Marlin 101: Catching Inshore Baby Blacks

The black marlin is one of the most highly regarded and pursued game fish on the planet, renowned for its blistering runs, multiple jumps and tail walks during battle they are capable of speeds up to 130 kms an hour.

With a more solid build, relitvely short bill and lower rounded dorsal fin black marlin are easily distinguished from other billfish as the only marlin with rigid pectoral fins that don’t fold flat against their body. Records show captures of black marlin over 750 kgs and 4.65 meters or 15 feet in length.

Huge Proportions

Many skippers believe they have hooked much larger fish over the years with some reports of fish estimated close to 1000kgs lost during battle. A slate blue back that transitions to a silver/white belly with bright blue stripes when excited, mature fish are less strikingly marked and generally duller in colouration than their juvenile counterparts which are capable of displaying neon blues and purples when “lit up”.

Talk about a baby black – this small marlin was caught in the shallow waters inside Queensland’s Fraser Island.

  Distributed throughout tropical Indian and Pacific oceans found above the thermocline at temperatures from 15-30 degrees, black marlin migrate huge distances often over 8000 kilometres. Australian distribution basically runs from the Tasmanian Coast right up the east coast to the tip of Australia, from Nhulunbuy to Darwin and from Port Hedland to Albany in Western Australia.

Feeding Inshore

Predominantly an oceanic fish black marlin are often found close to land near offshore islands and reefs and juveniles are commonly found close to the mainland where they can be targeted by land based anglers at specific locations where conditions are right.

Gin Clear Waters

One of the most iconic land based marlin fisheries is the tubes at Jervis Bay and in more recent times the beach between Wathumba Creek and Rooneys Point on Fraser Island where anglers can sight cast baby black marlin in gin clear water on the sand flats. The diet of black marlin consists mainly of small tunas, dolphinfish, scad, mackerel, squid, cuttlefish, baitfish and crustaceans which they slash and sometimes spear with their bills in order to catch their prey.

Follow The Moon

Black marlin rarely swim below 30 meters of water and their catchability increases around the full moon and the week afterwards as their prey species move deeper out of the surface layers forcing marlin to forage a much wider area to find food. Like most oceanic apex predators black marlin have rapid growth rates reaching up to 15 kgs in their first year and 50 kgs at 3 years of age. If there is significant sources of food it is believed that a grander (1000 pound, 450 kgs) female could be as little as 10-12 years old.
Jan 12

A sub 20kg black marlin boatside in Hervey Bay.

  Male and female blacks are indistinguishable externally but females attain a much larger size with males rarely growing past 2.7 meters and 200 kgs. Males reach sexual maturity around 140 cms (2 years of age) and females at 230 cms (4-5 years of age).

Spawning Season

  Known spawning areas are restricted to warmer tropical waters around 27-28 degrees Celsius and spawning occurs at specific times in specific locations in the Western Pacific and Indian oceans on the Northwest shelf off Exmouth and the coral sea off the Great Barrier Reef near Cairns during October/November.

Southern Run

marlin 3

Once you hook an inshore baby black one of the first things you can be sure it will do is jump!

It is also believed that there is a breeding ground between Noosa and Seventeen Seventy off Fraser Island due to the amount of mini marlin caught in Hervey Bay. Sometimes the billfish are so small they are nearly smaller than the lures we catch them on and fish in the 1-5 kg bracket are a common catch. Given the phenomenal growth rates black marlin achieve its obvious breeding occurs somewhere off the Fraser Coast.  

40 Million Marlin!

A mature female can produce up to 40 million eggs per spawn usually close to reefs where currents keep the spawn in the area until hatching. The past 5 years Hervey Bay has had large numbers of juvenile blacks moving in to the bay patrolling the flats, ledges and bait grounds inside Fraser Island and are often found in small packs and lone fish in less than a meter of water.

Not Fussy Feeders

Their diet consists of everything from large prawns, whiting, hardiheads, garfish and yellowtail to the many varieties of whitebait sized baitfish more commonly found in the stomach contents of tuna and mackerel.

Another small but feisty fish is landed.

    Little blacks are often seen working the bait balls along side other pelagics and are often hooked by tuna chasers burning slugs back to the boat. For this reason it pays to run a selection of lures from tiny pushers from 100 mm to 250 mm to match the bait in the area. Like tuna Hervey Bays baby blacks can lock on to a particular bait size and feed exclusively on them preferring to slash at swivels that a closer to the profile of bait there feeding on instead of the lure trailing behind it.

Matching The Hatch

MArlin 1

Jono Shales with a sensational sight-cast black marlin from Hervey Bay waters.

Just like tuna if you can’t “match the hatch” then it’s better to move away from that bait school and work the wider area perusing patrolling fish and bigger bait. As mentioned in previous articles I have spent the best part of 20 years trolling inside Fraser Island and the fishery has gone from strength to strength. Every year we see a fresh batch of 5-15 kg fish and a few bigger ones in the 20-35 kg bracket moving in to Platypus Bay.

Off The Beach

Close to Fraser Island you only need a 4wd or a 12 foot tinny to have a crack at them. They aren’t huge fish by black marlin standards and the bay will never be the next Cairns but what we have is a very unique fishery giving so many anglers the chance at a marlin that may never otherwise experience it anywhere else.

Tackle Choices

The tackle we catch them on these days makes them a hell of a lot of fun to catch too weather you use light troll gear, fly or spin sticks and braid. Little blacks put on the best ariel displays being light and energetic they tend to spend more time in the air than under water. Feb 12   Keeping tension on the line at all times is a must as billfish have a knack for throwing the sharpest of hooks especially when airbourne. It is possible to catch little blacks almost all year round inside Fraser Island.

Best Times

That said, the best months are from October to March and that’s when I concentrate on trolling Platypus Bay for blacks. There are plenty of by catch between billfish strikes with Spanish, school and spotted mackerel, bonito, longtails and mack tuna a common capture and queenfish, trevally, cobia, wahoo and kingfish a possibility on any given day.

Track The Water Temp

So with the water temperature rising and black marlin numbers increasing by the day now is the time to get a few mates together and start planning a trip to the Fraser Coast if you have ever wanted to catch a marlin. Local grounds are only an hours run in the sheltered waters of Fraser Island and if the wind is from the East/South-east there is always somewhere out of the wind to catch a marlin.


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