Fishing trawler

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medium fishing trawler Fishing Trawler.jpg
medium fishing trawler
The Irish RSW Pelagic Trawler Brendelen SO709 in Skagen harbour Trawler Skagen harbour.jpg
The Irish RSW Pelagic Trawler Brendelen SO709 in Skagen harbour
large fishing trawler Fishing Trawler (33193397000).jpg
large fishing trawler
Fishing intensity extracted from Automatic Identification System data of EU trawlers greater than 15 metres in length, in the period October 2014 - September 2015 (see Main Map for full resolution ) EU Trawlers.png
Fishing intensity extracted from Automatic Identification System data of EU trawlers greater than 15 metres in length, in the period October 2014 – September 2015 (see Main Map for full resolution )

A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. A trawler may also operate two or more trawl nets simultaneously (double-rig and multi-rig).

Contents

There are many variants of trawling gear. They vary according to local traditions, bottom conditions, and how large and powerful the trawling boats are. A trawling boat can be a small open boat with only 30  horsepower (22 kW) or a large factory ship with 10,000 horsepower (7457 kW). Trawl variants include beam trawls, large-opening midwater trawls, and large bottom trawls, such as "rock hoppers" that are rigged with heavy rubber wheels that let the net crawl over rocky bottom.

History

Painting of A Brixham trawler by William Adolphus Knell. The painting is now in the National Maritime Museum. A Brixham trawler.jpg
Painting of A Brixham trawler by William Adolphus Knell. The painting is now in the National Maritime Museum.

During the 17th century, the British developed the Dogger, an early type of sailing trawler commonly operated in the North Sea. The Dogger takes its name from the Dutch word dogger, meaning a fishing vessel which tows a trawl. [4] Doggers were slow but sturdy, capable of fishing in the rough conditions of the North Sea. [5]

The modern fishing trawler was developed in the 19th century, at the English fishing port of Brixham. By the early 19th century, the fishermen at Brixham needed to expand their fishing area further than ever before due to the ongoing depletion of stocks that was occurring in the overfished waters of South Devon. The Brixham trawler that evolved there was of a sleek build and had a tall gaff rig, which gave the vessel sufficient speed to make long-distance trips out to the fishing grounds in the ocean. They were also sufficiently robust to be able to tow large trawls in deep water. The great trawling fleet that built up at Brixham, earned the village the title of 'Mother of Deep-Sea Fisheries'.

This revolutionary design made large scale trawling in the ocean possible for the first time, resulting in a substantial migration of fishermen from the ports in the South of England, to villages further north, such as Scarborough, Hull, Grimsby, Harwich and Yarmouth, that were points of access to the large fishing grounds in the Atlantic Ocean. The small village of Grimsby grew to become the 'largest fishing port in the world' [6] by the mid 19th century. With the tremendous expansion in the fishing industry, the Grimsby Dock Company was opened in 1854 as the first modern fishing port. [7] The facilities incorporated many innovations of the time – the dock gates and cranes were operated by hydraulic power, and the 300-foot (91 m) Grimsby Dock Tower was built to provide a head of water with sufficient pressure by William Armstrong. [8]

The elegant Brixham trawler spread across the world, influencing fishing fleets everywhere. [9] [10] By the end of the 19th century, there were over 3,000 fishing trawlers in commission in Britain, with almost 1,000 at Grimsby. These trawlers were sold to fishermen around Europe, including from the Netherlands and Scandinavia. Twelve trawlers went on to form the nucleus of the German fishing fleet. [11]

Advent of steam power

The earliest steam-powered fishing boats first appeared in the 1870s and used the trawl system of fishing as well as lines and drift nets. These were large boats, usually 80–90 feet (24–27 m) in length with a beam of around 20 feet (6.1 m). They weighed 40–50 tons and travelled at 9–11 knots (17–20 km/h; 10–13 mph).

