Thread fin shad kills and their impact on tailwater fisheries

[Phil Lilley]

Thread fin shad kills and their impact on tailwater fisheries

No one knows when it will happen -- the telltale conditions are sometimes sketchy -- but when it happens, it’s the best time to be fishing below dams that are affected.

To what phenomenon am I referring? Shad kills occur in reservoirs such as Beaver, Table Rock, Bull Shoals, Norfork, Greer’s Ferry, and even Grand, Truman and Lake of the Ozarks.

Thread fin shad are specifically named Dorosoma Petenense. The Dorosoma is Greek for "lance body,” referring to the lance-like shape of young shad. The word petenense refers to Lake Peten in the Yucatan, the species type locality. Threadfin shad are usually easily distinguished from gizzard shad by the way the upper jaw does not project beyond the lower jaw. The anal fin usually has 20-25 rays, as opposed to 29-35 rays found in gizzard shad. The upper surface is silver-blue and grades to nearly white on the sides and belly. All fins have a yellow tint except the dorsal. In this species, unlike gizzard shad, the chin and floor of the mouth are speckled with black pigment. Adults are considerably smaller than gizzard shad adults, rarely exceeding six inches in length.

It seems two things need to happen for shad to wash into our tailwaters -- cold temperatures and the shad “getting too close to the fire.” Thread fin shad die naturally in the winter if water temperatures drop below the mid-40s. If temps drop into the upper 30s, more shad die making it more likely shad will appear. The “fire” I allude to is the pipe that leads to the turbines and the tailwater below. Dams in the Ozarks’ region all vary in height and penstock location. Table Rock Dam’s penstocks are at 130 feet deep, so shad have to be near that level to be sucked through

When shad enter that tailwater, they are either dead or dying. Many are chewed up, but some are still kicking, fluttering around like sick minnows. Either way they are easy pickings for trout and other fish to devour.

Shad will come in waves, or they will trickle through the dam a few at a time. Once the eaters get wind of the run and start targeting shad, they gorge themselves, extending their bellies as far as possible… and then some more. It’s a great sight for anglers who like seeing fat fish and the prospect of even bigger fish in the future. Shad runs get our trout well-needed growth boosts.

The trick is fishing at the right time, as in most fishing situations, but it’s not necessarily dependant on the time of day or weather patterns. The perfect time is NOT during a heavy flow of shad because your lure gets lost in the sea of white, and it’s NOT after a heavy flow because the fish are FULL. Since there’s really no way to predict these conditions, the best solution is just to GO fishing.

Helpful hint: If you find yourself in one of those situations, use something other than a white jig or crank bait; try another color and size like a dark-colored jig or a San Juan Worm. You might have better luck with something like that.

When spin fishing from a boat, of course, a white jig is one of the best baits during a shad run. Size depends on how much water is running. I like to “drift” a jig close to the bottom during a run, hovering it in the water column like a drifting, stunned or dead shad. If a lot of water is running, a ¼ oz or 1/8-ounce jig will work. If a minimal amount of water is flowing, use something smaller like 3/32 or 1/16-ounce.

I throw to the side, not upstream or downstream, and let the jig fall, giving it slack, until I feel it’s at the right depth. Keeping the rod tip high, I will slightly lift the rod tip even higher, reeling a bit to “keep track” of the jig’s location. Sometimes in a tailwater, water is flowing in turbulent patterns, moving up and down in the column that will take the jig in a direction that leaves you hanging. You can’t feel the bite unless you have a direct line from rod tip to the lure. Lifting the rod every five to eight seconds keeps you in control of the jig instead of the current leading it.

Jigs can be dressed up with flash-a-bou and tinsel to give them that translucent look of a shad. Combining marabou colors such as gray/white or white with a slither of black will trigger a bite when plain white will not.

Spoons and crank baits will work during shad runs, too, but I have not had real good luck with them. One technique used on the White River is to slow the boat down with a trolling motor, throw a KastMaster or Crocodile white spoon out the back of the boat at a 45-degree angle and let the spoon swing slowly behind the boat, keeping if off the bottom as it swings. A floating rapala can be drifted using a simple drift rig. The bait shouldn’t get hung up, but just make sure it’s a floating bait.

Many fly fishermen don’t like the idea of fishing out of a boat. They’re in love with their waders and like their feet to be planted on solid ground – at least mushy mud, sand or gravel, anyway. But I love fishing out of a boat, especially if it enhances the chance of catching more fish. Believe me, during a shad run, you want to be in a boat.

