Bigeye Tuna (Thunnus Obesus)

Bigeye Tuna (Thunnus Obesus) were long considered to be a subspecies as the yellowfin. However their anal fin and second dorsal fin will never reach nearly the same length as that of a yellowfin. All its fins (except for the pectorals) may have varying degrees of yellow coloration. The most notable characteristic is their stocky bodies and large eyes.

Like the other tuna, this is a highly migratory fish. They will cover wide distances throughout the year, however scientists still lack enough understanding about bigeye to properly determine any patterns.

As the name bigeye suggests, these schooling fish spend most of their time deep beneath the ocean’s surface. During daylight hours, they will stay at depths of roughly 100 feet. This differs greatly from that of bluefin and yellowfin that spend their day around 15 feet deep.

Bigeye will eat the same basic fish as bluefin but are rarely seen chasing their meals at the water’s surface.

Bigeye commonly grow to 100 pounds in the North Atlantic. Very little is known about their life span.

Bigeyes’ depth make them difficult to target. Anglers will normally troll baits or lures around 100 feet deep at night, but bigeye are considered an unreliable target fish — even with a full moon. Like the other tuna, bigeye are strong swimmers who will sound when hooked.

Their meat is on par with that of bluefin and yellowfin tuna. As such, the same preparations as a bluefin should be made when boating a bigeye. It is recommend to bleed bigeye once boated. This is done by cutting a deep slit behind the fish’s gills. It is also recommended to leave the catch laying on one side and to never roll it over. This way, the remaining blood will settle on the lower half of the fish’s body. This gives the meat on the upper side a cleaner flavor. The lower side can still make for good table fair, but is not recommended for sushi.

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