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We are lucky enough to have two of the Lutjanus family of fish endemic to Central Queensland, Fingermark (L.johnii) and Mangrove Jack (L.argentimaculatus).

This article features on fishing for Mangrove Jack in estuary and inshore tidal fisheries in central Queensland.

Mangrove Jack (L.argentimaculatus) are very solid fish that have powerful teeth, hence Mangrove Jack are often referred to as dogs or dog fish. They have big powerful tails and are very much the close combat specialists. The colour of Mangrove Jack varies according to their habitat so they present in a range of colours from silvery red to sold red and dark olive brown tones.

They are found all year round throughout the northern half of Australia and are a highly sought-after target species on both fly and lure.

In the colder months Mangrove Jack reduce their metabolic rate and reduce their food intake but of course you can still target them in some of the locations described below particularly those where the energy they get from feeding intakeis higher than the effort they have to use up. Then as the water starts to warm up in late spring their metabolic rate increases and their food intake increases.

Both juvenile and maturing fish are essentially estuary fish but bigger fish do move to rocky coastal shores and relatively close reef areas.

Mangrove Jack also venture up above tidal flows into brackish rivers and creeks for extended periods of time.

An average size 40 cm Mangrove Jack is a powerhouse and once hooked its first intention will be to get deep into or under cover … they fight well above their size.

Mangrove jack are both scroungers and predators in that on the one hand they will foraging around the bottom and in and around structure for tucker yet on the other hand they will take advantage of structure and wait for food to come to them.

Interestingly the best structure is generally very much the domain of the biggest Mangrove Jack.

HABITATS

Mangrove Jack frequent a wide range of natural habitats including mangrove lined shore lines in both open estuary waters such as harbor and bay shorelines, rivers and creeks, tidal run offs from gutters, rivers and creeks, snags and rock bars.
Other locations that Mangrove Jack frequent are man-made structure such as bridge, jetty and mooring structures and rock walls.

For any of these types of habitats that get uncomfortably shallow for Mangrove Jack at lower tides keep in mind that they will be more inclined to hold fish if there is deeper water close by that they can retreat to.

Those deeper retreats are important habitats for Mangrove Jack also. Even better if those retreats hold their own structure such as rock bars or sunken timber that stays covered on low tide … a good way to locate those areas is to do a lot of scouting about on low tide and to lock appropriate marks in on your GPS/sounder.

Around Gladstone popular areas to target Mangrove Jacks are the gutters and structure of our coastal rivers including the Calliope River, South Trees Inlet and the Boyne River, the mangrove lined back waters of the harbor and structure in local estuary bays like Colosseum and 7 mile and moving a little further away the Narrows and Turkey Beach.

FOOD SOURCES

Mangrove Jack chase the same sort of food items as Fingermark, Grunter and Flathead including; prawns and shrimp, small fish, crabs, mollusks such as rock oysters and worms so it’s not surprising that fly and lure representations of those naturals are a good choice when targeting Mangrove Jack. That is not the end of the story for mangrove jack they are very territorial and will willingly take other non-natural looking offerings that ‘inadvertently’ draw their attention.

As it turns out Mangrove Jack are cathemeral feeders which means, that because their eyes have evolved to allow them to hunt in the dark and other times of low light and consequently when they feed is determined by other factors other than night or day. Those factors are what we call trigger events.

Mangrove Jack understand those trigger event ever so well as it’s entrenched in their DNA.

For us, the more of those triggers that we can understand and line up the better our fishing outcomes will be. When less triggers line up it’s reasonable to expect that Mangrove Jack don’t eat so well and when there are no triggers the Mangrove Jack just don’t feed and may go hungry. Sure, they may scrounge up something to eat but without the triggers being present and creating what Mangrove Jack see as bite windows Mangrove Jack won’t congregate and our chances of finding numbers of feeding fish in predictable places gets harder.

As anglers what we have to do to get the most out of our fishing time is to recognize what the triggers for bite windows are and what causes the triggers to be in different places at different times so that we can take advantage of the accumulation of those triggers, just as the Mangrove Jack do.

I have set out below triggers which can have a profound influence on the occurrence of bite windows and consequently the success or failure of a barra fishing outing.

As I understand it the three main trigger event that instigate bite windows for Mangrove Jack are tides, barometric pressure and low light. I have described their influences below:

Generally, Mangrove Jack are most active on the last of the rising tide and the first of the falling tide.

As you work through this post you will realize that a good strategy, particularly if you have a high tide around dawn or dusk, is to fish sessions that include the last two hours of the rising tide and the first two hours of the falling tide.

