Krill fishery

Krill fishery

The Krill fishery is the commercial fishery of krill, small shrimp-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 globally.FAO: [ Species Fact Sheet "Euphausia superba"] . Accessed Jun 16, 2005.] The total global harvest of krill from all fisheries amounts to 150 – 200,000 tonnes annually, mainly Antarctic krill ("Euphausia superba") and North Pacific krill ("E. pacifica").

Krill are rich in protein (40% or more of dry weight) and lipids (about 20% in "E. superba"). Their exoskeleton amounts to some 2% of dry weight of chitin. They also contain traces of a wide array of hydrolytic enzymes such as proteases, carbohydrases, nucleases and phospholipases, which are concentrated in the digestive gland in the cephalothorax of the krill.

Most krill is used as aquaculture feed and fish bait; 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.


Krill are small animals, considered a type of zooplankton, 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, producing a bow wave that deflects the krill to the sides. Trawling 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.

width=160px krill trawler FV "Saga Sea"]
One of the first Antarctic krill trawlers to use this technique was the "FV Atlantic Navigator", registered in Vanuatu and owned by the Norwegian-based company Aker ASA," [ Technology of Fishery] ", URL last accessed 2008-07-03.] 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 regions.Rojas, E.: "Antarctic Krill Fishery Observers Should be Mandatory", in " [ The Mail Buoy 9(4)", Winter 2006/2007, Association for Professional Observers. URL last accessed 2008-07-03.] The successor ship of the "Atlantic Navigator", the "FV Saga Sea", can fish up to about 120'000 tonnes of krill annually,fn|a and Aker announced plans to build more such ships.Clover, Ch.: " [ Trawler "poses threat to Antarctic life"] ", The Daily Telegraph (online), September 25, 2006. URL last accessed 2008-07-03.]

Krill must be processed within one to three hours after capture due to the rapid enzymatic breakdown and the tainting of the meat by the intestines. They must be peeled because their exoskeleton contains fluorides, which are toxic in high concentrations.


Most krill is processed to produce fish food for use in aquariums and aquacultures. 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 carotenoids 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; and 50% of the "E. pacifica" catch is used as chum 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 enzymes include products for treating necrotic tissue 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.Nicol, S.; Foster, J.: " [ Recent trends in the fishery for Antarctic krill] ", Aquat. Living Resour. 16, pp. 42 – 45; 2003.]

Antarctic krill fishery

Krill fishery in the Southern Ocean targets the largest species of krill existing, the Antarctic krill ("Euphausia superba"), which can grow to about 6 cm. Fishing began in the early 1960s, when the Soviet Union 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, Chile, and South Korea. 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 fluorides 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 and Ukraine, took over the operations. Russian operations and catches dwindled, and were abandoned altogether in 1993. Since then, Japan is one of the top producers, but facing stiff competition by other countries. Since 2000, the small South Korean Antarctic krill fishery has also expanded considerably. A U.S. company entered the market in 2001. The Norwegian company Aker ASA entered the business in 2003 with a ship registered in Vanuatu.

In 1982, the CCAMLR (Convention on the Conservation of Antarctic Marine Living Resources) came into force, as part of the Antarctic Treaty System. 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.CCAMLR: [ "Harvested species: Krill "(Euphausia superba)] . Accessed June 20, 2005.]

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.Siegel, V.; Loeb, V.: "Recruitment of Antarctic krill "Euphausia superba" and possible causes for its variability", Mar. Ecol. Prog. Ser. 123, pp. 45 – 56; 1995.] Plans to take up to 746,000 tonnes a year were disclosed at the 2007 meeting of CCAMLR. [Darby, A.: " [ Ecologists fear huge rise in krill catch] ", Sydney Morning Herald, November 5, 2007. URL last accessed 2008-03-27.] Antarctic and Southern Ocean Coalition: " [ Krill Industry Report 1] ", June 20, 2007. URL last accessed 2008-07-03.]

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.

Krill fisheries around Japan

The krill fishery in Japanese waters primarily targets the North Pacific krill ("Euphausia pacifica"), which reaches a size of about 2 cm. 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 close to the coast and at most 200 m deep. "E. nana" reaches only 1.2 cm, and "T. inermis" can grow to 3 cm.

"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. 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, fishing for "E. pacifica" takes place in the Strait of Georgia off British Columbia; there is a government-imposed catch limit of 500 tonnes per year. Fisheries targeting the Northern krill ("Meganyctiphanes norvegica"), a medium-sized krill reaching body lengths of more than 4 cm, 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.


fnb|a This claim does not match the FAO and CCAMLR data at all; the "Saga Sea" would have caught "all" of the krill reported to have been caught by these agencies. Aker themselves give much more modest figures (which "do" match the FAO/CCAMLR data) in their 2007 quartely reports.Aker BioMarine: "Quarterly reports [ 1/2007] and [ 3/2007] ". URLs last accessed 2008-07-03.] For the 2007/08 season, the "Saga Sea" has a catch limit of 80'000 tonnes." [ Vessel license for the "Saga Sea", season 2007/08] ", Norwegian Directorate of Fisheries, Bergen, Norway; November 20, 2007. URL last accessed 2008-07-03.]


Further reading

*Everson, I. (ed.): "Krill: biology, ecology and fisheries." Oxford, Blackwell Science; 2000. ISBN 0-632-05565-0.
*Nicol, S.; Endo, Y.: " [ Krill fisheries: Development, management and ecosystem implications] ", Aquat. Living Resour. 12, pp. 105 – 120, 1999.

External links

*The main reference for this article is an FAO report from 1997: Nicol, S.; Endo, Y.: " [ Krill Fisheries of the World] ", FAO Fisheries Technical Paper 367; 1997.

* An active network of international non-governmental organizations dedicated to the protection of Antarctic krill is the [ Antarctic Krill Conservation Project] , started by the [ Antarctic and Southern Ocean Coalition] and other entitites.

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