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A fishery is an area with an associated fish or aquatic population which is harvested for its commercial value. Fisheries can be wild or farmed. Most of the world's wild fisheries are in the ocean. This article is an overview of ocean fisheries.
Oceans occupy 71 percent of the Earth's surface. They are divided into five major oceans, which in decreasing order of size are: the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean. Over 70 percent of the world catch from the sea comes from the Pacific Ocean.
The Pacific Ocean is the largest of the world's oceans, extending from the Arctic in the north to Antarctica in the south. Covering 169.2 million square kilometers, it is larger than all of the Earth's land area combined. The Pacific contains 25,000 islands (over half the islands in the world), most of which are south of the equator.
The Pacific's greatest asset is its fish. The shoreline waters of the continents and the more temperate islands yield herring, salmon, sardines, snapper, swordfish, and tuna, as well as shellfish.
The Celebes Sea has warm clear waters and harbors about 580 of the world's 793 species of reef-building corals, which grow as some of the most bio-diverse coral reefs in the world, and an impressive array of marine life, including whales and dolphins, sea turtles, manta rays, eagle rays, barracuda, marlin and other reef and pelagic species. Tuna and yellow fin tuna are also abundant. The sea also yields other aquatic products like sea tang.
The Coral Sea is an ecologically important source of coral.
The East China Sea.
The Philippine Sea.
The Sea of Japan. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure. It has an area of 978,000 square kilometre, a mean depth of 1,753 meters, and a maximum depth of 3,742 meters.
The South China Sea is the repository of large sediment volumes delivered by the Mekong River, Red River and Pearl River. Within the sea, there are over 200 identified islands and reefs, including a 100 km wide seamount with a depth of 20 m and an area of 8,866 km². According to studies made by the Department of Environment and Natural Resources, Philippines, this body of water holds one third of the all world's marine biodiversity, thereby making it a very important area for the ecosystem.
The Sulu Sea.
The Tasman Sea features a number of coastal islands and mid-sea island groups.
The Yellow Sea
The Atlantic Ocean is the second-largest ocean covering 106.4 million square kilometres with a coastline of 111,000 kilometres. It occupies about one-fifth of the Earth's surface.
The ocean has some of the world's richest fishing resources, especially in the waters covering the shelves. The major species of fish caught are Cape Cod, the Bahama Banks, the waters around Iceland, the Irish Sea, the Dogger Bank of the North Sea, and the Falkland Banks. Eel, lobster, and whales have also been taken in great quantities. Because of the threats to the ocean environment presented by oil spills, marine debris, and the incineration of toxic wastes at sea, various international treaties exist to reduce some forms of pollution.
The Baltic Sea. Approximately 100,000 km² of the Baltic's seafloor (a quarter of its total area) is a variable dead zone. The more saline (and therefore denser) water remains on the bottom, isolating it from surface waters and the atmosphere. This leads to decreased oxygen concentrations within the zone. It is mainly bacteria that grow in it, digesting organic material and releasing hydrogen sulfide. Because of this large anaerobic zone, the seafloor ecology differs from that of the neighbouring Atlantic.
The Black Sea.
The Caribbean Sea is home to about 29% of the world's coral reefs. Currently, unusually warm Caribbean waters are endangering the Caribbean coral reefs. Coral Reefs support some of the most diverse habitats in the world, but are fragile ecosystems. When tropical waters exceed 85 degrees Fahrenheit for an extended period of time, microscopic plants called zooxanthellae die off. These plant provide food for the coral and give them their color. The resultant bleaching of the coral reefs kills them, and ruins the ecosystem. Up to 42% of the coral colonies have gone completely white, while 95% have undergone at least some bleaching. The habitats supported by the reefs are critical to such tourist activities such as fishing and diving, and provide an annual economic value to Caribbean nations of $3.1-$4.6 billion. Continued destruction of the reefs could severely damage the region's economy. A Protocol of the Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region came in effect in 1986 to protect the various endangered marine life of the Caribbean through forbidding human activities that would advance the continued destruction of such marine life in various areas. Currently this protocol has been ratified by 15 countries.
The Gulf of Mexico. The outer margins of the wide continental shelves of Yucatán and Florida receive cooler, nutrient-enriched waters from the deep by a process known as upwelling, which stimulates plankton growth in the euphotic zone. This attracts fish, shrimp, and squid. River drainage and atmospheric fallout from industrial coastal cities also provide nutrients to the coastal zone.
