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What does Kariba hold for KITFT 2016?

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In the closing stages of June, Lake Kariba's level stabilised as inflows, primarily from the Zambezi, began declining. The Zambezi River Authority reported a 2cm drop in lake levels between 17-23 June, and this, at a time when the lake was at a lower peak level measured as 480.33m AMSL (2.62m lower than at the same time in 2015), compared to its highest at 482.95m AMSL in January of 2015.

It is predicted that competitors will be faced with similar water levels to 2015. Last year, the lake dropped continuously and fairly rapidly following uncontrolled hydro-electric discharges. This drop left most shallow-water vegetation high and dry, and in its place, exposed denuded areas appeared. Fish went into a state of shock as habitat dwindled, food died off, and traditional breeding areas disappeared. In addition, declines in kapenta would have almost certainly followed the lower inflows and subsequent drop in nutrients and the kapenta's food sources of phytoplankton and zooplankton. Indeed, the changing landscape had anglers scrambling to locate fish in what had become a new, and largely unfamiliar, playing field.

Reasonably good inflows have seen the lake rise to once again flood that exposed shoreline, spurring some re-growth of both habitat and fish. Nutrients released by flooded terrestrial shoreline will be supporting a mini-boom, which will be sustaining fish, and hopefully the tigerfish, too. Though the kapenta fishery should have recovered to some degree, the effect of this will not likely be felt in any major way at this year's KITFT.

Research into the relationship between the kapenta fishery and tigerfish has been ongoing since the lake first filled, and is well documented. In his book, The Fishes of Zimbabwe and their Biology, Professor Brian Marshall writes, "Tigerfish production is directly linked to the kapenta fishery, and the integrity of their spawning areas up rivers. Low water levels affect both these factors". While it was not initially known how tiger would fare in the new lake environment, the introduction of kapenta in 1967/68 was a trigger which saw the tiger evolve to fill a prominent niche in the lake. "The numbers of young tigerfish increased dramatically from about 1970 onwards reaching a peak in 1974, and there was a highly significant relationship between the numbers of tigerfish captured in an experimental fleet of gillnets at Lakeside and the relative abundance of kapenta, based on the catch from Kariba-based boats. At the same time the proportion of tigerfish in the commercial gill-net fishery rose from 6.5% in 1970 to 15.5% in 1974. Its numbers declined after that, probably because the kapenta population decreased".

Professor Marshall says the main factors affecting tigerfish populations are the abundance of kapenta and the effects of drought. He writes, "The lake level fell continuously during a long period of drought, reaching its lowest level in 1998, after which it rose rapidly and remained high following several years of good rains. Tigerfish may have benefitted from an improvement in its breeding grounds and this might explain the good catches in the angling tournaments between 1995 and 2000". With the lake at low levels now, and likely to remain so for the foreseeable future, anglers can expect the tiger fishing to be generally hard.

It is estimated that when stable, Kariba's kapenta fishery will yield between 25 to 30 tons of fish per year. Prof. Marshall explains, "Seasonal variations in abundance are largely determined by the pattern of river flow and nutrient availability during the preceding rainy season". This gives rise to a characteristic pattern with a peak in August following the lake turning in about June/July (mixing of top and bottom layers of water), normally associated with a visible water colour change. This releases trapped nutrients, leading to an increase in the populations of phytoplankton and zooplankton, supporting the kapenta which have bred in the shallows during in the rains, and subsequently move to deeper water as they grow.

With the 2015/16 season effectively being a drought year, and despite some fairly good inflows of water and nutrients, the kapenta production can be expected to be below average. Besides this, any possible peak in kapenta in August of 2016 is not likely to have an immediate effect on the size or abundance of tigerfish by the time October comes around.

The good news is that ongoing anti-poaching operations in the eastern basin--particularly the Gache Gache and Sanyati

Rivers--will mean that to a certain degree, the tiger's spawning areas and the annual run would have been fairly successful over the last couple of years, low water levels notwithstanding. In a previous article on KITFT, we discussed the significance of protecting spawning grounds, especially as it relates to tigerfish populations in the eastern basin. In that article, the ichthyologist Dr. Neil Deacon explained, "In order to sustain any population of fish, at least half of that population must breed at least once". Tiger spawn far up rivers, and it is possible for poachers stringing nets from bank to bank, to catch all the fish migrating up-stream. One could imagine in this scenario that more than 50% of any local population will indeed be wiped out and never get to breed. Neil estimates that just the Gache Gache River alone, if properly protected, has the potential to restock much of the Gache basin and surrounding areas.

