Bigeye tuna Thunnus obesus
Distribution - Bigeye tuna (or bigeye) are oceanic fish present throughout Australian waters. Geographic distribution is limited by temperature and oxygen concentrations. They have a greater tolerance to lower temperature and oxygen levels than other tunas, therefore, they tend to occupy deeper waters. They are generally found in more southern waters of Australia's east and west coasts, preferring offshore areas.
Size - Bigeye tuna can reach a maximum size of 2.36 metres and 210kg in weight, however it is rare for these tuna to exceed 1.80 metres in length and 150kg in Australian waters.
Characteristics - Bigeye tuna are a member of the family Scombridae and are easily distinguished by their noticeably larger eyes, hence the name. They have moderately long pectoral fins and yellow dorsal and anal fins.
Confusing Species - Juvenile bigeye tuna are often confused with yellowfin tuna of the same size, however, the size of the eye and length of the anal fin separates these species.