![RV Celtic Explorer, Galway Bay, Ireland](https://upload.wikimedia.org/wikipedia/commons/b/bd/RV_Celtic_Explorer%2C_Galway_Bay%2C_Ireland.jpg)
Bottom trawling is
trawling
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 spec ...
(towing a trawl, which is a
fishing net
A fishing net is a Net (device), net used for fishing. Nets are devices made from fibers woven in a grid-like structure. Some fishing nets are also called fish traps, for example #Fyke nets, fyke nets. Fishing nets are usually meshes formed by ...
) 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
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 ...
(also known as
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...
trawling), where a net is towed higher in the
water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
. Midwater trawling catches
pelagic fish
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that do live on or near the bottom, and reef fish that are associated with coral re ...
such as
anchovies
An anchovy is a small, common forage fish of the family Engraulidae. Most species are found in marine waters, but several will enter brackish water, and some in South America are restricted to fresh water.
More than 140 species are placed in 1 ...
and
mackerel, whereas bottom trawling targets both bottom-living fish (
groundfish
Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They oc ...
) and semi-pelagic species such as
cod
Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...
,
squid,
shrimp, and
rockfish
Rockfish is a common term for several species of fish, referring to their tendency to hide among rocks.
The name rockfish is used for many kinds of fish used for food. This common name belongs to several groups that are not closely related, and ca ...
.
Trawling is done by a
trawler, which can be a small open boat with only or a large factory trawler with . Bottom trawling can be carried out by one trawler or by two trawlers fishing cooperatively (
pair trawling
Pair trawling is a fishing activity carried out by two boats, with one towing each warp (the towing cables). 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 powe ...
).
Global catch from bottom trawling has been estimated at over 30 million tonnes per year, an amount larger than any other fishing method. Concerns about the environmental impacts of bottom trawling have led to changes in gear design, such as the addition of
turtle excluder devices to reduce
bycatch, and limitations on locations where bottom trawling is allowed, such as
marine protected area
Marine protected areas (MPA) are protected areas of seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a conse ...
s. Moreover, a 2021 paper estimated that bottom trawling contributed between 600 and 1500 million tons of carbon dioxide a year by disturbing carbon dioxide in the sea floor – emissions approximately equivalent to
those of Germany, or
the aviation industry.
International attempts to limit bottom trawling have been ineffective.
History
![Pino Ladra 29](https://upload.wikimedia.org/wikipedia/commons/4/4b/Pino_Ladra_29.jpg)
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 modern politics, and history, a parliament is a legislative body of government. Generally, a modern parliament has three functions: representing the electorate, making laws, and overseeing the government via hearings and inquiries. Th ...
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 men's 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
The Court of Chancery was a court of equity in England and Wales that followed a set of loose rules to avoid a slow pace of change and possible harshness (or "inequity") of the common law. The Chancery had jurisdiction over all matters of equ ...
". 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
The orange roughy (''Hoplostethus atlanticus''), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). The UK Marine Conservation Society has categori ...
,
barndoor skate
The barndoor skate (''Dipturus laevis'') is a species of marine cartilaginous fish in the skate family Rajidae of the order Rajiformes. It is native to the northwestern Atlantic Ocean, and is found from the Grand Banks of Newfoundland and the ...
,
shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...
, and many others.
Fishing gear
The design requirements of a bottom trawl are relatively simple, a mechanism for keeping the mouth of the net open in horizontal and vertical dimensions, a "body" of net which guides fish inwards, and a "cod-end" of a suitable mesh size, where the fish are collected. The size and design of net used is determined by the species being targeted, the engine power and design of the fishing vessel and locally enforced regulations.
Beam trawling
File:FMIB 36649 Beam Trawl.jpeg, A beam trawl
File:FMIB 34023 Grampus.jpeg, A detail
The simplest method of bottom trawling, the mouth of the net is held open by a solid metal beam, attached to two "shoes", which are solid metal plates, welded to the ends of the beam, which slide over and disturb the seabed. This method is mainly used on smaller vessels, fishing for
flatfish or
prawn
Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten.