So, where will the astute angler be looking come October? Reports from Kariba suggest that there has been little to no regrowth of aquatic plants and weeds wiped out during last year's low water levels, and once the lake drops back to similar levels (likely by October), the landscape will essentially once again be barren. Spinning and trolling are likely to be hard, though are techniques which will account for fish here and there, and may even produce the odd monster. The floating bream cages will be a focus of lure and live bait anglers, and again can be very productive if conditions are right. In the main though, top anglers will be relying heavily on their doba-doba fishing with kapies. Certainly those spots which worked last year are likely to produce again this year. One might speculate that as the kapenta (now growing) migrate to deeper water, tigerfish will be concentrated around them. Assuming this will be the case, we will focus on this method.

Kapenta fishing is an art. Sure, one can chuck a bunch of bait into a spot and hope for the best, but there are better ways to tackle this. Selecting the correct spot is obviously critical and is a multistage process that begins with a little common sense and simple observation. Most top tiger fishermen agree that the techniques they use will catch fish just about anywhere in the lake, but due to the pressure on the eastern basin areas during the tournament, it makes sense to get as far away from the disturbance as possible. Productive areas close to Charara are prone to heavier fishing pressure, leading eventually to their diminished productivity as angler after angler take fish from them. Serious anglers therefor, will brave adverse weather and water conditions to escape the masses, heading to the western extremes of the tournament boundary. Simply, the quieter, less pressured fishing areas are well worth the extra effort and, if you are serious about winning, the extra costs, too.

During Tiger Tournament, the western part of the lake is usually warmer than the eastern part (due to prevailing winds). The difference of a couple of degrees in water temperature makes all the difference to the fish, and in warmer water, they are more active, feed more, and are potentially easier to catch. In good years when vast weed-beds were well established, the water amongst the weed was generally warmer than out in the open lake, but these will be hard to find this year.

Next, look for areas with good visible trees. Kapenta shoal amongst the trees, and as a result tigerfish live and hunt there ... and any area where there are lots of trees has potential. Anything different or unique about a tree line should be noted, such as trees on the edge of bush-cleared areas, or dense trees close to sparser structure, or cleared areas within dense trees as they usually produce more fish than run-of-the-mill tree lines. The actual area selected to tie up to should not be too dense though. Fishing in the ideal depth requires fairly open water, free of underwater obstruction or too many trees close to the boat, as these will inhibit the fighting and landing of fish.

Once a spot has been identified, look for the ideal depth and bottom strata. The shallowest depth would range from 18 to 25 feet (open water), but ideally would be between 40 and 50 feet. For the doba-doba fishing technique used by most anglers, an average depth of 40 feet is ideal. Shallower water (18'-25') is generally only fished away from trees in open water. Ridges, mounds and drop-offs in open water often hold fish, and it is a case of trial and error to locate these, and isolate the productive ones. Some anglers familiar with low water levels of years past have this data stored in GPS coordinates, and will benefit as these spots will produce again now.

Tigerfish prefer a hard strata or lake bed with pebbles or shale-type sand. Muddy bottoms are not good, and by observing the bottomline on the depthsounder (many show the hardness of the bottom), a hard bottom can be identified. Muddy strata obscure the bait when dropped to the lake bed, either engulfing it, or shrouding it in a fine mist of silt, making detection by tigerfish more difficult. Evidence of this can be seen on your bait or terminal tackle, or if you're brave enough, by donning a mask and snorkel and scooting down to grab a handful.

Use a depthsounder and/or a thermometer to establish where the thermocline is, that point at which the warmer layer of top water meets the colder, less-oxygenated bottom layer. Fish will often hold just above this point, but will seldom venture into the colder water below. In the absence of weed this year, the thermocline will be a very important factor to where the fish are holding. Generally expect to be fishing deeper--down to 50 or 60 feet in some cases.

Many areas along the lake have water currents generated by wind patterns. When chumming, both wind direction and water current are taken into account. Tie up to a tree (or anchor if you can), throwing out several handfuls of kapenta. If there are tigerfish in the area, it does not take long for them to home in on the chum. Many believe the more chum, the better. The opposite is true. Too much kapenta overfeeds an area, and the leftovers merely rot, driving the tigerfish away and bringing in the scavengers. An area "killed" in this fashion is unlikely to recover for some days, even weeks, and anglers who over-chum will merely destroy any potential a spot has.

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The experts agree it is better to use too little than too much chum, and a couple of handfuls every half hour or so will suffice. Chum can be whole kapenta, or chopped into small bits so as not to over-feed the fish, keeping them hungry and hunting. When they see a large, whole kapenta, it's a morsel they can't resist. The water currents, if there are any, will easily be seen as the kapenta sinks away to the depths. In shallower areas, the chum is partially scattered on the surface to get better coverage. Often, the water current is moving in the opposite direction to wind currents. Idle "up-stream" of the spot while chumming, aim for your offering to be carried by the elements toward the lake bed in your target area. Even if dropped in the right place, it is accepted that a percentage of the chum will miss the spot, or be stolen by birds and other fish, but keep an eye out for busting fish nearby as they are called in by errant drifting chum.

