Bluefin tuna

Species in Peril:

Bluefin, the largest tuna

The Atlantic bluefin tuna has small yellow fins with black edgesand has silver dots or bands on their bellies.The Atlantic bluefin tuna can grow up to 900kg and more than three meters. It is a fish lives in the open seas and it never stops swimming to ensure getting enough oxygen from the water. The continues swimming helps create heat that keeps the fish temperature compared to the surrounding water. Its swimming speed is 43 miles per hour which helps the fish to migrate from cold water where it feeds to warm water where it spawns. Bluefin tuna is hugely targeted in fishing because of the increasing use of it in the sushi market. This has risen the prices of the fish where a single fish can be sold for thousands of dollars. The Atlantic bluefin tuna lives in the Atlantic Ocean specifically in the north. It also lives in the seas near the Atlantic Ocean mainly in the Mediterranean Sea but also in the black sea and the Gulf of Mexico. Bluefin tuna mainly stays at the sea surface, but it can dive deep to 500-1000m. it prefer to stay at the surface because it is harder to forage and to control body temperature in deep water. The movement of bluefin tuna are controlled by the differences in temperatures, as well as feeding availability.

Biological features of bluefin tuna:

The Atlantic bluefin tuna mature at 4 years old in the east Atlantic and Mediterranean Sea, but it matures at 8 years old in the west Atlantic like the pacific and southern bluefin tuna. the length of the fish at maturity varies from east to west Atlantic, with east is 110–120 cm/30–35 kg and west is 200 cm/150 kg.
Bluefin tuna is a multiple spawning fish that spawn every year during the spawning season which is from mid-April to June. It spawns by eggs and the number of the eggs depends of the size and the age of the female. A 5 years old female produces about 5 million eggs compared to a 15–20 years female that can carry up to 45 million eggs. Fertilization of the eggs happens in the water and after two days of incubation without parental care, hatching happens.
The bluefin tuna larvae feeds on small zooplankton, but juvenile and adults feeds on a wide variety of prey and is able to adapt to whatever food becomes available. Bluefin tuna juveniles grow about 30cm per year which is slower than other tuna species. Then growth in length become less in adults than in juveniles, while growth in weight increases.
Bluefin tuna is a long-lived fish which means its natural mortality is low, and its higher during juvenile stages. Predation of bluefin tuna is from large pelagic sharks and killer whales. Bluefin tuna males are higher in fish nets than females and this causes lower growth for females.

Threats to bluefin tuna

Bluefin tuna fishing is very ancient, but it increased dramatically after the use of traps in commercial fisheries. Fishing was mainly targeting juvenile bluefin tuna until late 90s when large fish starts to be in demand especially by Japan. The development of bluefin tuna market affected the fishing equipment and techniques to be more powerful. This development also caused an expansion in fishery areas which yields catches of 40,000-50,000 tons a year. As a result, bluefin tuna population decreased and is labeled endangered. One of the solutions to protect bluefin tuna is putting a quota for catches of only 2,500 tons and a size limit of 6.4 kg. other solutions that the International Commission for the Conservation of Atlantic Tunas (ICCAT) has used to protect bluefin tuna are increase the minimum size andensure transfer of fish to cages from nets.

Other threats on bluefin tuna are oil spills that restrict the habitat of the fish and cause harm on the health of species. Climate change can also have an effect on the habitat of bluefish tuna. The change in the temperature of the water that gets warmer would affect migration and spawning of the Atlantic bluefin tuna.

7-10 INTERESTING FACTS

Bluefin tuna have the widest geographical distribution among species of tuna.
Bluefin tuna can live in a range of temperatures from 3 °C to 30 °C because it has stable body temperature.
Bluefin tuna adults do not feed during the spawning season.
The largest bluefin tuna is 678.58kg and it was caught in 1979.
Bluefin tuna is easily affected by fishing because of its slower growth, later maturity, shorter spawning season, larger size and longer life span.
The International Commission for the Conservation of Atlantic Tunas (ICCAT) were founded in 1966.
The eyes of Atlantic bluefin tuna are the smallest among other tuna species.

Species Name

Rhinocerotidea

Estimated Population

26,000 globally

Conservation Status

Critically endangered

Range

limited parts of sub-Saharan Africa

Reasons for Population Decline

Poaching and illegal trafficking of their horns

Trophy Hunting

Habitat loss

Species in Peril:

Bluefin tuna

Bluefin tuna

Bluefin, the largest tuna

Biological features of bluefin tuna:

Threats to bluefin tuna

7-10 INTERESTING FACTS

Species Name

Estimated Population

Conservation Status

Range

Reasons for Population Decline

Read About All of Our Species in Peril...

Subscribe to our monthly newsletter

SAFE WORLDWIDE

GuideStar is the world’s largest source of information on nonprofit organizations.

They gather and provide access to the most comprehensive, up-to-date, and accurate nonprofit information which is available to potential funders and donors.

Less than five percent of non-profits registered with GuideStar are recognized with a Gold Seal. A Gold Seal status is the leading symbol of non-profit transparency and accountability.