The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature' ...
s, relatively close inshore.
Otter trawling
![FMIB 36645 Otter trawl](https://upload.wikimedia.org/wikipedia/commons/5/56/FMIB_36645_Otter_trawl.jpeg)
Otter trawling derives its name from the large rectangular otter boards which are used to keep the mouth of the trawl net open. Otter boards are made of timber or steel and are positioned in such a way that the hydrodynamic forces, acting on them when the net is towed along the seabed, push them outwards and prevent the mouth of the net from closing. They also act like a
plough, digging up to into the seabed, creating a
turbid
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality.
Fluids can ...
cloud, and scaring fish towards the net mouth.
The net is held open vertically on an otter trawl by
float
Float may refer to:
Arts and entertainment Music Albums
* ''Float'' (Aesop Rock album), 2000
* ''Float'' (Flogging Molly album), 2008
* ''Float'' (Styles P album), 2013
Songs
* "Float" (Tim and the Glory Boys song), 2022
* "Float", by Bush ...
s and/or kites attached to the "headline" (the rope which runs along the upper mouth of the net), and weighted "bobbins" attached to the "foot rope" (the rope which runs along the lower mouth of the net). These bobbins vary in their design depending on the
roughness of the sea bed which is being fished, varying from small rubber discs for very smooth, sandy ground, to large metal balls, up to in diameter, for very rough ground. These bobbins can also be designed to lift the net off the seabed when they hit an obstacle. These are known as "rock-hopper" gear.
Body of the trawl
![Pelagisches Schleppnetz](https://upload.wikimedia.org/wikipedia/commons/e/e5/Pelagisches_Schleppnetz.jpg)
The body of the trawl is funnel-like, wide at its "mouth" and narrowing towards the cod end, and usually is fitted with wings of netting on both sides of the mouth. It is long enough to assure adequate flow of water and prevent fish from escaping the net, after having been caught. It is made of diamond-meshed netting, the size of the meshes decreasing from the front of the net towards the codend. Into the body, fish and turtle escape devices can be fitted. These can be simple structures like "square mesh panels", which are easier for smaller fish to pass through, or more complicated devices, such as
bycatch grills.
Cod end
The cod end is the trailing end of the net where fish are finally "caught". The size of mesh in the cod end is a determinant of the size of fish which the net catches. Consequently, regulation of mesh size is a common way of managing
mortality of
juvenile fishes in trawl nets.
How trawls work
The idea that fish are passively "scooped up" is commonly held, and has been since trawling was first developed, but has been revealed to be erroneous. Since the development of
scuba diving
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface air supply. The name "scuba", an acronym for " Self-Contained Underwater Breathing Apparatus", was coined by Chr ...
equipment and cheap
video camera
A video camera is an optical instrument that captures videos (as opposed to a movie camera, which records images on film). Video cameras were initially developed for the television industry but have since become widely used for a variety of oth ...
s it has been possible to directly observe the processes that occur when a trawl is towed along the seabed.
The trawl doors disturb the sea bed, create a cloud of muddy water which hides the oncoming trawl net and generates a noise which attracts fish. The fish begin to swim in front of the net mouth. As the trawl continues along the seabed, fish begin to tire and slip backwards into the net. Finally, the fish become exhausted and drop back, into the "cod end", and are caught.
The speed that the trawl is towed at depends on the swimming speed of the species which is being targeted and the exact gear that is being used, but for most
demersal species, a speed of around 4
knot
A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a ''hitch'' fastens a rope to another object; a ' ...
s (7 km/h) is appropriate.
