Krill fishery
Encyclopedia
The krill fishery is the commercial fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...

 of krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

, small shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

-like marine animals that live in the oceans world-wide. Estimates for how much krill there is vary wildly, depending on the methodology used. They range from 125–725 million tonnes of biomass
Biomass (ecology)
Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms,...

 globally. The total global harvest of krill from all fisheries amounts to 150–200,000 tonnes annually, mainly Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...

 (Euphausia superba) and North Pacific krill (E. pacifica).

Krill are rich in protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 (40% or more of dry weight) and lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

s (about 20% in E. superba). Their exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...

 amounts to some 2% of dry weight of chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...

. They also contain traces of a wide array of hydrolytic enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s such as protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....

s, carbohydrase
Carbohydrase
__Carbohydrase is an enzyme that cleaves carbohydrates into simple sugars.Carbohydrase acts on carbohydrates of which are made from the elements and carbon, hydrogen and oxygen. After reacting these elements are arranged into rings, where 1 ring is a monosaccharide, 2 rings are disaccharides, many...

s, nuclease
Nuclease
A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Older publications may use terms such as "polynucleotidase" or "nucleodepolymerase"....

s and phospholipase
Phospholipase
A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. There are four major classes, termed A, B, C and D, distinguished by the type of reaction which they catalyze:*Phospholipase A...

s, which are concentrated in the digestive gland in the cephalothorax
Cephalothorax
The cephalothorax is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. The word cephalothorax is derived from the Greek words for head and thorax...

 of the krill.

Most krill is used as aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 feed and fish bait
Bait (luring substance)
Bait is any substance used to attract prey, e.g. in a mousetrap.-In Australia:Baiting in Australia refers to specific campaigns to control foxes, wild dogs and dingos by poisoning in areas where they are a problem...

; other uses include livestock or pet foods. Only a small percentage is prepared for human consumption. Their enzymes are interesting for medical applications, an expanding sector since the early 1990s.

Technology

Krill are small animals, considered a type of zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

, and hence need to be fished with very fine-meshed plankton nets. Such nets pose several problems: they tend to clog fast, and they have a very high drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

, producing a bow wave
Bow wave
A bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's wake. A large bow wave slows the ship down, poses a risk to smaller boats, and in a harbor can cause damage to shore facilities and moored ships...

 that deflects the krill to the sides. Trawling
Trawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....

 must hence be done at low speeds. Additionally, fine nets are also very delicate, and the first krill nets designed exploded while fishing through the krill schools. Furthermore, fine nets increase unwanted bycatch, such as fish fingerlings, which might have unforeseen side-effects on the ecosystem, even though large krill aggregations tend to be monospecific.

Yet another problem is bringing the krill catch on board. When the full net is hauled out of the water, the organisms compress each other, resulting in great loss of the krill's liquids. Experiments have been carried out to pump Antarctic krill, while still in water, from the cod end of the net through a large tube on board. This method had already been used by the small fishing boats in Japanese waters; it increases the capture capacity and the processing rate of krill.
One of the first Antarctic krill trawlers to use this technique was the FV Atlantic Navigator, registered in Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...

 and owned by the Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

-based company Aker ASA
Aker ASA
Aker ASA is a Norwegian holding company engaged in offshore fishing, construction and engineering. The company is listed on Oslo Stock Exchange and is controlled by Kjell Inge Røkke with 66.66% ownership through TRG Holding...

, which used this technique in the 2003/04 and 2004/05 fishing seasons. In these seasons, this ship alone caught 25% and 38% of the whole krill catch in CCAMLR
Convention for the Conservation of Antarctic Marine Living Resources
The Convention on the Conservation of Antarctic Marine Living Resources, also Commission on the Conservation of Antarctic Marine Living Resources, and CCAMLR, is part of the Antarctic Treaty System...

 regions. The successor ship of the Atlantic Navigator, the FV Saga Sea, can fish up to about 120,000 tonnes of krill annually, and Aker announced plans to build more such ships.

Krill must be processed within one to three hours after capture due to the rapid enzymatic
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 breakdown and the tainting of the meat by the intestines. They must be peeled because their exoskeleton contains fluoride
Fluoride
Fluoride is the anion F−, the reduced form of fluorine when as an ion and when bonded to another element. Both organofluorine compounds and inorganic fluorine containing compounds are called fluorides. Fluoride, like other halides, is a monovalent ion . Its compounds often have properties that are...

s, which are toxic in high concentrations.