The earliest purpose-built fishing vessels were designed and made by David Allan in Leith in March 1875, when he converted a drifter to steam power. In 1877, he built the first screw-propelled steam trawler in the world. This vessel was Pioneer LH854. She was of wooden construction with two masts and carried a gaff-rigged main and mizen using booms, and a single foresail. Allan argued that his motivation for steam power was to increase the safety of fishermen. However local fishermen saw power trawling as a threat. Allan built a total of ten boats at Leith between 1877 and 1881. Twenty-one boats were completed at Granton, his last vessel being Degrave in 1886. Most of these were sold to foreign owners in France, Belgium, Spain and the West Indies. [12]

The first steam boats were made of wood, but steel hulls were soon introduced and were divided into watertight compartments. They were well designed for the crew with a large building that contained the wheelhouse and the deckhouse. The boats built in the 20th century only had a mizzen sail, which was used to help steady the boat when its nets were out. The main function of the mast was now as a crane for lifting the catch ashore. It also had a steam capstan on the foredeck near the mast for hauling nets. These boats had a crew of twelve made up of a skipper, driver, fireman (to look after the boiler) and nine deck hands. [12]

Steam fishing boats had many advantages. They were usually about 20 ft longer (6.1 m) than the sailing vessels so they could carry more nets and catch more fish. This was important, as the market was growing quickly at the beginning of the 20th century. They could travel faster and further and with greater freedom from weather, wind and tide. Because less time was spent travelling to and from the fishing grounds, more time could be spent fishing. The steam boats also gained the highest prices for their fish, as they could return quickly to harbour with their fresh catch. [12]

Steam trawlers were introduced at Grimsby and Hull in the 1880s. In 1890 it was estimated that there were 20,000 men on the North Sea. The steam drifter was not used in the herring fishery until 1897. The last sailing fishing trawler was built in 1925 in Grimsby.

Further development

Armed trawler HNoMS Honningsvag off Iceland. HNoMS Honningsvag.jpg
Armed trawler HNoMS Honningsvåg off Iceland.

Trawler designs adapted as the way they were powered changed from sail to coal-fired steam by World War I to diesel and turbines by the end of World War II.

The first trawlers fished over the side, rather than over the stern. In 1947, the company Christian Salvesen, based in Leith, Scotland, refitted a surplus Algerine-class minesweeper (HMS Felicity) with refrigeration equipment and a factory ship stern ramp, to produce the first combined freezer/stern trawler in 1947. [13]

The first purpose-built stern trawler was Fairtry built in 1953 at Aberdeen. The ship was much larger than any other trawlers then in operation and inaugurated the era of the 'super trawler'. As the ship pulled its nets over the stern, it could lift out a much greater haul of up to 60 tonnes. Lord Nelson followed in 1961, installed with vertical plate freezers that had been researched and built at the Torry Research Station. These ships served as a basis for the expansion of 'super trawlers' around the world in the following decades. [13]

Since World War II, commercial fishing vessels have been increasingly equipped with electronic aids, such as radio navigation aids and fish finders. During the Cold War, some countries fitted fishing trawlers with additional electronic gear so they could be used as spy ships to monitor the activities of other countries.

Modern trawlers

Modern trawlers are usually decked vessels designed for robustness. Their superstructure (wheelhouse and accommodation) can be forward, midship or aft. Motorised winches, electronic navigation and sonar systems are usually installed. Fishing equipment varies in sophistication depending on the size of the vessel and the technology used. Design features for modern fishing trawlers vary substantially, as many national maritime jurisdictions do not impose compulsory vessel inspection standards for smaller commercial fishing vessels. [14] [15]

Mechanised hauling

Mechanised hauling devices are used on modern trawlers. Trawl winches, such as Gilson winches, net drums [16] and other auxiliary winches are installed on deck to control the towing warps (trawling wires) and store them when not in use.

Electronics

Decca Navigator (Mark 21) and Decca Track Plotter (the forerunners of modern GPS navigation and plotting equipment) on the bridge of this (rather dated) trawler. Amandine31.jpg
Decca Navigator (Mark 21) and Decca Track Plotter (the forerunners of modern GPS navigation and plotting equipment) on the bridge of this (rather dated) trawler.

Modern trawlers make extensive use of contemporary electronics, including navigation and communication equipment, fish detection devices, and equipment to control and monitor gear. Just which equipment will be installed depends on the size and type of the trawler.

