Scraping the bottom
  |  First Published: November 2006

With so many anglers getting caught up in the soft plastic craze, the effectiveness of deep trolling has been largely overlooked by the current generation of anglers.

As an active lure troller, I often find myself at odds with other anglers I meet on the water these days. For some reason, there seems to be a general perception that trolling relies on dumb luck rather than any sort of skill. Either that, or the majority of today’s anglers have simply forgotten just how effective it is. And believe me, intelligent trolling can be a very productive technique, especially in the hands of those who understand the intricacies of deep trolling.

Deep trolling is the art of keeping your lure running in that highly productive zone, adjacent to, or just slightly above the bottom in deep water. Here you will find all sorts of predatory fish sheltering from the current or waiting in ambush. You will also find that the incidence of ‘less usual’ captures will skyrocket if you can keep your lures scraping the bottom. Fish like snapper, bream, fingermark and jewies will all take a swipe at a lure that runs right past their nose.

This is a far cry from the laid back approach of tossing a few lures out the back and driving the boat along until you stumble onto something. Instead, deep trolling is a calculated approach where anglers target specific features or even individual fish identified on a sounder. It relies on the angler’s knowledge of the running depth of his lures and the effects of winds, currents and even salinity levels. Of course, the implications of tackle choice and set-up will also have a big impact on its effectiveness.

Deep Trolling Rivers

Northern Territory anglers have always been well versed in the art of deep trolling. In the big barra rivers like the Daly, the Mary and the South Alligator, deep trolling is the premier way of pulling big barra off submerged structure. Even though soft plastics have been used for some impressive tournament wins of late, their dominance comes more from their ability to fool large concentrations of fish, rather than by connecting to those big silver-sided beasts we all want to catch.

The classic deep trolling approach in these rivers is to target submerged rock bars or snags. To the well educated eye, most of these features can be identified by the flow-on effect they have on surface currents. However, by taking the time to investigate the river bottom with a quality sounder, it is possible to find some hidden gems that will hold fish.

Reaching these deeper features calls for deep diving lures, but not just any big bibbed lure will do the job. Firstly, the lure needs to be able to reach the required depth while trolling with the current. Longer bodied lures tend to be the popular choice because of their inherent lateral stability in fast moving water. Proven favourites also tend to exhibit fairly brisk, tight actions, with a noticeable degree of body roll.

Diving depth is dictated by water depth. In this case, deep divers capable of nudging the bottom strata in anything between 3-8m may be required. Of course, it also helps if the leading edge of the lure’s bib is wide enough to deflect it away from any potential hang-ups.

This is necessary as rock bars produce a change in water depth. They either mark a drop-off into deeper water, or produce a substantial rise above the surrounding area. Both situations produce an area of quiet water out of the current which fish can shelter in while they wait for a feed. The ideal approach is to have the lure crashing into the bottom on the shallow side and then diving over this edge into the deeper water where the predators are waiting.

Estuary trolling

Deep trolling is under used in most estuaries, but when done correctly it can produce anything from mega flathead to jewies and barra. After investing lots of time deep trolling in our local river mouth, I have found that it is the most effective method – even our mackerel catch has increased now that we target the highly productive bottom layer of water.

The most significant ingredient to estuary trolling success is a concentration of baitfish. Once you find the bait, the predators are never far away. After bait, the next big piece of the puzzle is to find some interesting bottom structure. When you combine the two, the results are almost always impressive. As you pull fish from bait schools sitting in the open water, a rocky bottom increases the chance of a highly desirable reef species getting involved.

Our favourite piece of water is close to the local boat ramp and most boats drive straight over the top of it on the way to greener pastures. We put the lures out almost as soon as the motor starts and frequently pull fish within sight of the ramp. Not surprisingly, our trolling run almost always holds good numbers of bait and there are a couple of isolated little lumps on the bottom that hold fish. It’s not a big area and working it effectively requires repeated short runs, back and forth over the structure that has been carefully marked on the GPS.

Lures need to get down around 3-5m and have the ability to hang in at quite fast trolling speeds to attract mackerel. They also need to be sturdy enough to take regular impacts with rock and coral and survive brutal encounters with estuary cod. While the cod aren’t usually all that big, they hit the lures close to home and don’t have to go far to get you back into the snags. It’s such an unassuming piece of water but we lost a lot of lures in this area before making a move to more serious terminal tackle.

One of the real surprises has been the number of small school mackerel taken in this area. Trolling shallow runners produces some fish, but getting down near the bottom can see the strike rate triple. Small lures that imitate baitfish are required and small minnows have produced solid mackerel and mack tuna for us recently.

Impoundment trolling

Our freshwater impoundments are the original home of deep trolling techniques and targeting native fish sitting close to bottom structure in anything up to 10m is possible with the right lures and techniques. Of course, some native species like bass and introduced species like trout will school up and suspend in open water at certain times of the year, but in most cases, getting your lure down near the bottom is where it’s at.

This is a vastly different scenario to tropical rivers or estuarine areas and generally, lure presentations are much slower and lure actions wider and erratic. Understandably, big old Murray cod won’t be put off by large lures or in-your-face lure presentations but even these are usually made at a pretty sedate pace.

However, even in impoundments it pays to have a plan and be analytical. By selecting a feature or piece of structure and working it over several times you give yourself a much better chance of hooking up. It can also pay to have your lures actually crashing into the snags, as the noise of a lure bumping into the woodwork can sometimes fire the fish up.

dig deep!

I guess the bottom line is that trolling should not be dismissed as a lazy or novice’s way of fishing. Just like casting or flyfishing, there are lots of small things that experienced anglers do to make it more effective and challenging way to fish.

It also pays to remember that many species of fish will inhabit that vital bottom layer of most waterways and there is no better way to target them than by trolling a lure that will spend most of its time running just above the bottom. Deep trolling may not be as trendy as some of the other popular fishing techniques doing the rounds at the moment, but that doesn’t mean you should ignore the possibilities it offers.


Submerged rock bars often give their presence away by creating ripples on an otherwise smooth river surface.


Deep trolling has always been a favourite technique with Northern Territory anglers. This Daly River barra is typical of the fish it produces.


Even young anglers can enjoy success once they master the basics of deep trolling.


Catching flathead on hard bodies means keeping your lures right down on the bottom. This deep diving Merlin lure has racked up an impressive tally for the author.


You never know what will come along on a deep trolled lure. Fish like this giant queenfish will really test your patience and tackle.

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