page_title: Bottom trawling
section_title: History
hierarchical_section_title: Bottom trawling / History
caption_attribution_description: Ficha do Buque Nome do buque Lista Matrícula Folio PINO LADRA 3 LU-3 2-04 RBPCAG 2005LU000396 Estado Alta Porto base Celeiro Caladoiro/Tipo de pesca CALADERO NACIONAL ARRASTRE Artes ARRASTRE DE FONDO Ano construcción 2004 Data entrada en servicio 08/11/2004 Arqueo TRB 171,00 Arqueo GT 277,00 Eslora total 31.40 M. Eslora PP 25.17 M. Potencia 489.00 CV. Material casco Aceiro
context_page_description: Bottom trawling is trawling along the sea floor. 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 and semi-pelagic species such as cod, squid, shrimp, and rockfish.
  Trawling is done by a trawler, which can be a small open boat with only 30 hp or a large factory trawler with 10,000 hp. Bottom trawling can be carried out by one trawler or by two trawlers fishing cooperatively.
  Global catch from bottom trawling has been estimated at over 30 million tonnes per year, an amount larger than any other fishing method.
context_section_description: An early reference to fishery conservation measures comes from a complaint about a form of trawling dating from the 14th century, during the reign of Edward III. A petition was presented to Parliament in 1376 calling for the prohibition of a "subtlety contrived instrument called the wondyrchoum". This was an early beam trawl with a wooden beam, and consisted of a net 6 m (18 ft) long and 3 m (10 ft) wide,
  "of so small a mesh, no manner of fish, however small, entering within it can pass out and is compelled to remain therein and be taken...by means of which instrument the fishermen aforesaid take so great abundance of small fish aforesaid, that they know not what to do with them, but feed and fatten the pigs with them, to the great damage of the whole commons of the kingdom, and the destruction of the fisheries in like places, for which they pray remedy."
  Another source describes the wondyrchoum as
  "three fathom long and ten mens' feet wide, and that it had a beam ten feet long, at the end of which were two frames formed like a colerake, that a leaded rope weighted with a great many stones was fixed on the lower part of the net between the two frames, and that another rope was fixed with nails on the upper part of the beam, so that the fish entering the space between the beam and the lower net were caught.  The net had maskes of the length and breadth of two men’s thumbs"
  The response from the Crown was to "let Commission be made by qualified persons to inquire and certify on the truth of this allegation, and thereon let right be done in the Court of Chancery". Thus, already back in the Middle Ages, basic arguments about three of the most sensitive current issues surrounding trawling - the effect of trawling on the wider environment, the use of small mesh size, and of industrial fishing for animal feed - were already being raised.
  Until the late 18th century sailing vessels were only capable of towing small trawls. However, in the closing years of that century a type of vessel emerged that was capable of towing a large trawl, in deeper waters. The development of this type of craft, the sailing trawler, is credited to the fishermen of Brixham in Devon. The new method proved to be far more efficient than traditional long-lining. At first its use was confined to the western half of the English Channel, but as the Brixham men extended their range to the North Sea and Irish Sea it became the norm there too.
  By the end of the 19th century there were more than 3,000 sailing trawlers in commission in UK waters and the practice had spread to neighbouring European countries. Despite the availability of steam, trawling under sail continued to be economically efficient, and sailing trawlers continued to be built until the middle of the 1920s. Some were still operating in UK waters until the outbreak of World War II, and in Scandinavia and the Faroe Islands until the 1950s.
  English commissions in the 19th century determined that there should be no limitation on trawling.  They believed that bottom trawling, like tilling of land, actually increased production.  As evidence, they noted that a second trawler would often follow a first trawler, and that the second trawler would often harvest even more fish than the first.  The reason for this peculiarity is that the destruction caused by the first trawl resulted in many dead and dying organisms, which temporarily attracted a large number of additional species to feed on this moribund mass.
  Bottom trawling does not only have a long tradition in European waters. It was also recognized in 1704 during the Edo era in Japan as a common fishing method. A slightly different approach was developed where the “Utase Ami” or “trawled bottom net” was deployed from a sideways sailing boat.
  Bottom trawling has been widely implicated in the population collapse of a variety of fish species, locally and worldwide, including orange roughy, barndoor skate, shark, and many others.
caption: A bottom trawler at Viveiro in Spain
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