THIS MONTH will see the water temps on the NSW north coast get up to around 21C. These warmer conditions will trigger more aggressive behaviour from many of our summer species.

At the top of the pecking order is the mangrove jack, a species I have chased on the north coast and elsewhere for many years. The fish you are likely to encounter in the north coast rivers are seriously big for juveniles. They usually range between 1kg and 3.5kg with occasional smaller and much larger fish encountered over a season. Regardless of size, jacks fight pound for pound better than any other fish in the Tweed area.

This species has an interesting lifecycle. Spawned on the open ocean currents, the sprats are distributed along the coastal fringes. During the first critical stages of life the fry feed on a pelagic crustaceans until they hit the coast. Here they search out a coastal creek to advance through their juvenile years.

As the jacks mature through their first few years they remain in schools of similar size with a dominant fish taking on the role of ‘head of the school’. This fish, whether male or female, maintains the group’s dominance in a selected feeding location, and resolves disputes among its species. If times become tough, the dominant fish drives smaller fish out of the school. When food is plentiful it allows more fish to join the school, thereby preventing another school from taking over.

When mangrove jacks mature they move into open water, which may be the entrance to a river or a couple of hundred kilometres offshore. What we do know is they’re not likely to re-enter the river or creek from whence they came.

The species is reputed to grow to 1.5m and upwards of 20kg. They are a very powerful fish with a large head and shoulders that help power a big tail. The jaw is large and bony and lined with needle-like teeth, some of which extend outside the mouth. Be very wary when trying to extract a hook as jacks are capable of smashing bones in fingers with a lightning quick bite.

The colour of these fish usually ranges from a rich red to orange with a hint of olive over the back. In juveniles a bright electric blue line can be seen on the cheek. Those fish that live close to the surface can be very dark, almost black.

The mangrove jack is well known as a snag dweller. In the many small creeks along the coast these fish seek just about any cover, as long as there’s a good food source close by and some deep water they can retreat to from predators. In one local creek there’s a very deep hole that drops to 8m or so. The main flow enters the hole over a shallow sand bar that has less than 30cm of water over it. When the flooding tide pushes water over the edge of the bar the jacks patrol the edges, waiting for baitfish. Some years ago a big dead tree fell on this drop off. Within days most of the big fish launched their raids from this point.

In larger systems the jacks prefer dead trees and undercut banks giving way to rock walls, bridges, rock bars, car bodies and any other artificial items that end up in the system. The same principles apply everywhere – where there is a good supply of food and deep cover, jacks will take up residence. The better the current flow and the more oxygenated the water, the more jacks like it.

The mangrove jack’s huge eyes allow it to hunt at night. During the day these fish usually hole up in a cave or on the shaded side of structure, so keep this in mind when you’re casting to a location.

Dirty water is often favoured, and it’s often a case of the dirtier the better. This was certainly true one afternoon when I was fishing a huge exposed rock bar in the mouth of the Pine River at Weipa. The tide had just begun to flood and I had found a bit of a gutter less than a metre deep that was swirling around a point. Directly in front of me, the water was only 30cm deep. I put my fly rod down so I could tighten my sandals, and within seconds the fly was ripped from the rod tip and a big jack was landed after a furious close-quarters battle. I caught a few more fish close in before the barra arrived. It just goes to show how important cover is, no matter what form it takes, for predators to hunt in.

On some of our bigger bridges the main support columns are supported below the waterline pads by multiple columns. The fish love to sit high in the water directly under the concrete.

One good method is to drift a lightly-weighted livebait in under the pylons and wait. Hold on to your outfit because the strike is fast and furious. I’ve seen some keen anglers with multiple outfits set up with livebaits on outfits set in freespool with the ratchet on. With tackle more suited to offshore fishing, these guys are willing to strip 20m or so of cheap 24kg line off their reels each time they hook up just to have a crack at some quality fish. The key to this style of fishing is to remember to set the ratchet and freespool mechanism or to hold onto the outfit at all times.

Trolling lures that will get in close to where these fish are holding is critical. A large lure with barbless hooks, such as a gold Bomber, is best. I recommend barbless hooks on all trolling lures. If you hook up and get busted off, the fish will often discard the lure and you can retrieve it within a matter of minutes.

Casting Prawnstars or drifting them in under the bridges is a deadly method. These lures come with a range of weights that allow you to vary the depth you’re fishing. They also allow a longer period in the strike zone. The slowing tide is ideal for using Prawnstars, and the action of a skipping prawn is easy to impart.

Rocky areas contain better numbers of jacks than any other, particularly where deep water flows quickly right up against the structure. I try to fish locations where discoloured water is apparent on both tides. If this isn’t the case and you have found fish in a clear water location, night-time or late afternoon and mornings are the most productive times. Whitewater washes are an exception to the rule; they provide ideal conditions because of the foam and aeration bubbles.

Prominent points and groynes are likely locations, particularly if there is plenty of current swirling over a bottom covered in rock or rubble. The rule for fishing these locations is simple: with plenty of light the fish will be deep in the water column, and as the light fades the fish will become more adventurous, venturing further from their dark homes.