Environmental damage
Trawling gear produces acute impacts on biota and the physical substratum of the seafloor by disrupting the sediment column structure, overturning boulders, re-suspending sediments and imprinting deep scars on muddy bottoms. Also, the repetitive passage of trawling gear over the same areas creates long-lasting, cumulative impacts that modify the cohesiveness and texture of sediments. It can be asserted nowadays that due to its recurrence, mobility and wide geographical extent, industrial trawling has become a major force driving seafloor change and affecting not only its physical integrity on short spatial scales but also imprinting measurable modifications to the geomorphology of entire continental margins.
[Oberle et al. (2018)]
“Submarine Geomorphology: Bottom Trawling and other Fishing Activities”
Book: Submarine Geomorphology Chapter 25, Springer, doi: 10.1007/978-3-319-57852
Bottom fishing has operated for over a century on heavily fished grounds such as the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...
and
Grand Banks
The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordf ...
. While
overfishing has long been recognised as causing major ecological changes to the fish community on the Grand Banks, concern has been raised more recently about the damage which benthic trawling inflicts upon seabed communities. A species of particular concern is the slow growing, deep water
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
''
Lophelia pertusa''. This species is home to a diverse community of deep sea organisms, but is easily damaged by fishing gear. On 17 November 2004, the
United Nations General Assembly
The United Nations General Assembly (UNGA or GA; french: link=no, Assemblée générale, AG) is one of the six principal organs of the United Nations (UN), serving as the main deliberative, policymaking, and representative organ of the UN. Curr ...
urged nations to consider temporary bans on high seas bottom trawling. A global analysis of the impacts of bottom trawling found that the impact on seabed
biota was strongly dependent on the type of gear used, with otter trawls estimated as having the smallest impact and removing 6% of biota per pass while hydraulic dredges had the largest impact and removed 41% of biota per pass. Other research found trawled canyon sediments contained 52 percent less organic matter than the undisturbed seafloor. There were 80 percent fewer sea worms in the trawled region and only half as much diversity of species in the trawled seafloor.
Resuspension and biogeochemistry
Bottom trawling stirs up the sediment at the bottom of the sea. The
suspended solid plumes can drift with the current for tens of kilometres from the source of the trawling, increasing sedimentation rates in deep environments Bottom trawling-induced resuspended sediment mass on the world's continental shelves have been estimated to approximately 22
gigatonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton (United States c ...
s per year, approximately the same as the sediment mass supplied to the continental shelves through the world's rivers. These plumes introduce a
turbidity
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality.
Fluids ...
which decreases light levels at the bottom and can affect
kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms.
Kelp grows in "underwa ...
reproduction.
Bottom trawling can both resuspend and bury biologically recyclable organic material, changing the flow of nutrients and carbon through the food web and thereby alter geomorphological landscapes.
Ocean sediments are the sink for many
persistent organic pollutants
Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. They are toxic chemicals that adversel ...
, usually
lipophilic
Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipo ...
pollutants like
DDT
Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
,
PCB
PCB may refer to:
Science and technology
* Polychlorinated biphenyl, an organic chlorine compound, now recognized as an environmental toxin and classified as a persistent organic pollutant
* Printed circuit board, a board used in electronics
* ...
and
PAH. Bottom trawling mixes these pollutants into the
plankton ecology where they can move back up the
food chain
A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...
and into our food supply.
Phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
is often found in high concentration in soft shallow sediments. Resuspending nutrient solids like these can introduce oxygen demand into the water column, and result in oxygen deficient
dead zones.
Even in areas where the bottom sediments are ancient, bottom trawling, by reintroducing the sediment into the water column, can create
harmful algae blooms. More suspended solids are introduced into the oceans from bottom trawling than any other man-made source.
Multiple large-scale reviews on bottom trawling have noted that there is a great need for further studies that properly examine the effects of nutrient and toxin remobilization as well as
carbon cycling, in order to better estimate
greenhouse gas emissions
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
and hence the impact on
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
.
