Yellowfin tuna are the benchmark of east coast offshore fishing. Fast, powerful, and unforgiving of gear weakness. An account of a two-day trip to the shelf break off Bermagui.
The Plan
The shelf break off Bermagui on the NSW South Coast sits about 35 nautical miles offshore, where the seafloor drops from a few hundred metres to over 2,000 metres in the space of a few kilometres. This abrupt depth change concentrates baitfish along the edge and draws the pelagic predators — yellowfin tuna, striped marlin, mahi-mahi, and wahoo — that follow them. In summer, when the East Australian Current pushes warm blue water close to the break, the fishing can be exceptional.
We were three anglers on a privately owned 7.5-metre centre console with twin 200hp outboards — capable of reaching the shelf comfortably in reasonable conditions and fast enough to run home if the weather changed. The forecast showed a two-day window between weather systems, which is about the best you get in summer on the South Coast. We left the harbour at 4am to reach the break at first light.
The Run Out
Two hours at 28 knots in the dark. The ocean outside the heads was a metre and a half with a 12-second interval — acceptable, if not comfortable. By the time the shelf change registered on the sounder and the water colour shifted from green to the deep blue of offshore water, the sun was just above the horizon and the conditions had laid down to near-flat.
The first sign of tuna was birds — gannets working a disturbance on the surface about two kilometres to the north. Gannets diving indicate baitfish being pushed up from below, which almost always means large predators underneath. We ran to them at speed, cutting the engines 300 metres out to avoid spooking the fish.
The First Strike
We rigged for casting — 6000-series spinning reels loaded with 50lb braid, 80lb fluorocarbon leader, and 60g knife jigs in chrome and blue. The bait school was visible from the surface — a dark, roiling mass of slender fish about the size of a hand being pushed up and decimated from below.
The first cast landed at the edge of the bait school and the jig had sunk perhaps three metres before the line went tight with a force that was not gentle. A yellowfin tuna in the 25-30kg range does not merely run — it accelerates with a sustained power that drains a reel at a speed you have to experience to believe. The first run took about 90 metres of line in under 10 seconds. The drag, set at 8kg of resistance, barely slowed it.
The fight lasted 22 minutes. The fish ran three times, sounded twice into water over 800 metres deep, and showed an endurance that was not declining when we finally got colour on it. A yellowfin of about 28kg, chrome-flanked and perfectly proportioned, alongside the boat. We gaffed it cleanly, brought it aboard, and killed it immediately.
The Day
We worked the shelf break for six hours that first day. The tuna school was present until around 10am, then dispersed as the sun rose high and the birds dispersed. In that window we boated four yellowfin between 18 and 32kg, lost three hookups to straightened hooks and one to a clean break of the leader at the boat — the result of a fish that turned back under the hull at boatside and got the leader over the transom corner.
The afternoon produced mahi-mahi on floating weed lines — three fish between two and four kilograms that hit surface poppers cast alongside floating kelp and timber. Mahi are different fish from tuna: faster to the surface, more acrobatic, easier to fight, and excellent eating. We kept all three.
The Second Day
Conditions deteriorated overnight. Two metres at nine seconds by dawn — workable but uncomfortable. We ran out anyway and found the shelf largely quiet. A single yellowfin school appeared mid-morning and produced two fish before disappearing. We were back in the harbour by 2pm ahead of the building swell.
Total across two days: six yellowfin tuna and three mahi-mahi. Approximately 100kg of fish. We kept what we could use and gave the remainder to other boats in the harbour who had not been out.
What It Requires
Offshore fishing at this scale requires a capable boat and an experienced operator who understands the weather, the mechanics, and the specific risks of offshore work on the NSW coast. The margin for equipment failure 35 miles offshore in a small boat is narrow. Everything needs to work reliably. EPIRB registered and activated, flares current, VHF radio operational, and a detailed float plan lodged with someone ashore are the non-negotiables before any offshore departure.
UV protection for a full day on open water is essential. Browse our offshore fishing clothing range — long-sleeve UPF 50+ shirts, broad-brim hats, and polarised glasses for open water.
