Bluefin tuna corresponds to the species Thunnus thynnus. It has a characteristic torpedo shape and has an average size of two meters long, although there are records of specimens of 4.5 meters and more than 700 kilos.
Geographic distribution of bluefin tuna
Bluefin tuna is widely distributed by Atlantic and Pacific oceans in subtropical and temperate waters.
Bluefin tuna habitat
This bluefin tuna is epipelagic, oceanic – that is, It lives from the surface to about 100 meters deep, where most of the marine life is concentrated – and arrives near the coast seasonally. It can tolerate a considerable range of temperatures.
Bluefin tuna exhibits strong school behavior when they are young. Bluefin tuna schools migrate seasonally northward during the summer months, along the coast of Japan and the Pacific coast of North America.
It is known for studies in tagged fish that can perform transpacific migrations. Other studies of tagged fish have shown that a bluefin fish can cross the Atlantic in less than 60 days.
Physical features of bluefin tuna
Compared to other tunas, this fish He has a long and somewhat pointed head and the eye is small. These fish are strong and fast swimmers.
Two dorsal fins are present, with a small space that separates them. The second dorsal fin is taller than the first and is followed by 7 to 10 fins. Three keels are present in the caudal peduncle.
Coloration
The body of the bluefin tuna is a deep metallic blue on the back while the lower sides and belly are silvery white. It also has bars and faint spots on its sides.
The first dorsal fin is yellow or blue, while the second is red or brown. The anal fin and the fins are yellow, with black borders.
Eating habits of bluefin tuna
As a predator, this fish exhibits different strategies, depending on its objective prey. Use a quick and energetic search to get smaller, particularly anchovy, farmed fish. It also usually catches small and slow-moving organisms.
It has been recorded that the feeding of bluefin is very varied. Mainly consume anchovies and sardines, but also mackerel, flying fish, squid, shrimp and eels, as well as smaller tunas. In areas near the coast eat starfish, seaweed and smaller fish from shallow water.
Reproduction
Bluefin tuna is oviparous. Spawning has been detected in areas and seasons like the Mediterranean, from June to August, and in the Gulf of Mexico, from April to June.
In the Pacific, spawning occurs in the Philippines. This is a limited spawning area compared to other tropical tunas.
Little is known about the spawning of bluefin tuna, as it has not been observed. Differences in spawning seasons could be due to any of a number of factors., including different environmental signals or the genetic variation itself.
One factor to consider would be the temperature: in the Gulf of Mexico spawning occurs at temperatures of 24.9 to 29.5 ° C, while in the Mediterranean it occurs at 19-21 ° C.
In captivity the blue fin reaches sexual maturity at three years. However, others have suggested that bluefin tuna becomes sexually mature at the age of four to five years.
Conservation of this species
The popularity of this tuna in international markets has led to intense exploitation in several areas, especially in the North Atlantic Ocean.
Because this fish migrates long distances, and because much of the fishing is done in international waters, international cooperation is necessary in the conservation management decisions of this species.
Since 1966, there is the International Commission for the Conservation of Atlantic Tunas to specifically address conservation problems that face bluefin tuna and other highly migratory species.
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