Much of this equipment can be controlled from the wheelhouse or bridge. Smaller trawlers have wheelhouses, where electronic equipment for navigation, communications, fish detection and trawl sensors are typically arranged about the skipper's chair. Larger vessels have a bridge, with a command console at the centre and a further co-pilot chair. Modern consoles display all the key information on an integrated display. Less frequently used sensors and monitors may be mounted on the deckhead. [17]

Navigational instruments, such as an autopilot and GPS, are used for manoeuvring the vessel in harbour and at sea. Radar can be used, for example, when pair trawling to keep the correct distance between the two vessels. Communication instruments range from basic radio devices to maritime distress systems and EPIRBs, as well as devices for communicating with the crew. Fish detection devices, such as echosounders and sonar, are used to locate fish. [17]

A net mensurations system using acoustic sensors which measure the depth and opening of the trawl net. Acoustic trawl sensors.jpg
A net mensurations system using acoustic sensors which measure the depth and opening of the trawl net.

During trawling operations, a range of trawl sensors may be used to assist with controlling and monitoring gear. These are often referred to as "trawl monitoring systems" or "net mensuration systems".

Automatic knives for filleting fish Fish processing hg.jpg
Automatic knives for filleting fish

Fish storage and processing

Modern trawlers store the fish they catch in some form of chilled condition. At the least, the fish will be stored in boxes covered with ice or stored with ice in the fish hold. In general, the fish are kept fresh by chilling them with ice or refrigerated sea water, or freezing them in blocks. Also, many trawlers carry out some measure of onboard fish processing, and the larger the vessel, the more likely it is to include fish processing facilities. For example, the catch can undergo some preliminary processing by being passed through sorting and washing devices. At a further stage, the fish might be mechanically gutted and filleted. Factory trawlers may process fish oil and fish meal and may include canning plants.

Other design features

Crew quarters are usually below the wheelhouse and may include bunks, with cot sides to stop the occupant from rolling out in heavy weather. The need for drying sea clothes is shown by a notice in at least one steam trawler's boiler room saying "Do not dry oil frocks over the boiler". [18]

Trawler types

Trawlers can be classified by their architecture, the type of fish they catch, the fishing method used, or geographical origin. The classification used below follows the FAO, who classify trawlers by the gear they use. [19]

Outrigger trawlers

Outrigger trawlers use outriggers, or booms, to tow the trawl. These outriggers are usually fastened to, or at the foot of the mast and extend out over the sides of the vessel during fishing operations. Each side can deploy a twin trawl or a single otter trawl. Outrigger trawlers may have the superstructure forward or aft. Warp winches with capstans are installed on the deck to haul the catch.

This small shrimp trawler uses outriggers, with a forward deckhouse and aft working deck. Trawer Hauling Nets.jpg
This small shrimp trawler uses outriggers, with a forward deckhouse and aft working deck.

Outrigger trawlers use vertical fish finders of different kinds, according to their size. [20] Drawing (FAO)

Beam trawlers

External image
Searchtool.svg A drawing of a beam trawler

Beam trawlers are a type of outrigger trawler (above), with the superstructure aft and the working deck amidships. They use a very strong outrigger boom on each side, each towing a beam trawl, with the warps going through blocks at the end of the boom. This arrangement makes it easier to stow and handle the large beams. The outriggers are controlled from a midship A-frame or mast. The towing winch is forward of the superstructure, with the towing warps passed through deck bollards and then out to the towing blocks on the booms.

Beam trawling is used in the flatfish fisheries in the North Sea. They are equipped with equipment for hauling the net and stowing it aboard. Typically an multibeam echosounder is used for finding fish.

They are medium-sized and high-powered vessels, towing gear at speeds up to 8 knots. To avoid the boat capsizing if the trawl snags on the sea floor, winch brakes can be installed, along with safety release systems in the boom stays. The engine power of bottom trawlers is restricted to 2000 HP (1472 kW) for further safety. [21]

Drawing of a large trawler.png

Otter trawlers

Otter trawlers deploy one or more parallel trawls kept apart horizontally using otter boards. These trawls can be towed in midwater or along the bottom. Otter trawlers range in size from sailing canoes to supertrawlers. [22]

Otter trawlers usually have two gallows at the stern with towing blocks. The towing warps run through these, each regulated by its own winch. Medium and large trawlers usually have a stern ramp for hauling the trawl onto the deck. Some trawlers tow twin parallel trawls, using three warps, each warp with its own winch. Some otter trawlers are also outrigger trawlers (above), using outriggers to tow one or two otter trawls from each side. [22]

