Bigeye Tuna

Physical Description

Bigeye tuna are generally smaller than bluefin and larger than yellowfin.  They reach a maximum size of 6 feet, weigh up to 460 pounds, and can live as long as 10 to 12 years.  They are long and streamlined, dark metallic blue on their backs and upper sides, and have nearly white lower sides and belly. 

Habitat and Distribution

Bigeye are a highly migratory species found throughout the Atlantic and Indian Oceans between 30 degrees north and 20 degrees south.  They can be found from the surface to 800 feet deep, depending on the age of the bigeye and where prey can be found.  Bigeye have been known to dive for prolonged periods, going as deep as 1,500 feet.

Diet

Bigeye tuna are opportunistic feeders that prey on smaller fish, crustaceans, and squid.

Reproduction

Bigeye tuna reach reproductive maturity around age 3, and at around 3 feet in length. They spawn throughout the year in tropical waters. 

Threats

Bigeye tuna are prized in Japan for sashimi as well as frozen and fresh in other markets.  As bluefin tuna populations shrink around the world, pressure on bigeye fisheries are increasing.  Juvenile bigeye tuna are increasingly caught as bycatch in skipjack tuna fisheries because juvenile bigeye school with skipack.

Policy

Bigeye fisheries are managed by

• The International Commission for the Conservation of Atlantic Tuna (ICCAT) in the Atlantic Ocean
• The Indian Ocean Tuna Commission (IOTC) in the Indian Ocean
• Western and Central Pacific Fisheries Commission (WCPFC) in the Western Pacific Ocean
• The Inter-American Tropical Tuna Commission (IATTC) in the Eastern Pacific Ocean