The krill fishery is the fishing industry that harvests krill, small shrimp-like marine animals found in oceans around the world. The current estimate for the total weight of Antarctic krill (Euphausia superba) is 379 million tonnes. The total amount of krill caught worldwide each year is between 150,000 and 200,000 tonnes. Most of this comes from Antarctic krill and North Pacific krill (E. pacifica).

Krill are rich in protein (40% or more of their dry weight) and lipids (about 20% in E. superba). Their outer shell makes up about 2% of their dry weight and is made of a substance called chitin. Krill also contain small amounts of various enzymes, such as proteases, carbohydrases, nucleases, and phospholipases. These enzymes are concentrated in a part of the krill’s body called the cephalothorax.

Most krill is used as food for farmed fish and as bait for fishing. Other uses include food for livestock or pets. Only a small amount is prepared for people to eat. The enzymes found in krill are of interest for medical uses, which has become a growing area since the early 1990s.

Technology

Krill are tiny animals, classified as zooplankton, and must be caught using nets with very small holes. These nets face challenges: they clog quickly, create high resistance in water, and produce waves that push krill away from the net. Because of this, fishing must be done slowly. Also, these nets are fragile, and early krill nets sometimes broke during fishing. Fine nets also catch unwanted animals, like young fish, which could harm the ecosystem, even though krill groups are often made up of only one species.

Another challenge is handling krill after catching. When nets are pulled from the water, krill press together, causing them to lose body fluids. Scientists tested a method to pump krill still in water from the net’s end through a large tube on the boat. This technique, already used by small boats in Japan, improves how much krill can be caught and processed.

The first Antarctic krill trawler to use this method was the FV Atlantic Navigator, registered in Vanuatu and owned by a Norwegian company, Aker ASA. During the 2003/04 and 2004/05 seasons, this ship caught 25% and 38% of all krill in CCAMLR regions. Its successor, the FV Saga Sea, can catch about 120,000 tonnes of krill yearly. Aker planned to build more ships, like the Antarctic Endurance, which launched in early 2019.

Krill must be processed within one to three hours after being caught because their bodies break down quickly, and their intestines can make the meat taste bad. They must also be peeled because their shells contain fluorides, which are harmful in large amounts.

Products

Krill is a good source of protein and omega-3 fatty acids. These nutrients are being developed for use as human food, dietary supplements in oil capsules, food for livestock and pets, and fish food. Most krill is processed into fish food for aquariums and fish farming. Krill is sold freeze-dried, either whole or crushed. Krill has benefits for some fish, such as improving appetite or increasing disease resistance. Krill also contains carotenoids, which are sometimes used to color the skin and meat of certain fish. About 34% of Japan’s catch of E. superba and 50% of E. pacifica are used for fish food. In Canada, nearly all krill caught is used for this purpose.

One quarter of Japan’s E. superba catch is used as fresh frozen krill for fish bait, and half of E. pacifica is used as chum for sport fishing. Japan produces boiled, frozen krill and peeled tail meat. Other uses include krill pastes or processed krill as food additives, such as krill oil gel capsules. Only a small amount of E. superba is used for human consumption.

Krill enzymes are used in medical products to treat dead tissue and as chemonucleolytic agents. Of the 376 krill-related patents registered worldwide by 2002, 17% were related to medical uses. Most of these patents were registered after 1988.

Antarctic krill

The krill fishery in the Southern Ocean focuses on the largest krill species, the Antarctic krill (Euphausia superba), which can grow up to about 6 cm (2.4 in). Krill are found in oceans worldwide, but fishing in the Southern Ocean is preferred because krill are more easily caught and more abundant there. In particular, Antarctic seas are considered untouched, and krill from these areas are often described as a "clean product." Krill fishing began in the early 1960s when the Soviet Union started experimental operations. During the 1960s, preparations were made, leading to small catches of a few tens of tonnes per year. Scientists mapped krill swarms to identify the best fishing areas, and engineers developed tools to catch and process krill. In 1972, the Soviet Union established a permanent fishery in Antarctic waters, landing 7,500 tonnes in 1973 and expanding quickly afterward. Japan began experimental krill fishing in the same year and started full-scale commercial operations in 1975.

