SafekipediaA tuna (pl.: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. This family includes 15 different species spread across five genera. These fish come in many sizes, from the small bullet tuna, which can grow up to about 50 cm (1.6 ft) long, to the massive Atlantic bluefin tuna, which can reach nearly 4.6 meters (15 ft) and weigh over 684 kilograms (1,508 lb).
Unlike most fish, tuna, along with opah and mackerel sharks, can keep their body temperature higher than the water around them. This special ability helps them stay active and strong. Tuna have sleek, streamlined bodies that make them excellent swimmers. Some, like the yellowfin tuna, can race through the water at speeds of up to 75 kilometers per hour (47 miles per hour).
Tuna live in warm seas all around the world and are highly valued for food. They are also popular among people who enjoy fishing in open waters, called bluewater. However, because many people catch tuna for food, some species, such as the southern bluefin tuna, are now in danger of disappearing forever due to overfishing.
Etymology
The word "tuna" comes from the Spanish word atún. There are many kinds of tuna, but the "true" tunas belong to the group called Thunnus. For a long time, people thought there were seven kinds of these true tunas, and that the Atlantic bluefin tuna and the Pacific bluefin tuna were almost the same kind of fish. But in 1999, a scientist named Collette studied them closely and found that they are actually two different species.
The true tunas are divided into two smaller groups: one group includes the bluefin tunas, and the other group includes the yellowfin tunas. Altogether, there are many different species of tuna in the larger tuna family.
| Thunnus, the true tunas | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Image | Common name | Scientific name | Maximum length | Common length | Maximum weight | Maximum age | Trophic level | IUCN status | |
| Thunnus (Thunnus) – the bluefin group | |||||||||
| Albacore tuna | T. alalunga (Bonnaterre, 1788) | 1.4 m (4.6 ft) | 1.0 m (3.3 ft) | 60.3 kg (133 lb) | 9–13 yrs | 4.31 |  Least Concern | ||
| Southern bluefin tuna | T. maccoyii (Castelnau, 1872) | 2.45 m (8.0 ft) | 1.6 m (5.2 ft) | 260 kg (570 lb) | 20–40 yrs | 3.93 |  Endangered | ||
| Bigeye tuna | T. obesus (Lowe, 1839) | 2.5 m (8.2 ft) | 1.8 m (5.9 ft) | 210 kg (460 lb) | 5–16 yrs | 4.49 |  Vulnerable | ||
| Pacific bluefin tuna | T. orientalis (Temminck & Schlegel, 1844) | 3.0 m (9.8 ft) | 2.0 m (6.6 ft) | 450 kg (990 lb) | 15–26 yrs | 4.21 |  Near Threatened | ||
| Atlantic bluefin tuna | T. thynnus (Linnaeus, 1758) | 4.6 m (15 ft) | 2.0 m (6.6 ft) | 684 kg (1,508 lb) | 35–50 yrs | 4.43 | Least Concern | ||
| Thunnus (Neothunnus) – the yellowfin group | |||||||||
| Blackfin tuna | T. atlanticus (Lesson, 1831) | 1.1 m (3.6 ft) | 0.7 m (2.3 ft) | 22.4 kg (49 lb) | 4.13 | Least concern | |||
| Longtail tuna, northern bluefin tuna, tongol tuna | T. tonggol (Bleeker, 1851) | 1.45 m (4.8 ft) | 0.7 m (2.3 ft) | 35.9 kg (79 lb) | 18 years | 4.50 |  Data deficient | ||
| Yellowfin tuna | T. albacares (Bonnaterre, 1788) | 2.4 m (7.9 ft) | 1.5 m (4.9 ft) | 200 kg (440 lb) | 5–9 yrs | 4.34 | Least Concern | ||
| Other tuna species | ||||||||
|---|---|---|---|---|---|---|---|---|
| Common name | Scientific name | Maximum length | Common length | Maximum weight | Maximum age | Trophic level | IUCN status | |
| Slender tuna | Allothunnus fallai (Serventy, 1948) | 1.05 m (3.4 ft) | 0.86 m (2.8 ft) | 13.7 kg (30 lb) | 3.74 | Least concern | ||
| Bullet tuna | Auxis rochei (Risso, 1810) | 0.5 m (1.6 ft) | 0.35 m (1.1 ft) | 1.8 kg (4.0 lb) | 5 years | 4.13 | Least concern | |
| Frigate tuna | Auxis thazard (Lacépède, 1800) | 0.65 m (2.1 ft) | 0.35 m (1.1 ft) | 1.7 kg (3.7 lb) | 5 years | 4.34 | Least concern | |
| Mackerel tuna, Kawakawa | Euthynnus affinis (Cantor, 1849) | 1.0 m (3.3 ft) | 0.6 m (2.0 ft) | 13.6 kg (30 lb) | 6 years | 4.50 | Least concern | |
| Little tunny | Euthynnus alletteratus (Rafinesque, 1810) | 1.2 m (3.9 ft) | 0.8 m (2.6 ft) | 16.5 kg (36 lb) | 10 years | 4.13 | Least concern | |
| Black skipjack tuna | Euthynnus lineatus (Kishinouye, 1920) | 0.84 m (2.8 ft) | 0.6 m (2.0 ft) | 11.8 kg (26 lb) | 3.83 | Least concern | ||
| Skipjack tuna | Katsuwonus pelamis (Linnaeus, 1758) | 1.1 m (3.6 ft) | 0.8 m (2.6 ft) | 34.5 kg (76 lb) | 6–12 yrs | 3.75 | Least concern | |
Biology
See also: Thunnus
Tuna are sleek, fast fish with two special dorsal fins that can lay flat against their backs. They have a curved, moon-shaped tail and shiny, silvery bellies that help them blend into deeper water.