Usually otter trawlers have the superstructure forward, though it can be aft or amidship. Gallows are on the stern quarters or there is a stern gantry for operating the otter boards. Pelagic trawlers can use fish pumps to empty the cod end. [22]

Pair trawlers

Pair trawlers are trawlers which operate together towing a single trawl. They keep the trawl open horizontally by keeping their distance when towing. Otter boards are not used. Pair trawlers operate both midwater and bottom trawls. [23]

The superstructure is forward or midships and the working deck aft. Pelagic trawlers can have fish pumps to empty the codend. [23]

Side trawlers

External image
Searchtool.svg A drawing of a side trawler

Side trawlers have the trawl deployed over the side with the trawl warps passing through blocks suspended from a forward gallow and another aft gallow. Usually the superstructure is towards the stern, the fish hold amidships, and the transversal trawl winch forward of the superstructure. A derrick may be a boom rigged to the foremast to help shoot the cod end from the side. Until the late 1960s, side trawlers were the most common deepsea boat used in North Atlantic fisheries. The 1950s side trawler, Ross Tiger is preserved in Grimsby. These trawlers were used for a longer period than other kinds of trawlers, but are now being replaced by stern trawlers. Some side trawlers still in use have been equipped with net drums. [24]

Stern trawlers

An Icelandic stern trawler. Togari.jpg
An Icelandic stern trawler.
RV Celtic Explorer, a bottom trawler used for research. RV Celtic Explorer, Galway Bay, Ireland.jpg
RV Celtic Explorer, a bottom trawler used for research.
External image
Searchtool.svg A drawing of a stern trawler

Stern trawlers have trawls which are deployed and retrieved from the stern. Larger stern trawlers often have a ramp, though pelagic and small stern trawlers are often designed without a ramp. Stern trawlers are designed to operate in most weather conditions. They can work alone when midwater or bottom trawling, or two can work together as pair trawlers. The superstructure is forward with an aft working deck. At the stern are gallows or a gantry for operating otter boards. [25]

Any fish processing usually occurs in deck houses or below deck. A wet fish stern trawler stores the fish in ice or sea water which has been refrigerated. A freezer stern trawler stores the fish in frozen boxes or blocks, and a factory stern trawler processes the catch. A pelagic stern trawler may use fish pumps to empty the codend. [25]

Freezer trawlers

The majority of trawlers operating on the high seas are freezer trawlers. They have facilities for preserving fish by freezing, allowing them to remain at sea for extended periods of time. They are medium- to large-size trawlers, with the same general arrangement as stern or side trawlers. [26] Drawing (FAO)

Wet fish trawlers

External image
Searchtool.svg A drawing of a wet fish trawler

Wet fish trawlers are trawlers where the fish are kept in the hold in a fresh/wet condition, in boxes covered with ice or with ice in the fish hold. They must operate in areas close to their landing place, and the time such a vessel can spend fishing is limited. [27]

Trawler/purse seiners

Trawler/purse seiners are designed so the deck equipment, including an appropriate combination winch, can be rearranged and used for both methods. Blocks, purse davits, trawl gallows and rollers need to be arranged so they control the pursing lines and warp leads and in such a way as to reduce the time required to convert from one arrangement to the other. These vessels are usually classified as trawlers, since the power requirement for trawling is higher. [28]

During both World Wars some countries created small warships by converting and arming existing trawlers or building new vessels to standard trawler designs. They were typically armed with a small naval gun and sometimes depth charges, and were used for patrolling, escorting other vessels and minesweeping.

Safety

Occupational safety is a concern on fishing trawlers. For example, a United States cooperative which operates a fleet of 24 bottom trawlers in Alaskan water reported 25 fatalities over the period 2001–2012. The risk of a fatal injury was 41 times higher than the average for workers in the United States. [29]

See also

Related Research Articles

Fishing Activity of trying to catch fish

Fishing is the activity of trying to catch fish. Fish are often caught in the wild but may also be caught from stocked bodies of water. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping. "Fishing" may include catching aquatic animals other than fish, such as molluscs, cephalopods, crustaceans, and echinoderms. The term is not normally applied to catching farmed fish, or to aquatic mammals, such as whales where the term whaling is more appropriate. In addition to being caught to be eaten, fish are caught as recreational pastimes. Fishing tournaments are held, and caught fish are sometimes kept as preserved or living trophies. When bioblitzes occur, fish are typically caught, identified, and then released.

