Bigeye Tuna
Bigeye tuna are a deep-water pelagic species found in New Zealand waters year-round, though more widely distributed north of the Taranaki Bight through summer.
Bigger and heavier-bodied than yellowfin, they're caught by recreational anglers targeting deep offshore grounds, and are frequently confused with yellowfin until you get a close look.
Their size and the depth at which they feed make them a serious offshore target.
Scientific Name: Thunnus obesus
Also known as Bigeye, BET, ahi (Hawaiian term used in NZ fishing circles)
- Dark metallic blue on the back, fading to white on the belly; golden-yellow flanks visible when the fish is fresh out of the water.
- Distinctly large eyes — noticeably bigger than a yellowfin of similar size — the most reliable field ID feature when the two species are compared side by side.
- Barrel-shaped, deep body; pectoral fins are very long, reaching well past the second dorsal fin in juveniles.
- Bright yellow finlets with black edges; first dorsal fin deep yellow. Common catches run 20–80 kg; fish over 100 kg are taken in NZ waters.
What to know
Habitat Distribution
- A wide-ranging oceanic species present in NZ waters year-round; more broadly distributed north of the Taranaki Bight during summer months.
- Juveniles are mainly recorded off the southwest coast of New Zealand; adults roam deeper offshore grounds across the north and northeast.
- Strongly associated with deep water — routinely caught at 200–400 m, well below the depths where yellowfin typically feed.
- Found in warm to temperate open ocean; tends to follow temperature gradients and current edges rather than staying in fixed locations.
Key Locations
- North of the Taranaki Bight — the main summer distribution zone for bigeye in NZ recreational waters.
- Offshore grounds north and northeast of the North Island, where warm current edges concentrate bait and draw pelagics including bigeye.
- Southwest coast — juveniles are recorded here, though adult fish are primarily targeted further north in deeper offshore water.
Specific Spots
- Deep water column — bigeye feed well below the surface, often at 200–330 m, so targeting them means fishing baits or lures at serious depth rather than near the top.
- Temperature breaks and current edges offshore attract bait concentrations that pull bigeye up from depth, especially at dawn and dusk.
- Dolphins working the surface can indicate bigeye activity below — the same bait schools that attract dolphins often hold tuna underneath.
- At night, bigeye move shallower as prey species rise in the water column, making them accessible to deep jigging from anchored or drifting boats.
Bigeye Tuna FAQ
Answers from onWater's species guide.
What are the best lures and bait for Bigeye Tuna?
Whole rigged baits, squid, skipjack, large pilchards, fished deep on a wire or heavy fluorocarbon trace are the most consistent producers; the bait needs to reach 200 m or more to be in the zone during daylight.
When is the best time to fish for Bigeye Tuna?
Present year-round in NZ waters, but more widely distributed and accessible north of the Taranaki Bight through summer (roughly December–April). Night jigging opportunities increase when fish move into shallower water after dark, this can occur across seasons wherever bigeye are present offshore.
How do you catch Bigeye Tuna?
Most NZ recreational bigeye fishing is done from charter or private game boats working deep offshore grounds, either deep-dropping whole baits to 200–330 m during the day or vertical jigging at night when fish move shallower. It's a targeted, deliberate fishery, not a by-catch of surface trolling.
What do Bigeye Tuna eat?
Bigeye feed on squid, deep-water fish, and crustaceans, their large eyes are an adaptation for hunting in low-light, deep-water conditions where prey is harder to see. Deep-set baits (whole squid, skipjack, or large pilchards) fished at depth directly imitate this forage.
Where do Bigeye Tuna live?
A wide-ranging oceanic species present in NZ waters year-round; more broadly distributed north of the Taranaki Bight during summer months. Juveniles are mainly recorded off the southwest coast of New Zealand; adults roam deeper offshore grounds across the north and northeast.
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