Tuna can keep some parts of their bodies warmer than the surrounding water, which helps them swim faster and farther than many other fish. They do this by recycling heat from their blood. Their red muscle tissue, rich in oxygen, also supports powerful swimming. While this helps them move quickly, tuna sometimes face limits due to tiny bubbles that form around their fins when they swim too fast.
Fishing
Tuna is a very important fish for commercial fishing around the world. Some of the main types caught are yellowfin, bigeye, bluefin, albacore, and skipjack. Tuna fishing has grown a lot over the years, with more than four million tons caught each year. Most of this comes from the Pacific Ocean, followed by the Indian Ocean and then the Atlantic Ocean.
There are many ways to catch tuna, including using hooks and lines, purse-seine nets, and longlines. Tuna is also caught for sport and can be very strong when hooked. Some old methods, like the Almadraba, still used today, involve nets to trap tuna. There is also fish farming, where tuna are raised in nets in the water. Japan is a leader in studying and farming tuna.
| Record bluefin tuna auctions at Tokyo's Tsukiji fish market and Toyosu Market | ||||||
|---|---|---|---|---|---|---|
| (Highlighted field indicates new record price for a single fish) | ||||||
| Year | Total weight | Total sale | Unit price | Source | ||
| (JP ¥) | (US $) | (¥ / kg) | ($ / lb) | |||
| 2001 | 202 kg (445 lb) | ¥20.2 million | $173,600 | ¥100,000 / kg | $386 / lb | |
| 2010 | 232 kg (511 lb) | ¥16.28 million | $175,000 | ¥70,172 / kg | $343 / lb | |
| 2011 | 342 kg (754 lb) | ¥32.49 million | $396,000 | ¥95,000 / kg | $528 / lb | |
| 2012 | 269 kg (593 lb) | ¥56.49 million | $736,000 | ¥210,000 / kg | $1,247 / lb | |
| 2013 | 221 kg (487 lb) | ¥155.4 million | $1.76 million | ¥703,167 / kg | $3,603 / lb | |
| 2019 | 278 kg (613 lb) | ¥333.6 million | $3.1 million | ¥1,200,000 / kg | $5,057 / lb | |
Food
Main article: List of tuna dishes
Tuna is a popular food around the world. Fresh tuna is often served as a steak and is known for its firm texture. In many places, fresh tuna is used in dishes like salads and wraps.
Tuna is also commonly canned. It can be packed in oil, water, or sauces and is used in many meals such as sandwiches, salads, and casseroles. Canned tuna is a good source of protein and vitamin D, but it can contain mercury, so some people need to limit how much they eat.
Management and conservation
Several groups work together to manage tuna fisheries, including the Western and Central Pacific Fisheries Commission, the Inter-American Tropical Tuna Commission, the Indian Ocean Tuna Commission, the International Commission for the Conservation of Atlantic Tunas, and the Commission for the Conservation of Southern Bluefin Tuna. These groups meet to create plans to protect tuna and make fishing rules clearer.
Some tuna species, like bluefin tuna, are caught too often and need protection. Groups such as the International Seafood Sustainability Foundation and the World Wide Fund for Nature say many tuna fish are taken from fisheries that do not follow good rules. Scientists also find that warmer oceans are making life harder for tuna, especially in the Indian Ocean.
Images
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