King Threadfin Salmon
Surf / EstuaryKing threadfin salmon are a large inshore predator of WA's North Coast — Eighty Mile Beach, Cambridge Gulf and the Pilbara estuaries, not Perth. Not a true salmon despite the name; a threadfin closer in habits to mulloway, hunting beach gutters and creek mouths on the rising tide. Soft mouth, easy to bust off.
Overview
King threadfin are one of the great beach and estuary species of tropical WA — long-bodied, silver, with the distinctive trailing pectoral filaments that give the family its name. They patrol surf gutters, sand flats and creek mouths from the Pilbara through Eighty Mile Beach and into the Kimberley, hunting prawn, mullet and small baitfish on the run-in tide. Eighty Mile Beach is the iconic shore-based fishery, with Wyndham and the Cambridge Gulf creeks producing fish from boats. They have notably soft mouths, so a soft strike and steady pressure beat a hard hookset. Often caught alongside blue threadfin in the same waters.
Identification
Threadie, king salmon, threadfin salmon
A long silver fish with a deeply forked tail, a blunt overshot snout and the mouth set underneath — built for grubbing prawns off sand rather than chasing bait down. The family marker is the free pectoral filaments trailing below the pectoral fin: king threadfin usually carry five of them, blue threadfin four, and counting is the quickest way to tell the two apart in the same gutter. King threadfin also grow far larger and have a longer pectoral fin. Against mulloway the split is easy — mulloway have a terminal mouth, no filaments, and none of the trailing threads. Anglers just say threadies.
How to Catch
Live mullet, prawn, fresh mullet fillet, herring, strip baits
Soft plastics on 1/4–1/2oz jigheads, suspending hardbodies, soft vibes, slow-rolled paddle-tail plastics
Running sinker rig with a 4/0–5/0 circle hook and 30–40lb fluorocarbon leader on the beach, with enough lead to hold in the surf. From a boat or creek bank, a lighter unweighted live-bait rig works well on the run-in tide. Avoid heavy drag — soft mouths tear out under load.
On Eighty Mile Beach, find a deeper gutter close to the sand and fish baits or plastics across the rising tide. In the creeks, cast plastics and hardbodies into the run-out at change of light, working them slowly along the sandbank edges. Keep drag moderate and pressure steady once hooked — they'll often head back into the wash, which is fine if you don't over-tighten. Use a long-handled net or a slide on the beach; lifting them by the line will tear the hook free.
April through November is prime, covering the dry-season tourist window when the beaches and estuaries are fishable. Run-in tides in the last hour before high are the standout window, with the first of the run-out also productive. Dawn and dusk consistently outproduce midday.
Up to 1.5m and 20kg, commonly 60–90cm
Apr–Nov (dry season peak)
Size & Growth
Commonly 60–90cm and a few kilos, with metre-plus fish the mark of a good session and the biggest running past 1.5m and 20kg. Like barramundi they are protandrous, maturing as males and turning female at larger sizes, so the big fish on the beach are breeding females and worth the release. They are longer-lived and slower-growing than their size suggests, which is part of why the bag is 2. A 45cm legal fish is a young male and a modest feed rather than a trophy.
Diet & Habitat
Prawns first, then mullet, small baitfish and crabs, worked out of turbid water by feel rather than sight — which is why they thrive where visibility is nil. They hold in deeper surf gutters hard against the sand, on sand flats, at creek mouths and in the run-out channels behind sandbanks, moving up with the rising tide and dropping back with it. WA range runs from the Pilbara estuaries through Eighty Mile Beach and into the Kimberley and Cambridge Gulf, with Eighty Mile Beach the iconic shore fishery and Wyndham the boat-based one.
WA Size & Bag Limits
| Minimum size | 45 cm |
|---|---|
| Bag limit | 2 |
| Counts toward | Counts within the nearshore/estuarine finfish mixed daily bag of 16. King threadfin carry their own size and bag limit, separate from blue and other threadfins. |
Minimum size: 45cm (450mm). Bag limit: 2 individually, counted within the nearshore/estuarine finfish mixed daily bag of 16. King threadfin (Polydactylus macrochir) carry their own size and bag limit separate from blue and other threadfins. Possession limit applies.
Eating Quality
Excellent — moist white flesh with a mild, clean flavour that holds together on the grill and does not fall apart in a pan, which puts it on a par with mulloway and ahead of most northern beach fish. Bleed at the gills and get it into an ice slurry immediately; threadfin flesh softens fast in tropical heat and a fish left in the sun for an hour is a different product. Fillets skin-on and grill or pan-fry them, or crumb the smaller fish. The larger breeders are still good but coarser, and given they are females it is worth photographing and releasing them rather than filling the esky. Freezes reasonably well vacuum-sealed for a month or two, though the texture softens slightly on thawing.
Perth Tips
Eighty Mile Beach Caravan Park is the obvious base for shore-based threadfin fishing, with the run-in tides on the new and full moons producing the best of it. Wyndham and Kununurra charters target threadfin alongside barramundi in the Cambridge Gulf creeks. Don't over-strike — feed line briefly on the take, then lift into the fish.