The Labrador Sea
The Mediterranean Sea. Being nearly landlocked affects the Mediterranean Sea's properties; for instance, tides are very limited as a result of the narrow connection with the Atlantic Ocean. Evaporation greatly exceeds precipitation and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin. Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward. This pressure gradient pushes relatively cool, low-salinity water from the Atlantic across the basin; it warms and becomes saltier as it travels east, then sinks in the region of the Levant and circulates westward, to spill over the Strait of Gibraltar. Thus, seawater flow is eastward in the Strait's surface waters, and westward below; once in the Atlantic, this chemically-distinct "Mediterranean Intermediate Water" can persist thousands of kilometers away from its source.
Many marine species have been almost wiped out because of the sea's pollution. The Mediterranean Monk Seal is considered to be among the world's most endangered marine mammals.
The Mediterranean is also plagued by marine debris. A 1994 study of the seabed using trawl nets around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per square kilometre. Plastic debris accounted for 76%, of which 94% was plastic bags.
The North Sea. A large part of the European drainage basin empties into the North Sea including water from the Baltic Sea. Fishing in the North Sea is concentrated in the southern part of the coastal waters. The main method of fishing is trawling. Annual catches grew each year until the 1980s, when a high point of more than 3 million metric tons (3.3 million S/T) was reached. Since then, the numbers have fallen back to around 2.3 million tons (2.5 million S/T) annually with considerable differences between years. Besides the fish caught, it is estimated that 150,000 metric tons (165,000 S/T) of unmarketable by-catch are caught and around 85,000 metric tons (94,000 S/T) of dead and injured invertebrates.
The Norwegian Sea. In the Norwegian Sea and Greenland Sea, surface water descends two to three kilometres down to the bottom of the ocean, forming cold, oxygen-rich groundwater. As a result, there is a warm surface current and a cold depth current running along the west coast of Norway. The so-called East Iceland Current transports cold water south from the Norwegian Sea towards Iceland and then east, along the Arctic Circle. In the Norwegian Current, a branch of the Gulf Stream carries warm water masses northward and contributes to the mild and moist climate in Norway. The Norwegian Sea is the source of much of the North Atlantic Deep Water. The region remains ice-free due to the warm and saline Norwegian Atlantic Current. It provides rich fishing grounds, with catches mostly consisting of cod, herrings, sardines and anchovies. Nowadays, shifts and fluctuations in these currents are closely monitored, as they are thought to be indicators for an ongoing climate change.
The Scotia Sea. Habitually stormy and cold, about half of the sea falls above the continental shelf.
The ocean's continental shelves are narrow, averaging 200 kilometres (120 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000 kilometres (620 mi). The average depth of the ocean is 3,890 metres (12,760 feet). The remaining 14% is layered with terrigenous sediments. Glacial outwash dominates the extreme southern latitudes.
The Andaman Sea is a body of water to the southeast of the Bay of Bengal, south of Myanmar, west of Thailand and east of the Andaman Islands; it is part of the Indian Ocean. It is roughly 1,200 kilometres (750 mi) long (north-south) and 650 kilometres (400 mi) wide (east-west), with an area of 797,700 square kilometres (308,000 sq mi). Its average depth is 870 meters (2,854 ft), and the maximum depth is 3,777 meters (12,392 ft).
The Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui, the north-east point of Somalia, Socotra and Kanyakumari (Cape Comorin) in India.
The maximum width of the Arabian Sea is approximately 2,400 km (1,490 mi), and its maximum depth is 4,652 metres (15,262 ft),
The Bay of Bengal occupies an area of 2,172,000 km². A number of large rivers – Ganges, Brahmaputra, Ayeyarwady, Godavari, Mahanadi, Krishna and Kaveri – flow into the Bay of Bengal. The islands in the bay are very numerous, including the Andaman, Nicobar and Mergui groups.
The Bay of Bengal is full of biological diversity, diverging amongst coral reefs, estuaries, fish spawning and nursery areas, and mangroves. The Bay of Bengal is one of the World's 64 largest marine ecosystems.
Kerilia jerdonii is a sea snake of the Bay of Bengal. Glory of Bengal Cone (Conus bengalensis) is just one of the seashells which can be photographed along beaches of the Bay of Bengal.
An endangered species, the Olive Ridley sea turtle can survive because of the nesting grounds made available at the Gahirmatha Marine Wildlife Sanctuary, Gahirmatha Beach, Orissa, India.