Products

Most krill is processed to produce fish food for use in aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

s and aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

s. The krill is sold freeze-dried, either whole or pulverized. Krill as a food source is known to have positive effects on some fish, such as stimulating appetite or resulting in an increased disease resistance. Furthermore, krill contains carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...

s and is thus used sometimes as a pigmentizing agent to color the skin and meat of some fish. About 34% of the Japanese catch of E. superba and 50% of E. pacifica are used for fish food; the Canadian catch is used almost exclusively for this purpose.

Some 25% of the Japanese catch of E. superba is used in the form of fresh frozen krill as fish bait
Bait (luring substance)
Bait is any substance used to attract prey, e.g. in a mousetrap.-In Australia:Baiting in Australia refers to specific campaigns to control foxes, wild dogs and dingos by poisoning in areas where they are a problem...

; and 50% of the E. pacifica catch is used as chum
Chum
Chum is a fabulous person Chum may refer to:*Chum salmon, a kind of salmon , native to the northern Pacific and adjacent waterways* Chum is a slang term for a friend....

 for sport fishing. About 43% of the Japanese catch of E. superba is processed for human consumption. The Japanese industry produces boiled, frozen krill and peeled tail meat. Other uses include krill pastes or processed krill as food additives, e.g. in the form of krill oil gel capsules.

Medical applications of krill enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s include products for treating necrotic tissue
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 and as chemonucleolytic agents. Of the 376 krill-related patents that had been registered world-wide until 2002, 17% related to medical uses. Most of these medical patents had been registered after 1988.

Antarctic krill

Krill fishery in the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...

 targets the largest species of krill existing, the Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...

 (Euphausia superba), which can grow to about 6 cm (2.4 in). Fishing began in the early 1960s, when the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 launched its first experimental operations. All throughout the decade, preparatory activities were carried out, resulting in small catches of a few tens of tonnes per year. Scientists mapped the locations of krill swarms to determine the best fishing grounds, and engineers developed and improved the equipment necessary to fish and process krill. In 1972, the Soviets set up a permanent fishery in Antarctic waters, landing 7,500 tonnes in 1973 and then expanding quickly. The Japanese began experimental krill fishing operation in the area in 1972 and started full-scale commercial operations in 1975.

Krill catch increased rapidly. In the 1980s, a few additional nations started operating in the area: Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, and South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

. Their catches amounted to a few thousand tonnes annually; the lion's share went to the Soviet Union, followed by Japan. A peak in krill harvest was reached in 1982 with a total production of over 528,000 tonnes, of which the Soviet Union produced 93%. In the following two years, production declined. It is unclear whether this was due to the discovery of fluoride
Fluoride
Fluoride is the anion F−, the reduced form of fluorine when as an ion and when bonded to another element. Both organofluorine compounds and inorganic fluorine containing compounds are called fluorides. Fluoride, like other halides, is a monovalent ion . Its compounds often have properties that are...

s in the krill's exoskeleton or to marketing problems. The trade recovered quickly, though, and reached more than 400,000 tonnes again in 1987.

With the demise of the Soviet Union, two of its successor nations, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 and Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

, took over the operations. Russian operations and catches dwindled, and were abandoned altogether in 1993. Since then, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 is one of the top producers, but facing stiff competition by other countries. Since 2000, the small South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

n Antarctic krill fishery has also expanded considerably. A U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 company entered the market in 2001. The Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 company Aker ASA
Aker ASA
Aker ASA is a Norwegian holding company engaged in offshore fishing, construction and engineering. The company is listed on Oslo Stock Exchange and is controlled by Kjell Inge Røkke with 66.66% ownership through TRG Holding...

 entered the business in 2003 with a ship registered in Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...

