The 4 Ts(Part 2): Transition And Temperature

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Updated: September 21, 2020

Fishing guide Tim O’Reilly continues his pro fishing insights.

Last issue we talked about the dominant factors influencing a day in the life of a fisherman, focusing on the tropics and concentrating on The 4 Ts: time of day, tide, transition of fish and temperature. We covered time of day and tide in #64, so now we’ll look at transition, which is very much effected by tide and temperature.

Moving On

How many times have you marvelled at a sudden change in fishing success? An alarmed ‘Where did they all come from?’ or ‘Where did they all go?’ have both been uttered in equal amounts.

No matter how inexperienced or unprepared an angler may be, if their line is in the water, they have a chance of that magical capture. If the fishing is red hot, make the most of it! Because there is no greater leveller than fishing when it comes to skill versus luck.

Yes, fish do come on and off the bite with predictability. But often, the sudden loss of a bite will simply be fish transitioning to a new location or repositioning themselves adjacent to structure. Fly fisherman and flats fisherman especially have a good understanding of this transition as fish move, graze and generally huddle together in groups of roughly equal size. Patience and stillness are required in understanding just how many fish move through gutters and across flats on their way to and from feeding grounds.

Low Tides

Spend a night stuck on a sand bar of a creek mouth somewhere up in the tropical north and you will learn quickly the transition of marine life in and out with the tide. The noise of scurrying mullet and startled milkfish can be deafening! The only golden rule to marine creatures staying alive in such places is to simply keep on the move. Sit around just a moment too long and they’ll get eaten by something bigger. That goes for baitfish and humans.

One of the most incredible things about fishing in the tropics is the possibility of catching large predatory fish in shallow water, when the tide is high and fish have moved out of the relative comfort of deeper water to patrol areas which were previously too shallow or simply high and dry.

During neap (smaller) tides, try and imagine fish settling into predictable locations and moving around less. Areas such as reef flats, shallow gutters and sandy depressions can fish well for all manner of species, mostly because predatory fish will not have to move away during the low tides. With more consistent water levels, fish will transition less and gather in areas of suitable structure.

Reef fisherman know this only too well and will attempt to coax nearby fish with the use of berley. Fish are inquisitive by nature and will often inspect disturbances or action they feel happening around them. A hot mangrove jack or barramundi bite may have begun with only a couple of fish fighting over a lure. Other fish cannot resist the temptation to see what they are missing out on and the concentration begins.

Big Tides

During larger (spring) tides, imagine fish moving around much more, or at least adjusting to find comfor table holding locations while currents and rivers swirl around them. This lends itself very well to bluewater fisherman and those who are trolling a spread of lures around to pinpoint feeding locations. The northern coastline of Australia is smattered with large bays and river systems which all act like funnels, especially on larger tide streams. Headlands and prominent points concentrate fish looking to travel in and out with the tide.

When a large tide moves over shallow ground, baitfish will attempt to reach sanctuary and feeding grounds up in the shallows, tempting their adversaries to follow them and settle into ambush points. Some of the most enjoyable fishing imaginable can be done on large, difficult-to-fish tides in only a foot or two of water. But you must be willing to follow the sushi train up into these midge- and mosquito-infested locations. Casting shallow divers, weedless plastics, flies and surface presentations for everything from flathead to barramundi is visually spectacular.

Understanding the importance of the tide to marine life is perhaps the most crucial element to success in fishing. Anglers willing to adapt and follow the clues are almost always rewarded over those who simply stick to their game plan no matter what.

This is perhaps the main reason why 10% of fisherman catch 90% of fish.

Temperature (Seasonal Fluctuations & Barometric Pressure)

An often unrecognised and underutilised piece of information which governs fishing success is water temperature. We feel it ourselves and understand to varying degrees what impact it has on our own physiology and surroundings, but usually lack appreciation for what effects it has on fish and their food sources.

Temperature is most often governed by seasonal fluctuations which themselves govern the entire cycle of life in our world’s oceans, shallow seas, estuarine and freshwater environments. It governs feeding behaviours, nutrient cycles, spawning activity, metabolic processes and almost every aspect of the lives of our piscatorial friends. Travelling is the only way for a fish to avoid the surrounding temperature but for most, they must simply adapt to conditions as they present themselves.