FEEDING CYCLE

• As the tide is rising small fish, shrimp and prawns become vulnerable as they move into the mangroves and other structure where they can feed and feel relatively safe. In the early part of rising tides it’s still too shallow for the Mangrove Jack to follow those small fish, shrimp and prawns into the mangroves but they do move closer to the mangroves so they can pick of small fish and shrimp as they run the gauntlet to get into the cover of the mangrove roots to feed. Flies presented on intermediate lines as well as soft plastics and hard bodied lures work well at this stage of the tide.
• In the latter part of the rising tide when the tide inundates deeper into the mangroves Mangrove Jack and other predators such as Fingermark, Grunter and Flathead will also move into the mangroves proper to ramp up their feeding. As the water in the mangroves gets deeper the predators do the same and particularly on the bigger tides that pretty well take all of those predators out of range./li>
• As the tide starts to fall below a comfortable depth for Mangrove Jack and those other predators they progressively move out of the mangroves and station themselves close to the edge picking of small fish, shrimp and prawns as they run out of water and run gauntlet to get back to deeper water. This is a good time to move back to flies presented on intermediate lines, soft plastics and hard bodied lures.
• Once the escaping flush declines, and the run of small fish, shrimp and prawns spreads out in deeper water, the Fingermark and other predators retreat to mud flats or holes and other deeper structure close to where they were feeding and they scrounge around those areas until the next high tide approaches and the feeding cycle starts again in earnest. This is often the same area where Fingermark, Jacks, Flathead and Grunter may be scrounging for a feed. That gives at least four species that can be targeted at this stage and they can all be targeted on similar set ups. My preference is flies on fast sink lines or on the dark side weighted vibes, appropriately weighted soft plastics and diving hard bodied lures.

Mangrove Jack thrive in the warmer weather, especially when there is an afternoon storm looming. That dramatic fall in barometric pressure that occurs when a storm is imminent triggers a dramatic bite window for Mangrove Jack and Fingermark often putting them into overdrive feeding up pre-storm. Once the anticipated barometric pressure does drop and storm becomes active, they turn off just as quickly as they started feeding.

THE GEAR

 
For fly fishing my preferred gear is a #10 weight fly outfit with a straight rod length leader of 30lb Maxima Ultragreen monofiliment. Depending on water depth I generally work between an intermediate line at the shallow end of the tide and a fast sink line for the deeper end and the ebb of the tide.

Flies presented on solid hooks in the #2/0 to #4/0 range representations of prawns and small bait fish are great flies for Mangrove Jack, Fingermark and other scroungers. Those flies end to fall into two distinct types. Heavier flies with enough weight to get them down to where fingermark are feeding during times of deeper water and lighter flies that have some sort of structure guard or flies that swim hook point up that can be fished as deep as possible into the mangroves and other structure. In both cases if your not getting snagged occasionally your not casting deep enough into structure.

Focus on repeatability twitching the fly and then letting it sit so your in the zone as long as possible. A lot of takes come as the fly settles on the pause and then the only problem you have is to get the fish out to clear water and into the net ... often easier said than done.

You'll find plenty of fly options to fit the bill in these selections:
My big fish fly box – temperate & tropical destinations.
My #8 weight fly box - east coast estuary & coastal waters
My #8 weight Tropical Pacific sand flats flies
 
On the dark side hard bodies will work but I hardly ever tie them on when fishing for Mangrove Jack or Fingermark as I think that the options below give you more bang for your bucks.

There are plenty of soft plastics that imitate small fish, prawns and shrimp and for rivers and estuaries those in the 3" to 4" range that have plenty of action can also be scented up to provide a great option for feeding fish. They can also be rigged on appropriately weighted hooks when fishing deeper water or on weedless hooks when your fishing around shallow structure.

When fishing deeper water over gravel my preferred option is vibes up to 30 grams and 8cm long. You need to get those down and hoping along the bottom and where necessary you may even need to rig them on a snake loch lead head to keep you in the zone when you fighting wind and tidal currents.

STEALTH

Keep in mind that mangrove jack and fingermark are easily spooked so you have to be stealthy in your movements and casts.

• So when you approach an area you going to fish do it slowly and if available quietly under the power of your electric motor and take advantage of any cover that’s available. Don’t cast a long shadow over or motor over over the water your going to fish. Longer casts are important and cast to the side of any fish your targeting.
• If your using an anchor deploy and retrieve slowly so that there is no bumps or chain noises that will spoke fish.

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