.
align=bottom|Annual catch of E. superba by the major fishing nations. Data from the FAO. A dash means "no catch"; a zero indicates a small catch < 500 t.
Country 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09
Japan 36 28 35 43 47 40 60 78 73 79 69 69 78 57 61 63 59 60 67 66 81 67 51 60 34 23 33 24 38 21
South Korea - - 1 2 3 - - 2 2 2 4 1 1 - - - - - 3 0 7 8 14 20 25 27 43 33 38 43
Norway - - - - - - - - - - - - - - - - - - - - - - - - - - 9 40 63 44
Poland 0 - 0 0 - 0 2 3 5 8 3 10 15 7 8 13 22 14 20 20 20 14 16 9 9 4 5 7 8 8
Ukraine - - - - - - - - - - - - 55 - 13 59 10 - - 7 - 14 32 18 12 22 15 - 8 0
USSR/Russia 441 420 492 186 69 228 333 344 310 258 326 249 103 2 - - - - - - - - - - - - - - 0 10
U.S. - - - - - - - - - - - - - - - - - - - - - 2 12 10 9 2 - - - -
Vanuatu - - - - - - - - - - - - - - - - - - - - - - - - 29 48 - - - -
476 448 528 231 119 267 394 426 389 347 402 329 251 65 81 135 91 75 90 91 107 104 125 117 118 129 106 104 156 125


In 1982, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) came into force, as part of the Antarctic Treaty System
Antarctic Treaty System
The Antarctic Treaty and related agreements, collectively called the Antarctic Treaty System or ATS, regulate international relations with respect to Antarctica, Earth's only continent without a native human population. For the purposes of the treaty system, Antarctica is defined as all of the land...

. The CCAMLR was originally signed by fifteen states; as of 2004 it had 24 members. Its purpose is to regulate the fishery in the Southern Ocean to ensure a long-term sustainable development and to prevent overfishing. In 1993, the CCAMLR set forth catch quotas for krill, which amount to nearly five million tonnes per year.

The annual catch of Euphausia superba since the mid-1990s is about 100–120,000 tonnes annually, i.e., about one fiftieth of the CCAMLR catch quota. Still, the CCAMLR is criticized for having defined its catch limits too generously, as there are no precise estimates of the total biomass of Antarctic krill available and there have been reports indicating that it is declining since the 1990s. Plans to take up to 746,000 tonnes a year were disclosed at the 2007 meeting of CCAMLR.

Fishing for Antarctic krill is commonly done from large stern trawlers using midwater trawls. For scientific purposes, vertical trawls using, for example, a bongo net, are also employed.

Around Japan

The krill fishery in Japanese waters primarily targets the North Pacific krill (Euphausia pacifica), which reaches a size of about 2 centimetre (0.78740157480315 in). The annual catch is of the order of 60–70,000 tonnes. Minor fisheries for Euphausia nana (a few thousand tonnes) and Thysannoessa inermis (a few hundred tonnes annually) also exist. The fishing ground are all above the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 close to the coast and at most 200 m (656.2 ft) deep. E. nana reaches only 1.2 cm, and T. inermis can grow to 3 cm (1.2 in).

E. pacifica was fished as early as the 19th century. Fishing is done with small boats. The traditional technique uses bow-mounted trawls, augmented by fish pumps since the 1980s. A bow-mounted trawl can exploit only surface swarms of krill up to a depth of about eight metres. In the 1970s, the krill fishery expanded drastically and began to use also one- or two-boat seines, which can catch swarms as deep as 150 m (492.1 ft). A peak in the krill production was reached in 1992 with over 100,000 tonnes. The following year, catch regulations were enforced, and since then the annual catch has been reduced by about 30%.

Experimental fisheries

Small-scale fisheries for krill also exist in other areas. In Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, fishing for E. pacifica takes place in the Strait of Georgia
Strait of Georgia
The Strait of Georgia or the Georgia Strait is a strait between Vancouver Island and the mainland coast of British Columbia, Canada. It is approximately long and varies in width from...

 off British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

; there is a government-imposed catch limit of 500 tonnes per year. Fisheries targeting the Northern krill
Northern krill
Northern krill, Meganyctiphanes norvegica, is a species of krill that lives in the North Atlantic Ocean. It is an important component of the zooplankton, providing food for whales, fish and birds. M...

 (Meganyctiphanes norvegica), a medium-sized krill reaching body lengths of more than 4 cm (1.6 in), as well as Tysanoessa raschii (2 cm) and T. inermis in the Gulf of St. Lawrence and on the Scotian Shelf have been proposed, but didn't get beyond early experimental stages. They are limited to harvesting a few hundred tonnes of krill per year, and Nicol & Foster consider it unlikely that any new large-scale harvesting operations in these areas will be started due to the opposition from local fishing industries and conservation groups.

External links

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