Trawling Method of catching fish; principle by which netting bags are being towed in water to catch different species of fishes in their path

Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different species of fishes or sometimes targeted species. Trawls are often called towed gear or dragged gear.

Bottom trawling Fishing method for fishing trawlers

Bottom trawling is trawling along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the benthic zone. Bottom trawling can be contrasted with midwater trawling, where a net is towed higher in the water column. Midwater trawling catches pelagic fish such as anchovies, and mackerel, whereas bottom trawling targets both bottom-living fish (groundfish) and semi-pelagic species such as cod, squid, shrimp, and rockfish.

Midwater trawling is trawling, or net fishing, at a depth that is higher in the water column than the bottom of the ocean. It is contrasted with bottom trawling. Midwater trawling is also known as pelagic trawling and bottom trawling as benthic trawling.

Seine fishing Method of fishing with a net

Seine fishing is a method of fishing that employs a fishing net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.

Pair trawling

Pair trawling is a fishing activity carried out by two boats, with one towing each warp. As the mouth of the net is kept open by the lateral pull of the individual vessels, otter boards are not required. With the towing power of two boats and no otter boards, a larger net may be worked than would otherwise be possible, or alternatively, the two boats can share increased fuel efficiency.

The Scottish east coast fishery has been in existence for more than a thousand years, spanning the Viking Age right up to the present day.

Fishing vessel Boat or ship used to catch fish on a body of water

A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing.

Factory ship Oceangoing fish processing vessel

A factory ship, also known as a fish processing vessel, is a large ocean-going vessel with extensive on-board facilities for processing and freezing caught fish or whales. Modern factory ships are automated and enlarged versions of the earlier whalers and their use for fishing has grown dramatically. Some factory ships are equipped to serve as a mother ship.

History of fishing

Fishing is a prehistoric practice dating back at least 40,000 years. Since the 16th century, fishing vessels have been able to cross oceans in pursuit of fish, and since the 19th century it has been possible to use larger vessels and in some cases process the fish on board. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping.

<i>Mincarlo</i> (trawler)

Mincarlo is the last surviving sidewinder fishing trawler of the Lowestoft fishing fleet. She is also the last surviving fishing vessel built in Lowestoft, with an engine made in the town.

Traditional fishing boat

Traditionally, many different kinds of boats have been used as fishing boats to catch fish in the sea, or on a lake or river. Even today, many traditional fishing boats are still in use. According to the United Nations Food and Agriculture Organization (FAO), at the end of 2004, the world fishing fleet consisted of about 4 million vessels, of which 2.7 million were undecked (open) boats. While nearly all decked vessels were mechanised, only one-third of the undecked fishing boats were powered, usually with outboard engines. The remaining 1.8 million boats were traditional craft of various types, operated by sail and oars.

RV <i>Vantuna</i>

The Vantuna was a marine research vessel that operated in the Southern California Bight, from 1969 until 2007. It served as a tool for coastal research and was a unique platform for Occidental College students to gain first-hand experience conducting marine research operations. Scores of students who have worked on the Vantuna have gone on to have careers in marine science.

ST <i>Koraaga</i> (1914)

Koraaga was a Castle class steel-hulled trawler built in 1914 by Smiths Dock Company, South Bank, Middlesbrough. She was requisitioned as an auxiliary minesweeper operated by the Royal Australian Navy (RAN) in October 1917 for minesweeping duties during World War I, but she was never commissioned. Koraaga returned to be operated commercially as a fishing trawler until she wrecked when she struck a reef off Bass Point whilst carrying returning to Sydney. She was refloated on the tide after having becoming stranded and drifted till she was finally lost 5 miles east of Black Head, Gerringong New South Wales on 10 September 1931.

Ross Tiger

Ross Tiger is a traditional side-winder fishing trawler that was converted into a museum ship in 1992. She is currently berthed in Alexandra Dock at her home port of Grimsby, close to the site of the former PS Lincoln Castle. She forms the star attraction of North East Lincolnshire County Council's National Fishing Heritage Centre since restored and opened to the public in 1992. As Grimsby's last traditional sidewinder 'conventional trawler', she represents a now virtually extinct breed of vessels that once made up the largest fishing fleet in the world.