Bryde's Whale which can be seen in the Bay of Bengal is the 10th heaviest animal of the world, weighing in at 22,000 kg (48,000 lb).
Marlin, barracuda, skipjack tuna, (Katsuwonus pelamis), yellowfin tuna, Indo-Pacific humpbacked dolphin (Sousa chinensis), and Bryde's whale (Balaenoptera edeni) are a few of the marine animals. Bay of Bengal Hogfish (Bodianus neilli) is a type of Wrass which live in turbid lagoon reefs or shallow coastal reefs. Schools of dolphins can be seen, whether they are the bottle nose dolphin (Tursiops truncatus), Pantropical spotted dolphin (Stenella attenuata) or the spinner dolphin (stenella longirostris) . Tuna and dolphins are usually residing in the same waters. In shallower and warmer coastal waters the Irrawaddy Dolphins (Orcaella brevirostris) can be found.
The Great Australian Bight is a large bight, or open bay located off the central and western portions of the southern coastline of mainland Australia.
The coast line of the Great Australian Bight is characterised by stunning cliff faces (up to 60 m high), surfing beaches and rock platforms, ideal for whale-watching. The waters of the Great Australian Bight, despite being relatively shallow, are not fertile. While most continental shelves are rich in sea life and make popular fishing areas, the barren deserts north of the bight have very little rainfall, and what there is mostly flows inland, to dissipate underground or in salt lakes. In consequence, the Great Australian Bight receives very little of the runoff that fertilises most continental shelves and is essentially a marine desert. It is probably best noted for the large number of sharks that frequent its coastal waters, as well as the increasing numbers of Southern Right Whales that migrate within the region.
Economically, the Bight has been exploited over many years as part of the fishing, whaling and shellfish industries. Bluefin tuna have been a favoured target of fishing in the Bight.
The Gulf of Oman is a gulf that connects the Arabian Sea with the Strait of Hormuz which then runs to the Persian Gulf.
The Mozambique Channel is a portion of the Indian Ocean between the island of Madagascar and southeast Africa, namely Mozambique. The channel is approximately 460 kilometers across at its narrowest point between Angoche, Mozambique, and Tambohorano, Madagascar. It reaches a depth of 3,292 meters about 230 kilometers off the coast of Mozambique. A warm current flows in a southward direction in the channel, leading into the Agulhas Current off the east coast of South Africa. It is 1600 kilometers long and its width varies from 400 to 950 kilometers.
The Persian Gulf is an extension of the Indian Ocean located between Iran and the Arabian Peninsula. The natural environment of the Persian Gulf is very rich with good fishing grounds, extensive coral reefs, and abundant pearl oysters, but its ecology has become increasingly under pressure from the heavy industrialisation and in particular the repeated major petroleum spillages associated with recent wars fought in the region.
The Red Sea occupies a part of the Great Rift Valley, and has a surface area of 438,000 km². It is 2250 km long and, at its widest point, 355 km wide. It has a maximum depth of 2211 m in the central median trench and an average depth of 490 m (1,608 feet ), but there are also extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species and 200 soft and hard corals and is the world's most northern tropical sea.
The Red Sea is a rich and diverse ecosystem. More than 1100 species of fish have been recorded in the Red Sea, and around 10% of these are found nowhere else. This also includes around 75 species of deepwater fish. The rich diversity is in part due to the 2,000 km (1,240 mi) of coral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders (such as the blue hole at Dahab). These coastal reefs are also visited by pelagic species of red sea fish, including some of the 44 species of shark.
Approximately 40% of the Red Sea is quite shallow (under 100 m/330 ft), and about 25% is under 50 m (164 ft) deep. About 15% of the Red Sea is over 1,000 m (3,300 ft) depth that forms the deep axial trough. Shelf breaks are marked by coral reefs Continental slope has an irregular profile (series of steps down to ~500 m/1,640 ft)
The Southern Ocean is the fourth-largest ocean, covering 20,327,000 square kilometers. It is typically between 4,000 and 5,000 meters deep with only limited areas of shallow water. The Antarctic continental shelf is narrow and unusually deep, its edge lying at up to 800 meters, compared to a global mean of 133 meters.
The Antarctic Circumpolar Current moves perpetually eastward — chasing and joining itself, and at 21,000 kilometers is the world's longest ocean current, transporting 130 million cubic meters per second — 100 times the flow of all the world's rivers. The Antarctic ice pack fluctuates from an average minimum of 2.6 million square kilometers in March to about 18.8 million square kilometers in September.
