Scott’s Species – southern bluefin tuna, a migratory speedster

In this week’s edition of Scott’s Species, Western Angler editor Scott Coghlan takes an in-depth look at southern bluefin tuna.

Fish: Southern bluefin tuna, Thunnus maccoyii
Eating: 4 stars
Identification: Yellow bar on tail fin. Blackish-blue backs, and a silver belly with rows of light dots and lines.

Growing to almost 300kg and 2.5m in length (living up to 40 years) but not encountered at anything like that upper size in WA, southern bluefin tuna have made a remarkable comeback in Australian waters in recent years and become a key sportfish, especially along the lower east coast.

Big fish to 100kg are popping up far more regularly and there are now a band of SBT addicts that devote their time to chasing the big fish during the annual east coast run, off Victoria, NSW and Tasmania.

The SBTs encountered off WA are not as big as those found along the east coast. Picture: Perth Fishing Safaris

Highly migratory, southern bluefin tuna can be found from our North West and across the southern half of the country to lower New South Wales.

Here in WA, we usually get small fish migrating from where they were spawned in the north-east Indian Ocean and making their way across to the east coast.

Most southern blues caught in WA will be 3kg to 8kg, although fish to 20kg are not uncommon and the occasional bigger model up to 100kg does show up, but again nothing like the east coast thumpers.

Southern blues show up off Perth in good numbers most years, and schools can be found quite regularly offshore, especially during the warmer months.

They are also a common catch along the south coast, with fish caught off Albany and Esperance at the same time of year.

For boat anglers, southern bluefin are usually caught trolling, either by working likely locations or by spotting fish busting up.

Bibbed minnows around the 12cm to 14cm range are very effective on southern bluefin, as are skirted lures, and when encountered, multiple hook-ups are common.

They are a ball of muscle and fight hard for their size, with speedy runs and that typically stubborn tuna circling when close to the boat.

SBTs fight clean so heavy tackle is not required if you are prepared to be patient and indeed they can be an excellent sportfishing target on the right gear.

I would only use 6kg to 9kg line when chasing southern blues and no wire trace is needed, just a heavier shock leader.

If they are around and you specifically want to target them, then burleying up does work. Their flesh makes first-rate sashimi.

Ashley Prescott with a southern bluefin tuna from the south coast. Picture: Western Angler