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Some anglers use a "bomb" or ground bait machine (a cage type apparatus which releases the bait below the surface) to feed deep water. Do not drop it right to the bottom but release it about 20 feet off the bottom, so the kapenta can scatter a bit. At the same time, throw a few handfuls upwind of the tree line to "call" the tiger in. Alternatively, a simpler method (which works better in shallower water), is to pour kapenta into the prop of the outboard while the engine is idling in gear and trimmed up (angling the prop-wash down). This spews the kapenta down and reduces the amount of floating kapenta, which invariably misses the target area, or is picked up by birds. This is done in one rotation upwind of the tree. It is most important to note the wind or current speed and direction, to ensure you always feed upwind of your spot (as already stated, winds on Kariba produce quite significant water currents, often moving bait great distances both above and below the surface).

Once the chum is down, and the boat secured, get the rods in the water. The actual hook-bait should be the biggest, freshest and unsalted prime kapenta you can find. Some teams select these before start of day, and keep them aside, ensuring they are well chilled and fresh. There are many ways to rig your bait, though it is not necessary to pile kapenta onto the hook, and one or two prime kapenta will suffice. When using one, the hook is inserted into the kapenta's eye, turned and fed down through the body to exit out the stomach toward the tail. The hook is then turned, and embedded in the back of the kapenta. The kapenta must lie straight, with very little hook visible, to appear as natural as possible. Alternatively, two can be used by threading the first as described, but the hook is pushed out closer to the tail, and not embedded a second time. Pushing this up close to the eye of the hook, the second kapenta is fed on as described--hooking the point into the tail. Heavy weights are seldom added to one's terminal tackle. Use the smallest split-shot possible, ensuring the bait sinks to the target zone, and gently pitch (do not cast) the bait overboard. If conditions allow, pitch one rod with no split-shot as far out the back of the boat as possible. This bait will be in the chum line and will sink very slowly if a current is present. The bait must be positioned so as to drift into the clearings when cast, and not into the trees. It would be a total waste of time to prepare a spot and then battle to land fish. Losing fish often spooks the shoal and they go off the bite, or leave the area. Keep the kapenta just off the bottom, taking up slack once the line has settled. Experiment with different techniques, retrieving the bait back to the boat, either as a slow, steady retrieve, or as a series of start/ stop retrieves. Experienced doba-doba anglers aver that a greater percentage of strikes come as the bait is slowly sinking--on the drop, so to speak--after being cast. This is especially true as you begin fishing, and before the fish become skittish (possibly due to hooked fish, and missed strikes). It is worth setting your rods at different depths until you are able to determine where the fish are holding. Depending on the thermocline, they may not be right on the bottom and may be suspended in medium depths.

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Doba-doba fishing requires concentration, especially if the water is rough, and the boat is rocking in the waves. Watch your rods the whole time. Sometimes tiger have a very soft bite--not the normal bone-jarring take one usually associates with them. Bites will sometimes be almost impossible to detect while in a rod holder, and it helps to have the rod in your hand at all times. Often, a spot will go "quiet" after a while. If this happens for longer than 15 minutes or so, move; go fish another spot. As you move, cast off from your anchor point and drift your chum line, as you will often get a fish or two. Normally, by resting a spot for a few hours the fish come back, and you can return to the spot later; always keep on the move.

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When you do get into the fish, things can get manic, especially if you're lucky enough to get more than one hook-up. Do not panic. It is not necessary to set the hook with an earth-shattering strike, but rather a firm, sharp tightening of pressure. In many cases, the hook will hold so long as constant pressure is maintained using correct drag settings and the right rod technique. The most important objective in playing the fish, is to get it to the surface and away from any submerged structure. Once you have got him out of the depths, the fish will try and head into any trees close-by. It is imperative that it is stopped from getting anywhere near any form of structure, even if this means tightening the drag to the point where line is likely to break. If the fish gets to the trees, you will lose him. Once up and out in open water, delay landing the fish for as long as possible, tiring him until he has no fight left. If the fish is still frisky and you bring him alongside, that last burst of fight will set him free. Next to losing fish in trees, you will lose the most fish at the boat in this fashion.

In the few practice days prior to the start of the tournament, aim to develop several such spots within easy reach of each other (to limit travel time). Individual spots will often quieten down, and it is important to be able to move to back-up spots, perhaps returning to them all in rotation throughout the day or tournament. You may need enough spots to ensure you have fresh areas for each day, as the pressure on the lake and the fish is sure to make fishing harder.

As of late July, it seemed that the authorities were controlling their water off-take for power generation to 1 000 m/cu compared to 1 600 m/cu for the same period in 2015. Although the lake fell short of the same maximum level for 2015, this reduced usage should help levels come October, offering some enjoyable and competitive fishing for all. Good Luck!
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Title Annotation:Special Feature
Author:Williams, Ant
Publication:African Fisherman
Date:Aug 1, 2016
Words:3160
Previous Article:More than meets the eye.
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