What you use and how you use it varies with water conditions, just as when spin fishing. The harder the water is running, the more difficult to it is to present a fly or jig effectively. That’s simply because of the turbulants, not the depth or speed of the water. One of the best ways is to use a jig and float. Throwing this rig isn’t fun, though. The float must be big enough to float a 1/32 or 1/16-ounce jig, depending on generation. The jig needs to be down and stay down. If your jig is wandering around beneath your float and a fish picks it up, the strike may go unnoticed because the float won’t do anything. Vary the depth and see where the trout want the jig, deep or shallow. If they’re taking shad off the surface, then set the jig shallow.

Using a sinking line will work, but you have to pay attention to current and turbulants. You’ll have to continually strip the line to keep track of the fly, not fast but slow.

I like to slow the boat down and fish out the back of the boat. That permits me keep better control of my drift. I can control the fly’s depth and will be able to feel a strike better. With this technique it’s best to use shad patterns such as white woolly buggers, bunny shad, clousers, white zonkers or even jigs.

How far down you fish from the dam makes a difference at times. Finding that “happy medium” is where fish haven’t seen the gobs and gobs of shad recently. On the White River, that may be 10 miles downstream. On Taneycomo it could be a mile or two. The White River definitely sees more shad, maybe because their dam isn’t as high as Table Rock’s… not sure. Norfork’s is even lower and, thus, has more shad runs. I’ve experienced fishing these shad runs below Bull Shoals and Norfork. They can be pretty spectacular!

The bottom line is that you have to get out and fish these shad kill events -- and you have to at least try to fish them from a boat. If you don’t, you’re missing something pretty special!

Taneycomo Note: I’ve been asked how far down lake the shad can drift. I’ve seen them as far downstream as Rockaway Beach. How much shad can come through at one time? I’ve seen millions at a time. One winter the shad were coming through so thick that they were washing up in eddies along the banks. I remember when the water dropped, the shoreline looked like it had snowed in some areas below the dam where there were so many piles of shad on the bank, in trees and on rocks. As far as timing, I have seen shad as early as mid-December and as late a mid-June. The June event was a freak occurrence I believe. Most of the time the runs end in April.

White River Note by John Wilson: From what I can tell shad kills occur under conditions that will bring shad close to the intakes or hold them in a section of water that allows them to be pulled through the dams. There are two major seasons when shad will come through the dam at Bull Shoals and Norfork Dam. The lesser known one is during the summer time. These occasions are often referred to as a shad kill. However it is more likely the extreme decompression of going from 300 feet deep to 0 feet within a matter of seconds that does the job. People also often assume that the shad are chopped up by the turbines. Actually the shad come through the generators whole and intact. If it were not for an extreme case of the bends you could not tell that anything was wrong with them.

During the summer the upper levels of the lake stratify. The first 50 feet or so of the lake will warm and the current flows across the upper sections of the lake. A thermocline forms and the shad will travel along the bottom of the thermocline where the water is cooler. Summer means we have high electrical demand thus more generation. The extra generation will actually create a current in the lower sections of the lake. Shad which have searched out the cooler waters of the depths of the lake will be pulled through the intakes. I generally see summer shad kills in August and September when generation is high and the weather is hot.

The most famous shad event happens during January through March. As we have cooler temperatures the surface of the lake begins to cool. Water actually reaches it's highest density at about 40 degrees. Cooler than that and it starts to expand again. This cooler water sinks to the bottom of the lake and brings up the low oxygen water off the bottom. There will be mixing currents of cool descending water and low oxygen water forming pockets within the lake. Shad will attempt to stay in the pockets of good water and these will vary in depth and size depending on weather and conditions.

Often you will see striper fishermen on the lake finding these pockets on their depth finders. They paint those pockets of shad and stripers in the lake with electronics. If there is a fair amount of generation it is a matter of time before those shad find their way through the generators.

It is impossible to predict how much shad will come through the dam at any one time. Usually if you have extreme temperatures either hot or cold combined with a large demand for generation it is a good bet that shad aren't far behind. If you are on the river some of the clues to look for are gulls diving at the dam, fish hitting your white indicator, and of course shad lining the banks or floating in eddies.

The shad kills can be exciting fishing. I've seen 30 inch browns taking shad off the surface like sipping a #22 dry fly. When they get turned on to shad they often throw caution to the wind. Normally selective fish will begin striking everything from white indicators to simple white flies. The guides here on the White River have gotten really plugged in to the shad kills over the last decade. it can often be the best opportunity of landing the fish of a lifetime.

John Wilson is a guide on the White and Norfork Tailwaters.

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