They live in saltwater or marine habitats and tend to favor tropical, subtropical and temperate waters. This includes the Atlantic Ocean, Pacific Ocean and Indian Ocean. They tend to spawn between July and October, which is the time when most fisherman fish for them.
Bluefin tuna populations have declined severely from overfishing and illegal fishing over the past few decades –not just Atlantic bluefin tuna, but also Pacific bluefin tuna and Southern bluefin tuna. Population declines have been largely driven by the demand for this fish in high end sushi markets.