Fauna: squid, whales, seals, krill, various fish
Increased solar ultraviolet radiation resulting from the Antarctic ozone hole has reduced marine primary productivity (phytoplankton) by as much as 15% and has started damaging the DNA of some fish. Illegal, unreported, and unregulated fishing, especially the landing of an estimated five to six times more Patagonian toothfish than the regulated fishery, likely affects the sustainability of the stock. Long-line fishing for toothfish causes a high incidence of seabird mortality.
The International Whaling Commission prohibits commercial whaling south of 40 degrees south (south of 60 degrees south between 50 degrees and 130 degrees west). Japan does not recognize this and they carry out an annual whale-hunt which they say is for scientific research. See Southern Ocean Whale Sanctuary. The Convention for the Conservation of Antarctic Seals has limited seal-hunting. The Convention on the Conservation of Antarctic Marine Living Resources regulates fishing in the region.
The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It is mostly ice-covered, averaging about 3 km (1.9 mi) in thickness and roughly the size of Texas.
The Bellingshausen Sea is an area along the west side of the Antarctic Peninsula between Alexander Island and Thurston Island.
The Ross Sea is a deep bay of the Southern Ocean in Antarctica between Victoria Land and Marie Byrd Land. The southern part is covered by the Ross Ice Shelf. In the west of the Ross sea, McMurdo Sound is a port which is usually free of ice during the summer.
A 10 metre (32.8 feet) long colossal squid weighing 495 kilograms (1,091 lb) was captured in the Ross Sea on 22 February 2007.
There are two main species of toothfish: the Patagonian toothfish, Dissostichus eleginoides, which occurs mainly in Subantarctic waters, and the , D. mawsoni, which is found only in Antarctic waters. The Antarctic toothfish is caught from the Polar Convergence (at about 60° S) south to the Antarctic continent, whereas the Patagonian toothfish is mainly caught north of 65° S. The Ross Sea region is unusual because between these latitudes both species are abundant and show considerable overlap in their distribution. Indeed, over 90% of the longlines set in the fishery in this area have both species on the same line. Both species are found down to depths of over 2000 m
The Ross Sea toothfish fishery is the southernmost fishery in the world. The extreme cold and ice conditions can make fishing both difficult and dangerous. During most of the year the Ross Sea itself is covered by ice. However, during January and February, areas of open water (called polynas) allow access to the continental shelf and slope. Longline vessels (predominantly from New Zealand, but also from South Africa, Russia, and Uruguay) have taken advantage of this to develop an exploratory fishery. They start working in the deep south, and as the season progresses they move north to stay ahead of the freezing sea ice, and by May are restricted to the northernmost fishing grounds. CCAMLR agrees on annual precautionary catch limits. Since 1998, the catch has steadily increased from about 40 t to over 1350 t in 2002 (all of these catches are well within the CCAMLR limits). Because it is a high latitude fishery, Antarctic toothfish has formed over 95% of the catch. Up to three New Zealand vessels have been involved in the fishery in any year. However, in the 2003 season up to six New Zealand vessels are fishing in these waters.
The Weddell Sea land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. Much of the southern part of the sea, up to Elephant Island, is permanent ice, the Filchner-Ronne Ice Shelf. At its widest the sea is around 2,000 km across, in area it is around 2.8 million km². The ice shelves which used to extend roughly 3,900 square miles (10,000 km2) over the Weddell Sea have completely disappeared by 2002.
The Arctic Ocean is the smallest of the world's five major oceans and the shallowest. Almost completely surrounded by Eurasia and North America, it is largely covered by sea ice throughout the year. Its temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major seas, due to low evaporation, heavy freshwater inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. In summer the icepack shrinks about fifty percent.
Endangered marine species include walruses and whales. The area has a fragile ecosystem which is slow to change and slow to recover from disruptions or damage. The Arctic Ocean has relatively little plant life except for phytoplankton. Phytoplankton are a crucial part of the ocean and there are massive amounts of them in the Arctic. Nutrients from rivers and the currents of the Atlantic and Pacific oceans provide food for the Arctic phytoplankton.
Fisheries science, Marine conservation, Marine biology, Greenpeace, Marine pollution
Energy, Water, Fisheries Law, Marine conservation, Mining
Fishing, Fisheries science, Sustainability, Diversity of fish, Marine conservation