Highs…

Water temperature triggers fish into behaving aggressively or passively and successful anglers have a good understanding of the dynamics which govern their target species. Keen anglers adapt their techniques and targets throughout the year to match the species likely to be feeding within 

predictable localities. When out chasing tuna, mackerel and wahoo for example, many gun fisherman look at charts and sea surface temperatures to guess where pelagic activity might be going off.

Providing a blow-by-blow description of which species relish which water temperatures is beyond the scope of this article. The tropics being the tropics however, you can usually be assured the fishing will be at its best in the median range, between 24-30 degrees. The appetite of predatory fish can suffer from sudden temperature and barometric changes, particularly cold snaps.

A thermocline exists in a stratified body of water (such as a lake or ocean), separating warmer surface water from colder deep water. Fish will often move between these two layers to either feed or simply be more comfortable at different times. A sounder is once again the best indication of where life is at its most comfortable and with today’s array of gadgetry at hand, cunning anglers can identify individual species with a clear picture of the structure they are sitting around.

Most sounders give a water temperature reading these days and it pays to keep it in mind when you are next out chasing your target species. Barometric pressure involves the level of air pressure on the water’s surface. It goes on to effect water temperature in a number of ways, but basically it equates to having either a high or low pressure system influencing weather conditions.

And Lows

As a general rule, the more-stable high-pressure systems will exert less pressure on the swim bladders and sensory receptors of fish. They are also responsible for persistent trade winds throughout most of the tropical dry season. On the other hand, an approaching low-pressure system can trigger a short-term feeding spurt, followed by a dormant period while the fish sit idle and often lower in the water column. A nearby low can make for calm conditions in coastal areas, but treacherous and sometimes cyclonic conditions close to the system itself.

The 4 Ts Come Together

It has been a cool day by Cape York standards. We are in late September and a stiff south-easterly has been hurtling across Princess Charlotte Bay all afternoon, pushing a little dirty water up against the coastline and generally making fishing conditions outside the river mouth unpleasant. Dinner is important and the tide is set to start coming in at 4.00pm. The moon is in its first quarter and there is around 2 metres of run. Low tide saw the entire creek almost drain, as many do on the east coast, and only small whiting and mullet could be seen darting around in the shallow gutters.

Using a tiny tinny to navigate out to the mouth, it was clear the first trickle of tide was pushing dirty, warm water over the shallow flats into the creek. Green water which had been allowed to settle in the first deep gutter was eddying past the sand spit where the boat was quietly anchored. Only 20 metres away on the opposite bank, a mangrove line was still high and dry with only a few dead branches and a trapped log sitting in very shallow water.

Schools of large poddy and diamond-scaled mullet could now be seen rippling the surface as they streamed quickly in through the mouth, with the occasional fish seen jumping sporadically in an attempt to clear themselves of an unseen predator. The scene was set as floating shallow-divers were cast long across the mouth.

First a small queenfish and then a blue salmon whacked the twitching lures out in the middle as the tide picked up pace. Then, as the lure neared the bank, a last twitch and pause saw gleaming yellow-orange eyes snoop up from below, narrowly missing that first swipe at the lure. A final twitch right under the rod tip brought the barra undone and the 60cm fish danced over the water’s surface, splashing angler and flapping wildly as it was hauled onto the sand spit.

By now the sun was settling low over the mangrove line opposite and the tide had crept over the log and mangrove branches, placing them in just over a foot of water. Small prawns and herring would occasionally shower in the shallows. As one angler continued casting shallow divers off the sand spit, another tied on a cup-faced popper and flung it long across the stiff breeze towards the opposite bank. After giving the popper a few seconds to settle in just a foot of water, a slow blooping retrieve commenced. A few metres out from the log, just before the drop-off, a hole appeared in the water where the popper once was.

Until darkness, some good sized barra hit surface lures worked slowly and methodically over a steadily deepening, yet basically featureless, piece of water which two hours earlier had been high and dry. These big predators had moved to the mouth of the creek soon after the tide began pushing in, patrolling the edge of a current line where baitfish had to travel past on their way to the shallow, mangrove-lined shore.

The warmer water pushing into the tiny creek with the incoming tide had spurred the fish into action and was perhaps their only feeding time in an otherwise cool and lethargic day. A prime example where tide, time of day, temperature and the transition of fish worked together to produce results.

Next time you are on the water, have a think about The 4 Ts and how they are affecting your results. Don’t let a missing piece of the jigsaw stop you from heading out, but instead try to understand why it is happening as it is. Think through what changes you can make to improve your consistency and plan to mix things up when you need to put a fish on the table.