NOAAS <i>Bell M. Shimada</i> (R 227)

NOAAS Bell M. Shimada is an American fisheries research ship in commission with the National Oceanic and Atmospheric Administration (NOAA) since 2010. She operates along the United States West Coast.

NOAAS <i>Reuben Lasker</i> (R 228) American fisheries research vessel

NOAAS Reuben Lasker is a National Oceanic and Atmospheric Administration (NOAA) fishery research vessel. The ship's namesake, Reuben Lasker, was a fisheries biologist who served with the Southwest Fisheries Center, National Marine Fisheries Service, and taught at the Scripps Institution of Oceanography. This class of NOAA ships is very similar to, and based in part upon, the Neil Armstrong-class Oceanographic Research (AGOR) ships owned by the Office of Naval Research and operated by various US Universities.

The following outline is provided as an overview of and topical guide to the fishing industry:

Brixham trawler

A Brixham trawler is a type of wooden, deep-sea fishing trawler first built in Brixham in Devon, England, in the 19th century and known for its high speed. The design was copied by boat builders around Britain, and some were sold to fishermen in other countries on the North Sea.

NOAAS <i>Pisces</i> (R 226)

NOAAS Pisces is an American fisheries and oceanographic research vessel in commission in the National Oceanic and Atmospheric Administration (NOAA) fleet since 2009.

References

  1. F/V Brendelen Vessel details and current position.
  2. Vespe, Michele; Gibin, Maurizio; Alessandrini, Alfredo; Natale, Fabrizio; Mazzarella, Fabio; Osio, Giacomo C. (30 June 2016). "Mapping EU fishing activities using ship tracking data". Journal of Maps. 0: 520–525. arXiv: 1603.03826 . doi:10.1080/17445647.2016.1195299. ISSN   1744-5647. S2CID   7561749.
  3. Main Map of fishing activities In: Vespe, M., Gibin, M., Alessandrini, A., Natale, F., Mazzarella, F. and Osio, G.C. (2016) "Mapping EU fishing activities using ship tracking data". Journal of Maps, 12(sup1): 520–525. doi : 10.1080/17445647.2016.1195299.
  4. Oxford Companion to Ships and the Sea, p. 256
  5. Fagan 2008
  6. Days out: “Gone fishing in Grimsby” [ dead link ] The Independent , 8 September 2002
  7. "A brief history of Grimsby". localhistories.org.
  8. "Great Grimsby". UK Genealogy Archives.
  9. "History of a Brixham trawler". JKappeal.org. 2 March 2009. Archived from the original on 2 December 2010. Retrieved 13 September 2010.
  10. "Pilgrim's restoration under full sail". BBC. Retrieved 2 March 2009.
  11. Sailing trawlers.
  12. 1 2 3 "The Steam Trawler".
  13. 1 2 "HISTORY". Archived from the original on 2013-08-21. Retrieved 2015-07-05.
  14. "Navigation and Vessel Inspection Circular 5-86: Voluntary Standards for U.S. Uninspected Commercial Fishing Vessels" (PDF). United States Coast Guard. August 1986. Retrieved 2008-08-25.
  15. "Survey and Vessel Registration". Maritime Authority of New South Wales. 2008. Archived from the original on 2008-07-21. Retrieved 2008-08-25.
  16. Net drums FAO.
  17. 1 2 FAO: Fishing equipment
  18. In the National Fishing Heritage Centre at Grimsby
  19. FAO: Technology Fact Sheets: Fishing Vessel type
  20. FAO: Fishing Vessel type: Outrigger trawlers
  21. FAO: Fishing Vessel type: Beam trawlers
  22. 1 2 3 FAO: Fishing Vessel type: Otter trawlers
  23. 1 2 FAO: Fishing Vessel type: Pair trawlers
  24. FAO: Fishing Vessel type: Side trawlers
  25. 1 2 FAO: Fishing Vessel type: Stern trawlers
  26. FAO: Fishing Vessel type: Freezer trawlers
  27. FAO: Fishing Vessel type: Wet-fish trawlers
  28. FAO: Fishing Vessel type: Trawler-purse seiners
  29. "Five-year review of the effects of Amendment 80" North Pacific Fishery Management Council, October 2014, pp.45–53.