A heavy-shouldered tuna with a big eye, built to hunt in deep, dim water. Most eastern Pacific bigeye live far to the south of us, so off Cabo it’s an occasional fish, and a big tuna here is far more likely to be a yellowfin. Knowing the difference matters.
Dark metallic blue back, white lower sides and belly, and in live fish an iridescent blue band along the side. The first dorsal fin is deep yellow, the second dorsal and anal fins are pale yellow and never grow long like a big yellowfin’s, and the finlets are yellow edged with black. The body is deep and rounded, the head and eye are large for the fish’s length, and on fish of about 45 to 100 cm the pectoral fin is long, thin and flexible, reaching past the base of the second dorsal. The surest sign is inside: the underside of the liver is striated.
Bigeye live in tropical and subtropical waters of the Atlantic, Indian and Pacific oceans, but not the Mediterranean. They tolerate water of 13 to 29 °C (55–84 °F) and do best around 17 to 22 °C. Juveniles and small adults school at the surface, often with skipjack and young yellowfin, and gather under floating objects; adults stay deeper. In the eastern Pacific, purse seiners rarely catch them north of about 10°N: in 2024 almost all were taken between 10°N and 15°S.
They eat fish, squid and crustaceans, by day and by night. Bigeye grow fast, reach about 2 m (6.5 ft) and mature at about 3 years and roughly 100 to 125 cm. In the tropics they spawn all year, around the full moon, as often as every day or two, releasing millions of eggs each time. NOAA gives a life span of 7 to 8 years; FishBase reports a maximum age of 17.
Lift the liver on a cleaned tuna: a bigeye’s has three rounded lobes of about equal size and a striated underside. A yellowfin’s is smooth, with a longer, thinner right lobe. It’s the check fisheries observers trust most.
Source ↗Archival tags on 96 bigeye in the equatorial eastern Pacific showed them spending nights almost entirely above the thermocline, at an average of 34 m, and much of the day below it, at average depths of 163 to 183 m.
Source ↗In a 46 cm bigeye the swim bladder is large and fills almost the whole body cavity. In a yellowfin the same size it sits only in the front half and is usually deflated.
Source ↗In IATTC purse-seine records from 1976 to 1981, bigeye were virtually absent between 10°N and 25°N. A few were caught off Baja California between 28°N and 33°N, almost all in July to September.
Source ↗Until the 1990s, longliners caught almost all the bigeye in the eastern Pacific. Since 1996 the main catch has come from purse seiners setting on floating objects, which take mostly small bigeye.
Source ↗The Pacific all-tackle record, 435 lb (197.31 kg), was caught on April 17, 1957 off Cabo Blanco, Peru, by Dr. Russel Lee. The tuna took a bonito.
Source ↗Off Cabo, bigeye are an occasional fish at best: decades of tuna-fleet records show almost none between 10°N and 25°N, and Cabo sits at about 23°N. Nobody can plan a trip around them. They usually run deep during the day, so they are more often hooked on baits and lures fished deep, or around dawn, dusk and floating objects, where they come shallower.
If you land a big tuna and think it’s a bigeye, look at the eye, the body depth and the second dorsal and anal fins, then confirm with the liver when the fish is cleaned. A bigeye counts toward the same daily limit as any other tuna.
Excellent eating. Bigeye has a higher fat content than yellowfin and is prized for sashimi, especially in Japan.
| Daily limit (NOM-017-PESC-1994) | Up to 5 per angler per day, within the 10-fish total |
|---|---|
| IUCN Red List | Vulnerable (assessed 2021) |
| Eastern Pacific stock (2024 assessment) | Not overfished and not subject to overfishing, according to NOAA; the IATTC manages it with purse-seine closures and longline catch limits |
| IGFA all-tackle record (Pacific) | 435 lb 0 oz (197.31 kg), Cabo Blanco, Peru, 1957 |
The yellowfin tuna is the fish to rule out. Large yellowfin grow very long, sickle-shaped second dorsal and anal fins; a bigeye’s never do. A yellowfin is slimmer, with a smaller eye and head for its length, a stiffer pectoral fin that reaches only to the second dorsal, bright yellow finlets, and on smaller fish rows of pale vertical lines and dots on the lower sides. The center of a yellowfin’s tail usually forms a V or M-shaped notch, where a bigeye’s is flat or slightly cupped. When in doubt, the liver settles it: striated in bigeye, smooth in yellowfin. Small bigeye also have very long pectoral fins, as long as an albacore’s.
Look for a deeper, rounder body, a bigger eye and short second dorsal and anal fins. To be sure, check the liver: a bigeye’s has striations on its underside, a yellowfin’s is smooth.
Yes, but not many. Most eastern Pacific bigeye are caught well to the south, and off Cabo they are only an occasional catch. Most big tuna here are yellowfin.
Up to 5 per angler per day, within the overall limit of 10 fish.
Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.
Sportfishers with the range to reach the offshore banks. From $799 with license included.
