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Bite Compass
Surf / Estuary

Blue Salmon (Blue Threadfin)

Eleutheronema tetradactylum

Blue salmon — the WA name for blue threadfin, also called Cooktown salmon or simply 'threadie'. Not a true salmon; a threadfin of the tropical north that hunts prawn and baitfish across beaches, sand flats and creek mouths from the Pilbara to the Kimberley. A hard-pulling light-tackle sportfish on the run-in tide and excellent eating.

Size
Up to 1.2m, commonly 40–70cm (captures to ~3kg common)
Peak season
Year-round in the north (best Apr–Nov)
Minimum size (WA)
No minimum size
Bag limit (WA)
4

Overview

Blue salmon is the everyday WA name for blue threadfin (Eleutheronema tetradactylum) — a slim, silver threadfin of the tropical north that's neither a salmon nor related to one. It works the beach gutters, sand flats, creek mouths and estuary channels of the Pilbara and Kimberley, hunting prawn, mullet and small baitfish on the rising tide, usually in better numbers than its larger cousin the king threadfin. It's a favourite light-tackle target on the northern beaches: a willing biter, a clean fighter that often skips across the surface, and fine eating. Like all threadfin it has a soft mouth, so a gentle take-and-lift beats a hard strike. Often caught in the same waters and on the same baits as king threadfin and barramundi.

Identification

Also known as Blue threadfin, threadie, Cooktown salmon, bluey

A slim silver fish with a blue-green sheen, a blunt fleshy snout overhanging an underslung mouth, and small eyes — plus the family's odd party trick: separate free filaments hanging below the pectoral fin, used to feel for food in dirty water. Blue threadfin have four of them, which is what tetradactylum means. King threadfin (Polydactylus macrochir) have five, a longer and more sloping head, and grow far bigger. The two are caught in the same water under different limits, so counting filaments is worth the ten seconds. Neither is any kind of salmon.

How to Catch

Best Baits

Live prawn, mullet, herring, fresh mullet fillet, strip baits

Lures

Soft plastics on 1/4–3/8oz jigheads, soft vibes, small suspending hardbodies, slow-rolled paddle-tails

Rigs

Light to medium estuarine spin gear — running sinker rig with a 3/0–4/0 circle hook and 20–30lb fluorocarbon leader, with just enough lead to hold in the wash or current. Unweighted live baits work well on the run-in. Keep drag moderate; the soft mouth tears under heavy load.

Technique

Cast plastics and small hardbodies into beach gutters and along creek-mouth sandbanks, working them slowly with the current on the run-in tide. On bait, drift a prawn or mullet through the wash and feed line on the take before lifting into the fish. Blue salmon often hold where freshwater or a creek meets the sea — fish those edges at change of light. Slide or net them rather than lifting by the line.

Best Time

April through November, peaking through the dry season when the beaches and creeks are most fishable. The last hour of the run-in before high and the first of the run-out are prime. Dawn and dusk outproduce the middle of the day.

Size & Growth

Most blue salmon off northern beaches and creek mouths are 40–70 cm and one to three kilos; a fish over 80 cm is a very good one, and the maximum runs to about 1.2 m. They grow quickly and are relatively short-lived compared with the reef fish caught nearby. Like king threadfin they change sex with age — fish start as males and the larger individuals are females — so the better fish in a school are generally the older ones. In practice a session produces numbers of similar-sized fish, because they school tightly by year class.

Diet & Habitat

Blue salmon hunt prawns, small mullet, herring and crabs, and those pectoral filaments are built for finding them in water you cannot see through — turbid, tide-stirred, run-off coloured water is exactly where they feed best. They work beach gutters, sand flats, creek mouths, tidal drains and estuary channels, pushing in on the run-in tide and dropping back with it. In WA they are a tropical fish, common through the Pilbara around Onslow, Dampier, Karratha and Port Hedland and north through the Kimberley, with the dry season the practical window. Creek-mouth seams and freshwater edges are the reliable structure.

WA Size & Bag Limits

Minimum size No minimum size
Bag limit 4
Counts toward Counts within the statewide nearshore/estuarine finfish mixed daily bag of 16.

Blue salmon is a blue threadfin, which falls under 'Threadfin, other species' in WA rules: no minimum size, bag limit 4, within the statewide nearshore/estuarine finfish mixed daily bag of 16. (King threadfin is managed separately at 450mm and a bag of 2.)

Last checked . Limits change — confirm with DPIRD before you fish.

Eating Quality

Excellent — among the better eating fish of the tropical north, and arguably better than its bigger cousin. The flesh is white, moist and mild with a fine, soft flake, at its best simply pan-fried or grilled with the skin on, or crumbed. There is little oil in it, so it dries out if you cook it hard; take it off the heat early. Smaller and mid-sized fish are the pick, since big blue salmon and big king threadfin both coarsen. The flesh is soft to begin with and gets softer in heat, so bleed on capture and get it into ice immediately — a fish left in a hot boat is a fish for the bin. It freezes only fairly, losing texture within a month or so, which is a good reason to keep what you will eat and let the rest go.

Where to Catch Blue Salmon (Blue Threadfin)

Barn Hill Station (Broome) Beebingarra Creek (Twelve Mile Creek mouth) Broome (Town Beach / Gantheaume Point / Roebuck Bay) Cape Keraudren (Pardoo) Cleaverville (Cleaverville Creek / Cleaverville Beach) Dampier (Hampton Harbour / Dampier Archipelago) Exmouth (North Ningaloo / North West Cape) Fitzroy River (Willare Bridge / Camballin / Fitzroy Crossing) Onslow (Town Beach / Beadon Creek / Mackerel Islands)

Guides Featuring Blue Salmon (Blue Threadfin)

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