is extensively eaten in Europe; skate flesh is not common in the American diet. The smallest and commonest of the skates found along the eastern coast of North America is the little, or hedgehog, skate, which attains a length of less than 60 cm (less than 2 ft) and is densely spotted with black on its upper surface. The winter skate closely resembles the hedgehog skate but is somewhat larger and somewhat lighter in color. Another common skate of the American Atlantic coast is the smooth, or barn-door, skate, which attains a length of about 1 m (about 3.5 ft). The big skate, found off the coast of California, is the largest of the American skates, attaining a length of about 2 m (about 7 ft); the egg cases deposited by the female are almost 30 cm (almost 1 ft) long. Scientific classification: Skates make up the family Rajidae of the order Rajiformes. The European, or gray, skate is classified as Raja batis, the little, or hedgehog, skate as Raja erinacea, the winter skate as Raja diaphanes, the smooth, or barn-door, skate as Raja laevis, and the big skate as Raja binoculata.

Herring common name for several fishes characterized by a single short dorsal fin in the middle of the upper margin of the body and by an anal fin similarly located below. The head is scaleless, and the slender body is covered with thin, cycloid scales in which rings of organic material, rich in guanine (see Guano), are laid down each season. By counting these rings scientists can determine the age of the fish, which may live up to 20 years.

Herrings are economically the most important group of fish to North America and western Europe. The 199 species of the most widespread family include the menhaden, the pilchard (the young of which are common sardines), and the shad. They are saltwater fishes abundant throughout the North Atlantic Ocean, in the North and Baltic seas, and in the North Pacific Ocean. Most swim near the surface of the water in huge schools and feed on plankton. They are about 30 cm (about 12 in) long when mature. The denticle herring is a freshwater fish inhabiting rivers in southwestern Nigeria. The wolf herring has fanglike teeth and preys on other fish; it is found in the Indian Ocean and the Western Pacific.

Spawning activity is quite varied. Some, such as the American shad, migrate into rivers and spawn in fresh water. Others, such as the Pacific sardine, spawn offshore in spring and summer and have eggs that float at the surface. The Pacific herring and the Atlantic herring spawn in shallow bays and deposit their eggs on seaweeds and shells. Herrings mature at three to four years of age in the North Sea, at five to eight in the Baltic Sea, and even later in the Bering Sea. Herrings of southerly seas die at an earlier age; consequently, those found in the north grow to a larger size.

The term herring, when unqualified, usually refers to the Atlantic herring. This fish, abundant in the Atlantic Ocean and found along the coast of the United States north of South Carolina, grows to a length of 30 cm (12 in) and is bluish-green above, silvery below. The young, and the young of the European sprat, are often called whitebait and are considered table delicacies. The Pacific herring, found from Alaska to Mexico, is a similar fish. The fall herring, so called because it spawns in the fall, is found south of Cape Cod; it is sometimes called hickory shad. The blueback, also known as the summer or glut herring, ascends into fresh water to spawn. Another common herring is the spring herring, or alewife.

The name herring is also applied to several freshwater fishes, such as the lake herring, or cisco, of the Great Lakes, and the rainbow herring, a smelt. The chimera, an ocean fish, is sometimes called king of the herrings. Herrings are important ecologically because they are a direct link in the food chain between tiny plankton and large marine predators. Plankton is consumed by the herring, which then become a food source for sharks, sea lions, birds, crabs, seals, whales and humans. The fishing, processing, and marketing of different species of the herring family is a major industry in the United States, Great Britain, Norway, Denmark, the Netherlands, Germany, France, and Portugal. Besides fresh and salted herring, the products of this industry on the market include red herring, which has been smoked until it is hardened; kippered herring, which is slightly salted and partially smoked; bloaters, which are large herrings that are heavily salted and partially smoked; and canned sardines.

Scientific classification: Herrings belong to the order Clupeiformes. The menhaden, pilchard, and shad belong to the family Clupeidae. The denticle herring belongs to the family Denticipitidae. The wolf herring makes up the family Chirocentridae. The American shad is classified as Alosa sapidissima. The Pacific sardine is classified as Sardinops sagax. The Pacific herring is classified as Clupea harengus pallasi, and the Atlantic herring is classified as Clupea harengus harengus. The European sprat is classified as Clupea sprattus. The fall herring is classified as Alosa mediocris, the blueback is classified as Alosa aestivalis, and the spring herring is classified as Alosa pseudoharengus.