Krill catches increased rapidly. In the 1980s, several other countries, including Poland, Chile, and South Korea, began operating in the region. Their annual catches totaled a few thousand tonnes, while the Soviet Union and Japan captured the majority of the krill. The highest krill harvest was recorded in 1982, with over 528,000 tonnes caught, 93% of which came from the Soviet Union. Production dropped in the following two years, though the cause is unclear—it may have been due to the discovery of fluorides in krill exoskeletons or marketing challenges. The trade recovered quickly, reaching over 400,000 tonnes by 1987.

After the Soviet Union collapsed, its successor states, Russia and Ukraine, took over krill operations. Russian fishing and catches declined and stopped completely in 1993. Since then, Japan has remained one of the top krill producers but faces competition from other nations. Since 2000, South Korea’s Antarctic krill fishery has grown significantly. A U.S. company entered the market in 2001, and the Norwegian company Aker ASA began operations in 2003 using a ship registered in Vanuatu.

In 1982, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) was established as part of the Antarctic Treaty System. Initially signed by 15 countries, CCAMLR had 24 members by 2004. Its goal is to manage krill fishing in the Southern Ocean to ensure long-term sustainability and prevent overfishing. In 1993, CCAMLR set annual krill catch limits of nearly 5 million tonnes.

Since the mid-1990s, annual catches of Euphausia superba have averaged about 100,000 to 120,000 tonnes, or about one-fiftieth of the CCAMLR quota. Despite this, CCAMLR has faced criticism for setting limits too high, as there are no precise estimates of total krill biomass, and some reports suggest krill populations have declined since the 1990s. At a 2007 CCAMLR meeting, plans were discussed to allow up to 746,000 tonnes of krill to be caught annually.

Before specialized krill trawlers like Antarctic Endurance were developed, krill fishing was done using large stern trawlers with midwater trawls. For scientific research, vertical trawls, such as those using bongo nets, are also used.

In 2018, it was announced that nearly all krill fishing companies operating in Antarctica would stop fishing in large areas near the Antarctic Peninsula by 2020, including "buffer zones" around penguin breeding colonies.

Around Japan

The krill fishery in Japanese waters mainly catches the North Pacific krill (Euphausia pacifica), which grows to about 2 centimeters (0.79 inches). Each year, about 60,000 to 70,000 tonnes of this species are caught. Smaller fisheries also exist for Euphausia nana (a few thousand tonnes annually) and Thysannoessa inermis (a few hundred tonnes annually). These fishing areas are near the coast, above the continental shelf, and no deeper than 200 meters (660 feet). E. nana grows to about 1.2 centimeters, and T. inermis can reach up to 3 centimeters (1.2 inches).

E. pacifica has been fished since the 19th century. Small boats are used, and the traditional method involves bow-mounted trawls, which are helped by fish pumps since the 1980s. These trawls can only catch krill near the surface, up to about 8 meters deep. In the 1970s, the fishery expanded and began using one- or two-boat seines, which can catch krill swarms as deep as 150 meters (490 feet). In 1992, the fishery reached its highest production with over 100,000 tonnes. The next year, catch limits were introduced, and since then, the annual catch has decreased by about 30%.

Experimental fisheries

Small-scale fisheries for krill also occur in other regions. In Canada, fishing for E. pacifica happens in the Strait of Georgia near British Columbia, where the government has set a yearly catch limit of 500 tonnes. Proposed fisheries for Northern krill (Meganyctiphanes norvegica), a medium-sized krill that can grow longer 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, were considered but did not move past early testing stages. These fisheries would collect only a few hundred tonnes of krill each year. Experts think it is unlikely that large-scale harvesting in these areas will begin because of opposition from local fishing industries and conservation groups.