Livebaits and cut bait can be fished in a number of ways. A traditional running rig fished to the upcurrent side or the downcurrent side of a rock bar will eventually draw fish. Baitfishing close in along a rock wall, groyne, or an area with eddying water, can be successful, but I prefer to pitch a bait from an anchored boat to an upcurrent point close to the rocks and let line out as it drifts downcurrent. This can be done using a lightly-weighted bait or by using a small torpedo float and an adjustable float stopper to allow for a depth change. A dead bait is just as effective as is a cut bait and far more humane. The take is similar to a bream tap, and your reflexes need to be quick and as brutal as possible for those first few seconds are when you’re most likely to lose the fish in the snags and rocks.

Trolling is very effective on the rock bars and walls. Look for lures able to handle being bashed into rocks, because that’s where the lures need to be. Trolling along a rock wall in 6m of water means you’ll need to use a lure that will occasionally hit the bottom while you’re lifting and lowering the rod to keep it in the strike zone. If you achieve this goal when running along a wall, you can mark the braid with a felt pen to ensure your lures will troll in the same depth on the next run. I occasionally run a lure in mid-water as the light fades. Whatever it takes, it’s worth trying something to induce a strike. A hook up generally fires the school up, so it’s then time to work quickly over the same ground.

Casting large single-tail or paddle-tail shads is also very effective. Keep the lure tight to the wall to maximise the time it spends in the desired area. I’ve caught jacks on plastics from 1” to 6” long, generally as a bycatch while chasing bream on small plastics through winter.

When the water hots up during summer, plastics about 4” are ideal. Just throw the plastic into tight cover for a chance to mix it with a good fish. Follow the contours of the bottom and fish as you would for bream.

Fallen trees, jetties, deep rocky points, shallow reefs and anything else that fits into a shallower presentation is worth a try. Shallow water fishing is more visual and is better suited to anglers who love casting lures. I save these locations for evening fishing sessions when there is a bit of moon. The lead-up to the full moon is especially good.

When the trevally schools invade the northern rivers the competition for food hots up and so does the action. Surface lures can be dynamite on jacks, with my favourites being poppers and fizzers. You’ll get fewer hook-ups on fizzers if you don’t know how best to fish them, but they are great fun to fish. They imitate a prawn better than any other surface lure. At night you can throw surface lures over the most evil country and they look just like a prawn, and nothing gets a predator more excited than a prawn skipping along the surface.

Take barra, for example. Fishing drains where barra are feeding on prawns is very exciting but there comes a point when they will start to shut down. I have switched a bite back on by using a fizzer. If you can resist striking your hook-up rate will be much better, but nine times out of ten you’ll probably have a crack at striking. That’s the challenge of this lure!

Ideally, you should make your fizzer spit water like a prawn does when it’s escaping across the surface. Less is more with these lures when trying to achieve a good presentation.

Shallow runners are hard-bodied bibbed lures that are well worth using. It’s not simply a case of throwing it out and winding it in, however. My favourites are the suspending baits. Using a short rip of the tip will see this lure jump from side to side with a slight pause in between. A small baitfish that has lost its way or has already been belted by a predator will act this way, and is easy pickings for any good fish. You could also try a sinking lure using this style of retrieve, as dying baitfish often sink.

Soft plastics rigged weedless on a big wide gape hook are incredibly lifelike, and will pull fish where many lures have passed before. They run true with the right size hook and are as subtle a presentation as you can get. The paddle-tail plastic with a slender body is perfect for a simple cast and retrieve. For a slightly more aggressive approach, a dagger or pointed-style tail can be presented the same way as you would a crankbait, except that this lure’s action is a little more subtle and slow.

Mangrove jacks are one of those fish that make poor tackle or badly-maintained tackle look very bad. Their style of fight is fast and furious. There is no need for great lengths of line on reels or sensitive tips on rods, but rather good gear that can handle their explosive nature. You must be able to put the wood on a jack straight away regardless of size. A small one in summer can make you look pretty ordinary.

A jack’s jaw is hard bone with a soft area between it and the skull. Hooks need to be strong and sharp, and if you secure a good hook-up in this area it won’t let go. There is no place for cheap hooks here.

Most of the mid-price gear these days is quite capable, particularly middle-of-the-range reels and rods. Get good advice from tackle store staff who know what they’re talking about. Compare their advice with other stores and you’ll soon find your feet.

Above all, any gear you choose needs to be comfortable in your hands and well balanced. Remember that you’re going to have the outfit in your hands for the day.

Terminals and traces need to be of good quality. Forget the wire and super heavy mono; 8-24kg monofilament leader will cover every aspect of jack fishing, depending on the terrain you’re fishing and technique you employ.

The leader materials these days are great. I use traces that are resilient to the hard scuffs from the terrain the jacks prefer.

As a main line for this style of fishing, braided lines are best. On threadline reels I have always used braided lines of 6-10kg, and with overhead reels I up the ante with 10-15kg braid for the main line.

Regulations on bag and size limits for NSW are five per person and there’s a minimum length of 35cm (don’t forget the mandatory NSW fishing permit).

To me these fish are pretty special. They’re at the pointy end of the estuary fishery, and therefore should be treated with care. If you release them they will be there when you come next time.