Deep sea damage
![Results of trawling](https://upload.wikimedia.org/wikipedia/commons/8/86/Results_of_trawling.png)
The
Secretary General of the United Nations
The secretary-general of the United Nations (UNSG or SG) is the chief administrative officer of the United Nations and head of the United Nations Secretariat, one of the six principal organs of the United Nations.
The role of the secretary-ge ...
reported in 2006 that 95 percent of damage to
seamount ecosystems worldwide is caused by
deep sea
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
bottom trawling. A study published in ''
Current Biology
''Current Biology'' is a biweekly peer-reviewed scientific journal that covers all areas of biology, especially molecular biology, cell biology, genetics, neurobiology, ecology, and evolutionary biology. The journal includes research articles, ...
'' suggests a cutoff of is a point which ecological damage increases significantly. Vast amounts of carbon stored in seafloor sediments risk release by bottom-trawling fishing.
Current restrictions
Today, some countries regulate bottom trawling within their jurisdictions:
* The
United States Regional Fishery Management Councils limit bottom trawling in specific closed areas to protect specific species or habitat. For instance, on the
United States West Coast
The West Coast of the United States, also known as the Pacific Coast, Pacific states, and the western seaboard, is the coastline along which the Western United States meets the North Pacific Ocean. The term typically refers to the contiguous U.S. ...
a large Rockfish Conservation Area was created in 2002 prohibiting trawling in most areas of the coast between 75 and 150
fathoms – – to protect
overfished
Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in t ...
rockfish
Rockfish is a common term for several species of fish, referring to their tendency to hide among rocks.
The name rockfish is used for many kinds of fish used for food. This common name belongs to several groups that are not closely related, and ca ...
species. In 2018, these closures were revised to allow trawling in some previously closed areas while closing new areas of sensitive habitat to bottom trawling.
* The
Council of the European Union
The Council of the European Union, often referred to in the treaties and other official documents simply as the Council, and informally known as the Council of Ministers, is the third of the seven Institutions of the European Union (EU) as ...
in 2004 applied "a precautionary approach" and closed the sensitive
Darwin Mounds
Darwin Mounds is a large field of undersea sand mounds situated off the north west coast of Scotland that were first discovered in May 1998. They provide a unique habitat for ancient deep water coral reefs and were found using remote sensing tech ...
off
Scotland
Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
to bottom trawling.
* In 2005, the
United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
's General Fisheries Commission for the Mediterranean (GFCM) banned bottom trawling below 1000 meters (3,281 ft) and, in January 2006, completely closed ecologically sensitive areas off
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
,
Cyprus
Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ge ...
, and
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...
to all bottom trawling.
*
Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...
first recognized in 1999 that trawling had caused significant damage to its cold-water ''
lophelia
''Lophelia pertusa'', the only species in the genus ''Lophelia'', is a cold-water coral that grows in the deep waters throughout the North Atlantic ocean, as well as parts of the Caribbean Sea and Alboran Sea. Although ''L. pertusa'' reefs are h ...
''
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
s. Norway has since established a program to determine the location of cold-water corals within its
exclusive economic zone (EEZ) so as to quickly close those areas to bottom trawling.
*
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
has acted to protect vulnerable
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
C ...
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s from bottom trawling off
Nova Scotia
Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland".
Most of the population are native Eng ...
. The
Northeast Channel was protected by a fisheries closure in 2002, and the
Gully area was protected by its designation as a
Marine Protected Area
Marine protected areas (MPA) are protected areas of seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a conse ...
(MPA) in 2004.
*
Australia in 1999 established the
Tasmanian Seamounts Marine Reserve
Huon Commonwealth Marine Reserve is a 9,991 km2 marine protected area within Australian waters. The former Tasmanian Seamounts Marine Reserve created in 1999 was incorporated into the Huon reserve in 2007, and is part of the South-east Commonwe ...
to prohibit bottom trawling in the south
Tasman Sea
The Tasman Sea ( Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer ...
