Also known as
- Ahi US
Identification
A massive worldwide tropical and subtropical tuna with a deep stocky torpedo build engineered for sustained deep-water hunting and devastating long runs.
- Deep metallic blue-black back, silvery-white belly
- Yellow finlets edged with black
- First dorsal yellow; second dorsal and anal fins yellow with black margins
- Exceptionally large eyes — the largest of any tuna
- Heavily built across the shoulder relative to length
Where it holds
- Offshore
- Oceanic
Behaviour
A pelagic adapted to extreme vertical foraging — daytime hunts at 200-500m on deep cephalopods, lanternfish, and crustaceans, then ascends to 0-100m at night following bait migrations. Specialised heat-exchange systems and exceptionally large eyes enable sustained deep cool-water hunting. Schools by size and associates with floating objects, seamounts, FADs, and current convergences. Peak activity at dawn and dusk transitions. Highly migratory across ocean basins.
Diet: Lanternfish, Small Mackerel, Scad, Flying Fish, Squid, Deep Water Shrimp
How it's caught
Line Fishing
Trolling
The dominant approach worldwide — particularly the US Northeast canyons, Hawaii, the Azores, and the Caribbean. Pull a spread of large skirted lures, jet heads, and rigged ballyhoo at 6-9 knots along thermocline edges, seamounts, and current convergences. Deep-diving plugs reach 30-50m where fish often cruise. Daisy chain teasers raise fish from depth. 24-60kg gear with non-offset circle hooks. Dawn and dusk produce best.
Chunking
A productive offshore canyon and seamount approach — particularly US Northeast (Hudson, Block, Atlantis canyons), the Azores, and Hawaii. Anchor or drift over deep structure and establish a chum slick of cut mackerel, squid, or sardines. Drop unweighted chunks on 10/0-12/0 non-offset circle hooks back through the slick. Best in low-light and new-moon windows when fish rise from depth.
Live Lining
Devastating when bait schools concentrate fish at FADs, seamounts, and floating debris. Slow-troll or drift a live skipjack, bonito, mackerel, or squid on a 10/0-12/0 non-offset circle hook. Bridle the bait. Kite fishing keeps baits in the surface zone during low-light feeding windows. Heavy 37-60kg gear.
Jigging
Deadly daytime approach when fish hold at 100-300m on seamounts, drop-offs, and FAD anchor lines. Drop a 250-500g knife jig or slow-pitch jig and rip with sharp cadence sweeps; many strikes come on the flutter fall. PE5-8 braid with 5-7m of fluorocarbon topshot.
Spear Fishing
Bluewater Spearfishing
An elite-tier worldwide bluewater target — daytime depth (50-150m) keeps encounters rare. Best opportunities are at FAD pinnacles, seamount tops, and dawn/dusk surface windows in 20-50m. Use a 130-150cm bluewater speargun with 8.0mm shaft, slip-tip, breakaway rig, and 100L+ float system. Fish are curious but wary — flasher and chum bag help draw them in.
