Fishing the Mackerel Islands off Onslow: A Destination Guide

There’s no road to the Mackerel Islands and no public ferry running in 2026. You get there one of three ways: your own boat across from Onslow — roughly a 45-minute run over 22km of open water — a charter from Onslow or the island, or a light plane into Thevenard from Exmouth (about 35 minutes) or Onslow (around 10). The own-boat option is the cheapest and the most committing; this is exposed Pilbara water, and the crossing demands a seaworthy boat and a real weather window.

Thevenard Island is the hub. It carries a row of self-contained, air-conditioned beachfront cabins, which is what turns this from a day mission into a proper destination — you fish hard, then sleep 50 metres from where the boat’s moored. Direction Island, the other half of the operation, is closed for the 2025/26 season, so plan around Thevenard. The accommodation season runs roughly April to October, deliberately sitting either side of the worst of the cyclone window.

The headline is pelagic. Spanish mackerel hold on the current lines and bommies and crash a trolled bait with the kind of reel-scream that ruins you for jetty fishing. Around and under them you’ll find giant trevally and golden trevally working the shallow reef, queenfish busting bait on the flats and creek mouths, cobia cruising isolated structure, plus tuna and wahoo through the warmer water. The shelf isn’t far off, so the gamefishing extends to sailfish and the odd marlin for boats willing to push out and troll the blue.

Drop a rig to the bottom and a different fishery opens up. The reefs hold serious demersals — red emperor, coral trout, rankin cod, spangled emperor and bluebone all come up on the same drifts. That mix is the real draw: a single day can run from trolling for Spaniards in the morning to bottom-bouncing reds over rubble in the afternoon. Timing is governed less by a calendar than by the wind — the cooler months from autumn through spring give the most settled water, and sailfish lean toward spring and early summer. Up here the fishing follows the weather window, not the other way around.

The Spanish mackerel is the fish on the sign, and it earns it. They run to 20kg-plus, hit a trolled lure or rigged bait at speed, and the first run off an overhead reel is the reason people book the trip in the first place. They sit on the productive bommies and pressure edges year after year, so the local knowledge a charter brings is worth real money.

For sheer violence, the giant trevally is the other marquee fish. GTs patrol reef sometimes skinny enough to see their backs out of the water, and the strike on a surface popper is among the most brutal in fishing. They fight dirty, run straight for coral, and test every knot and split ring you own. Most are tagged and released — eating quality drops off in big fish, and there’s a ciguatera risk in tropical reef predators — so this is a sport fishery, not a feed.

Match the tackle to the job and bring two setups. For the pelagics, a 15kg overhead or heavy spin outfit, 50–80lb braid, and a single-strand or heavy mono bite trace — mackerel teeth go through ordinary leader like cotton. Troll hard-bodied minnows, skirted lures or rigged garfish at 6–8 knots along current lines and reef edges. For trevally and queenfish, a stickbait-and-popper spin outfit with 40–50lb braid lets you sight-cast schools busting bait at change of light.

For the demersals, switch to a paternoster rig with 8/0–10/0 circle hooks on heavy droppers, an 80–100lb leader, and enough lead — often 16oz and up — to hold bottom in current. Reds and bluebone bury into structure on the strike, so it’s a fast, hard lift. Big baits keep the pickers off: whole squid, flesh strips and pilchard. A descender or release weight is standard kit up here — demersals suffer barotrauma from depth, and a surfaced fish is a wasted one.

The simplest way in is a charter package out of the resort — a centre-console running up to six anglers, gear and bait supplied, with a skipper who already knows the marks. Packages bundle cabin accommodation with the boat days, which suits a group splitting the cost. Bringing your own boat is cheaper per head and gives you freedom, but it puts the crossing, the reef knowledge and the safety margin on you — log a trip plan, carry the right gear, and don’t push a marginal forecast across 22km of Pilbara water. Either way, book ahead: cabins on Thevenard are limited and the good-weather months fill.

The Mackerel Islands sit in the North Coast Bioregion, and the rules here are not the rules most Perth anglers carry in their heads. There’s no West Coast demersal closure up north, the demersal mixed-bag arrangement differs, and pelagic limits — including for Spanish mackerel — have their own settings that have been adjusted in recent reforms. Don’t take numbers off a charter mate, an old guidebook, or this article. Read the current bag, size and possession limits at DPIRD before the trip, and screenshot them — mobile reception out on the islands is patchy at best. Demersals like red emperor and bluebone are slow-growing and tightly managed for good reason; fish to the current numbers, weight your releases back to depth, and the fishery stays worth the airfare.