Yellowfin Tuna
Offshore / BluewaterYellowfin tuna are WA's premier light-tackle gamefish — chased off Exmouth, Ningaloo and the continental shelf, and again off Rottnest and the lower west coast in autumn. Blistering runs, prime sashimi flesh, and a large-pelagic bag of 3.
Overview
Yellowfin tuna are the blue-water benchmark for WA gamefishers. The North West Cape out of Exmouth is the headline fishery — the shelf and the canyons drop into deep water within a short run, and yellowfin to 60kg-plus show from autumn into the cooler months. Off the metro coast, autumn brings schools onto the shelf out wide of Rottnest, and the south coast off Albany and Esperance produces them alongside southern bluefin. They hunt in fast-moving schools, often under working birds and bait balls, and a hooked fish will dump 200m of line before you've found your feet.
Identification
Yellowfin, ahi
Yellowfin are separated from WA's other tunas by their fins. Adults grow long, sickle-shaped second dorsal and anal fins that sweep back towards the tail — unmistakable on a big fish — plus a row of bright yellow, black-edged finlets along the top and bottom of the tail wrist. The body is metallic dark blue above, silver below, with faint pale vertical lines on the flanks. Southern bluefin are stockier, with short fins, a blue-black back and a distinctly yellow keel at the tail. Longtail tuna are slimmer, with pale oval spots low on the belly. Small yellowfin are the hardest call — check the finlets.
How to Catch
Live slimy mackerel and yakkas, whole pilchards and gar for cubing/berley trails, skipping garfish behind the boat
Skirted trolling lures (Pakula, Zacatak) in 6–8 inch on the shelf, chrome slugs and stickbaits cast into surface bust-ups, deep-diving minnows along temperature breaks
Heavy spin (10000–14000 reel, 50–80lb braid) or 24kg overhead for trolling, 1.5–2m of 80–130lb fluorocarbon leader, strong single or circle hooks. Check drags and crimps before you leave the ramp — yellowfin punish weak gear.
Troll skirts and divers along the shelf edge, current lines and temperature breaks, and watch the sounder and the birds. When fish bust up on the surface, shut down and cast slugs or stickbaits ahead of the school. A cube or berley trail anchored on the shelf will hold fish under the boat. Keep the boat moving with a hooked fish to stop it sounding.
Autumn and early winter are prime off the lower west and south coast; the Exmouth grounds fish year-round with a cooler-months peak. Early morning around bait schools and current changes is the most reliable window.
Commonly 15–40kg; fish over 60kg off the Exmouth and Ningaloo grounds
Year-round in the north; autumn–winter peak off the lower west coast
Size & Growth
Most WA yellowfin are 15–40kg. Off Exmouth and the North West Cape, fish over 60kg are a real prospect, and the species goes well over 100kg globally. Off the metro shelf and the south coast, schooling fish of 10–25kg are the normal encounter and a 40kg-plus fish is a very good one. They grow extremely quickly, putting on serious weight in their first few years, and they don't live especially long compared with a southern bluefin. Expect a school to be one size class: the fish working under the birds are usually all much of a muchness.
Diet & Habitat
Yellowfin are fast, wide-ranging open-ocean predators, taking pilchard and other small pelagic baitfish, squid, flying fish and pelagic crabs, hunting in schools that push bait to the surface under working birds. They live in the blue water off the shelf edge, along canyons, temperature breaks and current lines, and around floating structure and bait schools, working from the surface down. In WA the shelf runs close in off the North West Cape, which makes Exmouth the headline access; off Perth they're a run out wide of Rottnest, mainly in autumn, and the Albany and Esperance canyons produce them alongside southern bluefin.
WA Size & Bag Limits
| Minimum size | No minimum size |
|---|---|
| Bag limit | 3 — the statewide large pelagic finfish total mixed bag |
| Counts toward | Counts within WA's large pelagic finfish total mixed bag of 3 per fisher, shared with mackerel, mahi mahi, the other tunas, wahoo and samsonfish. A Recreational Fishing from Boat Licence is required from a powered boat. |
No minimum size. Yellowfin tuna count within WA's large pelagic finfish TOTAL mixed bag of 3 per fisher (statewide) — shared with mackerel, mahi mahi, the other tunas, wahoo and samsonfish. A Recreational Fishing from Boat Licence (RFBL) is required when fishing from a powered boat.
Eating Quality
Yes — yellowfin is prime eating: deep-red, firm, clean-flavoured flesh that is superb as sashimi, excellent seared rare, and good on the grill if you don't overcook it. Past medium it goes grey, dry and chalky. Bleed and ice the fish the moment it's aboard, ideally spiking it first; quality drops fast in a tuna left to flap on the deck, and a slurry beats dry ice every time. Trim the bloodline before serving. Smaller school fish are leaner and cleaner; bigger fish carry more fat through the belly and make the better sashimi. It freezes poorly next to a white fish — colour and texture both go — so vacuum-seal the loins and use them within a couple of months. Large tuna do accumulate mercury, so treat it as an occasional meal rather than a weekly one.
Perth Tips
A run out of Exmouth puts you on the shelf inside half an hour — there are few easier blue-water accesses in Australia. Watch for birds and surface activity rather than just trolling blind. Keep a spin rod rigged with a slug for the surface schools that appear without warning. Handle and chill the fish properly and a single yellowfin is a freezer's worth of sashimi.