. Australia also prohibits bottom trawling in the
Great Australian Bight Marine Park
Great Australian Bight Marine Park is the name given to a group of marine protected areas which are located together within both Australian and South Australian jurisdictions in the Great Australian Bight and which has been in use as recently a ...
off
South Australia
South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
near
Ceduna. In 2004, Australia established the world's largest marine protected area in the
Great Barrier Reef Marine Park
The Great Barrier Reef Marine Park protects a large part of Australia's Great Barrier Reef from damaging activities. It is a vast multiple-use Marine Park which supports a wide range of uses, including commercial marine tourism, fishing, ports an ...
, where fishing and other extractive activities are prohibited.
*
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
in 2001 closed 19
seamounts within its EEZ to bottom trawling, including in the
Chatham Rise
The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some from near the South Island in the west, to the Chatham Islands in the east. It is New Zealand's most productiv ...
, sub-Antarctic waters, and off the east and west coasts of the
North Island. New Zealand Fisheries Minister
Jim Anderton
James Patrick Anderton (born Byrne; 21 January 1938 – 7 January 2018) was a New Zealand politician who led a succession of left-wing parties after leaving the Labour Party in 1989.
Anderton's political career began when he was elected to th ...
announced on 14 February 2006 that a draft agreement had been reached with fishing companies to ban bottom trawling in 30 percent of New Zealand's EEZ, an area of about reaching from
subantarctic
The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...
waters to
subtropical ones.
But only a small fraction of the area proposed for protection will cover areas actually vulnerable to bottom trawling.
*
Palau
Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the ...
has banned all bottom trawling within its jurisdiction and by any Palauan or Palauan corporation anywhere in the world.
* The President of
Kiribati
Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),[Kiribati]
''The Wor ...
, Anote Tong, announced in early 2006 the formation of the world's first deep-sea marine reserve area. This measure – the
Phoenix Islands Protected Area
The Phoenix Islands Protected Area (PIPA) is located in the Republic of Kiribati, an ocean nation in the central Pacific approximately midway between Australia and Hawaii. PIPA constitutes 11.34% of Kiribati's exclusive economic zone (EEZ), an ...
– created the world's third-largest marine protected area and may protect deep sea corals, fish, and seamounts from bottom trawling. However, the actual boundaries of this reserve and what harvest limitations may occur therein have not been detailed. Moreover, Kiribati currently has only one
patrol boat
A patrol boat (also referred to as a patrol craft, patrol ship, or patrol vessel) is a relatively small naval vessel generally designed for coastal defence, border security, or law enforcement. There are many designs for patrol boats, and the ...
to monitor this proposed region.
*
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
was the first country to ban industrial trawling in its
territorial waters
The term territorial waters is sometimes used informally to refer to any area of water over which a sovereign state has jurisdiction, including internal waters, the territorial sea, the contiguous zone, the exclusive economic zone, and potent ...
and EEZ in 2009.
*
Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta i ...
passed legislation banning trawling on 18 May 2011 in an effort to restore the territory's devastated fish stocks and marine ecosystem. The ban came into effect on 31 December 2012. The government paid
HK$
The Hong Kong dollar (, sign: HK$; code: HKD) is the official currency of the Hong Kong Special Administrative Region. It is subdivided into 100 cents or 1000 mils. The Hong Kong Monetary Authority is the monetary authority of Hong Kong and ...
1.72 billion to affected trawlers in a buyout scheme. Persons who contravene the ban can be fined or imprisoned under the Fisheries Protection Ordinance (Cap 171).
Lack of regulation
Beyond national jurisdictions, most bottom trawling is unregulated either because there is no
Regional Fisheries Management Organisation A regional fishery body (RFB) is a type of international organization that is dedicated to the sustainability of fishery resources in a particular region, or of highly migratory species. An RFB is classified as one of the following two types:
* reg ...
