Mangrove Jacks: The Biography

Jacks Dan

Mangroves Jacks are amazing fish and it is little wonder why they are held with such high esteem amongst anglers.

Possessing supreme power, strength, and the ability to destroy gear in braid burning runs of red fury, the mangrove jack is a challenging fish to capture which is what makes it so special and unique, as Dan Kaggelis reports.

Offshore reef jacks are commonly taken on both plastics and bait often fished above schools of other red fish like saddle tail snapper or red emperor. (Mark Gwynne Image)
Jacks encountered in the rivers in South East QLD are typically larger due to their lack of offshore migratory tendencies. When they push over 60cm they are real trophies. (Matt Stott Image)

Typical north QLD jack.

They are great fighting, look fantastic and top eating. 

Whilst its reputation is well known all around the Australia, many anglers are unaware of just how unique jacks are in terms of their behaviour and habits and how these vary depending on the location they are found.

Firstly, most anglers identify jacks as being a more tropical northern species much like the barramundi. This is far from the truth and jacks can be found in good numbers right down to the central coast of NSW and just north of Geraldton in the West.

In fact the South Eastern Corner of QLD and NSW populations of jacks are phenomena as they can behave very differently to those that live in the north. One of the biggest differences is the size of fish encountered in river systems and canals.

In north Queensland most jacks encountered typically never grow much larger than the 50cm mark because when they get to this size they will leave the creeks and rivers and begin their journey out to the inshore reefs, wrecks and shoals to spawn.

Time to go to sea

These oceans going fish can grow easily upwards of 10kg and are quite commonly encountered in large schools. Their southern cousins however are quite content to maintain their creek and river system living arrangements even at an adult age with fish up to 60 and even 70cm not uncommon especially in the bigger systems such as the Nerang River near the Gold Coast.

Jacks this size landed on creek gear are simple outstanding to catch and are a real trophy fish.

There are many reasons as to why they may stay in these systems and this includes the lack of large predators such as barramundi or crocodiles which are encountered in the north. Other reasons include the abundance of bait and structure in particular man made structure which are prevalent in these areas.

These southern systems are full of canals and rock walls and ledges and deep water which is perfect for big jacks to thrive in.

The final reason is the lack of reef and shoals in close in these areas. Unlike the north which has an abundance of inshore grounds the southern areas have little in the way of joinable reef systems which tap the inshore areas to deeper offshore areas, restricting movements and opportunities.

Eye to eye with jack

As a free diver spearing many of the southern waters, jacks were a common sight along many of the headlands and inshore reefs but are not a common capture when compared to species such as snapper on the offshore areas. 
What many don’t realise is that jacks just don’t make their way straight out to the outer reef.

They tend to move from inshore shoal or island to inshore shoal or island until they eventually make their way wider and wider.

This is why it is common to see mid-sized jacks around inshore islands and headlands and the further you head out the larger they are encountered.

Island jacks are commonly around that 50 to 60cm mark whilst reef jacks are more commonly encountered around the 70 upwards mark as these fish have developed during this offshore journey. There is some belief that these larger fish do move back to the creeks to spawn but in my opinion they are much like saddle tail snapper and red emperor and move onto the closer shoals in summer but not back into actual creek systems.

A highly sought after target

ard body lures which can be suspended and twitched through structure are must for chasing jacks.

Hard body lures which can be suspended and twitched through structure are must for chasing jacks.

Targeting jacks in the southern areas is becoming a very popular past time and for many anglers it has become an addiction and its not hard to understand why with such huge fish on offer in creeks and rivers.

They are commonly taken on lures around many of the canal estates especially when working pontoons which provide plenty of bait holding structure. Some tips for chasing jacks in these areas.

First clean water is best and if the water is murky the fishing will be tough. Try and fish canals which are dead ends as these create the perfect eddies for bait to school and get comfortable.

Large concentrations of bait will always attract fish. Try and work your lures along the face of the pontoons as this will keep your lure in the strike zone for much longer. Having an electric motor is a must for this and being able to position the boat to maximise your casting is essential.

Cast to the shade

If you can see shade then cast at it. Jacks love a change in light to ambush bait. Retrieve is vital and I believe the best retrieve when working pontoons is a fast one.


Paddle tail plastics are perfectly suited for jacks when snag bashing in the creeks.

Canal jacks require a little more encouragement and you need to play on the instinct bite a lot more and a fast retrieve is ideal. The final tip is to cast a little longer and land your lure on the pontoon. This way you can drag it into the water right on the edge which is often where the jacks are found lurking.

When chasing jacks with bait, larger structures like bridges are excellent especially in southern waters. Well lit bridges attract big schools of bait and big jacks and some down the Gold Coast are well known spots for trophy jacks. Some prefer using live baits but in my opinion fresh dead is a better option.

Moving a little further north and you begin to see the change in size diminish with the areas around 1770 being the line where the jacks begin to adopt the migratory approach to life. Creek jacks tend to be smaller but in much more abundance and are commonly taken by those casting both hard body lures and soft plastics deep into snags.

Jack fishing in this sense is very different to chasing barramundi as they prefer snags which are covered at all tides. Casting deep into the timber is an absolute must so weedless rigs or suspending hard bodies which can be twitched through timber is a must.

Rule number 1, be prepared!


The big choppers of a jack are both frightening and impressive and are very often the last thing a baitfish or prawn sees.

Being prepared for that vicious and violent attack is also a must and having a top notch leader is absolutely essential for these fish. I use nothing but Sunline FC Rock or FC100 when chasing these fish because it is super strong and tough and can withstand plenty of punishment when those big fish drag you through the timber.

Anything less and you are simply donating tackle and learning new material for the big one that got away story. When chasing jacks on lure it is best to target them on the bottom of the tide as the less water around the snags means your lure is closer to the fish.

Jacks always feed the hardest on the first run in of the tide which often means the bite doesn’t last very long.

However, when they come on, they come on thick and fast and the action is brutally awesome. 
When moving offshore for the mangrove jack there are many different theories on how to target them successfully.

I attribute much of my knowledge about offshore jacks from what I have observed diving in Queensland, Western Australia and surprisingly enough in Oman in the Middle East where they are also commonly captured. They are also prevalent right through Asia and even the US where they are called Mangrove Snapper.

In all occasions I have found fish in schools often holding in shoaly country commonly associate with saddle tail snapper or red emperor country. I have also caught them around wrecks and isolated structure.

In terms of catching experience I have rarely encountered them in waters deeper than 60metres and mostly at night. They can be tricky fish to target and many anglers I know will fish for them purposely above schools of reds by suspending baits half way in the water column similar to when chasing mackerel.

They will commonly grab baits and swim up with them making the fight quite unusual but when you put the hooks into them they go like the clappers.

The final word

Sometimes reef jacks are commonly mistaken for red bass in offshore areas so be wary as the red bass is a no take species due to implications with ciguatera. It is also worth mentioning that these larger fish are very old with some reef jacks over 80cm being well beyond the 20 years of age mark. These larger fish are not the best chewing so only take what you need.



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