Bluefin tuna, scientific name Thunnus thynnus, belongs to the Scombridae family. It is the largest thunnid species, reaching up to 3 meters of length and 600 kg of weight.
Bluefin tunas have long but rounded, spindle-like bodies covered in scales.
They have large heads and they have smaller eyes than other tunas. The back is deep blue and the belly is silver white. The first dorsal fin is yellow or blue, the second one red or brown. The anal fin and the finlets are dark yellow rimmed white. The second dorsal fin is taller than the first on and the pectoral fins are very short. The caudal fin is arch-shaped. The body structure of the bluefin tuna makes it a very efficient swimmer.
Bluefin tunas migrate for alimentary and reproductive reasons. During their long migrations, they withstand large water temperature variations which they can tolerate thanks to their ability to keep their body temperature above that of their medium.
Bluefin tuna is a pelagic species that forms schools. It can be found both near the water surface and in depths of up to 1000 meters.
It inhabits the whole pelagic ecosystem in the north Atlantic and adjacent seas, mainly the Mediterranean.
It feeds on fin fish (mainly herring, anchovy, sardine, horse mackerel, mackerel), crustaceans and cephalopods.
Reproduction takes place in two general areas, e.g., the Mediterranean Sea and the Gulf of Mexico, between the months of May and July, depending on each specific spawning ground. In the Mediterranean six such spawning grounds are known and identified by ICCAT.
Different concurrent ecological and environmental variables affect the choice of a particular spawning ground by the tunas. Those spawning in the Mediterranean reach sexual maturity at around age 4. At a water temperature of 24 C, embryo development is completed in approximately 32 hours and the larva phase in approximately 30 days.