(RFMO) with competence to regulate, or else what RFMOs that do exist have not actually regulated. The major exception to this is in the Antarctic region, where the
regime has instituted extensive bottom trawling restrictions.
The
North East Atlantic Fisheries Commission
The North East Atlantic Fisheries Commission (NEAFC) is a general regional fishery management organisation that maintains controls over fishing and fishing-related acts in the North Sea, the Irish Sea, the Nordic Seas, the Barents Sea, the White ...
(NEAFC) also recently closed four seamounts and part of the mid-Atlantic Ridge from all fishing, including bottom trawling, for three years. This still leaves most of international waters completely without bottom trawl regulation.
As of May 2007 the area managed under the
South Pacific Regional Fisheries Management Organisation
The South Pacific Regional Fisheries Management Organisation (SPRFMO) is an intergovernmental organization created by international treaty, the ''Convention on the Conservation and Management of High Seas Fishery Resources in the South Pacific Oc ...
(SPRFMO) has gained a new level of protection. All countries fishing in the region (accounting for about 25 percent of the global ocean) agreed to exclude bottom trawling on high seas areas where vulnerable ecosystems are likely or known to occur until a specific impact assessment is undertaken and precautionary measures have been implemented. Observers will also be required on all high seas bottom trawlers to ensure enforcement of the regulations.
Failed United Nations ban
Palau
Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the ...
President
Tommy Remengesau
Thomas Esang "Tommy" Remengesau Jr. (born 28 February 1956) is a Palauan politician; in 2013 he was elected the ninth president of Palau and was re-elected to that office in 2016. Previously he served as the seventh president of the island nat ...
has called for a ban on destructive and unregulated bottom trawling beyond national jurisdictions. Palau has led the effort at the
United Nations
The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
and in the
Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...
to achieve a
consensus by countries to take this action at an international level. Palau has been joined by the
Federated States of Micronesia
The Federated States of Micronesia (; abbreviated FSM) is an island country in Oceania. It consists of four states from west to east, Yap, Chuuk, Pohnpei and Kosraethat are spread across the western Pacific. Together, the states comprise a ...
, the
Republic of the Marshall Islands
The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Intern ...
, and
Tuvalu
Tuvalu ( or ; formerly known as the Ellice Islands) is an island country and microstate in the Polynesian subregion of Oceania in the Pacific Ocean. Its islands are situated about midway between Hawaii and Australia. They lie east-nor ...
in supporting an interim bottom trawling ban at the United Nations. The proposal for this ban did not result in any actual legislation and was blocked.
In 2006,
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
Fisheries Minister
Jim Anderton
James Patrick Anderton (born Byrne; 21 January 1938 – 7 January 2018) was a New Zealand politician who led a succession of left-wing parties after leaving the Labour Party in 1989.
Anderton's political career began when he was elected to th ...
promised to support a global ban on bottom trawling if there was sufficient support to make that a practical option. Bottom trawling has been banned in a third of New Zealand's waters (although a large percentage of these areas were not viable for bottom trawling in the first place)
See also
*
* (DSCC)
*
* , a historic sidewinder trawler
*
References
* National Research Council (US) (2002
''Effects of Trawling and Dredging on Seafloor Habitats.''National Academies Press.
Further reading
*
*
* March, E. J. (1953). Sailing Trawlers: The Story of Deep-Sea Fishing with Long Line and Trawl. Percival Marshal and Company. Reprinted by Charles & David, 1970, Newton Abbot, UK.
External links
Bottom trawling imageryAnnotated satellite images from a number of bottom trawling activities around the world
Deep Sea Conservation CoalitionCampaign for a ban on deep sea bottom trawling
FAO Gear type fact sheetsGear type fact sheet on various types of bottom trawls
Oceana: bottom trawling facts* On the role bottom trawling plays in global fisheries
Bibliography of the Effects of Fishing Gear on the Seabed and Benthic Communities
{{fisheries and fishing
Marine biology
Environmental impact of fishing