Understanding Shad Means Understanding Bass
By Steve Price
Itís ironic that the one species of fish that all largemouth bass anglers should worship is the one most know almost nothing about, the threadfin shad.
Of all the elements that factor into the equations of bass location and behavior, the presence of this small baitfish nearly always plays a leading role. The threadfin shad (Dorosoma petenense) has been described as the "perfect" forage fish, and indeed, it comes close. It's only real limitation is it's intolerance to cold water, but even so, many state game and fish departments deem the threadfin so important to a lakeís ecosystem they often stock them in spite of winter die-off problems.
Other characteristics more than make up for the threadfinís otherwise limited range. It likes calm, shallow water. Itís prolific but it does not outgrow its place in the food chain, as it rarely exceeds three inches in length. Equally important, threadfin shad do not seriously compete for space with other species.
Gizzard or Threadfin?
Not only do a lot of anglers misjudge the threadfinís importance, many cannot positively identify a threadfin shad on sight. Thatís understandable, since it has a lookalike cousin, the gizzard shad (Dorosoma cepedianum), that for a short time looks similar and has many of the same characteristics.
Gizzard shad also occupy an important niche on the food chain, but they have one characteristic that forever sets them apart from threadfins: they grow much larger, up to 16 or 18 inches, and thus may outgrow the bass that feed on them. In fact, one reason striped bass were originally stocked in some reservoirs was to control these larger gizzard shad.
Basically, both threadfin and gizzard shad are silvery-white in color and have distinctly forked tails. The threadfinís tail, however, has just a shade of yellow, while the gizzard shadís tail does not. Closer examination will also show that the lower jaw of the threadfin shad projects beyond the tip of the snout, but a gizzard shad has a more blunt nose and the jaw does not protrude beyond the nose. Both species often have a distinct black dot on the shoulder, behind the gills.
Migrating for Micro-Meals
Threadfin shad live primarily on microscopic plant and animal life, phytoplankton and zooplankton, which is why they are often found around rock riprap, bridge and dock pilings, and areas with gentle current where algae grows or is washed into the system. They are more surface-oriented than gizzard shad, and frequently move in huge schools just under the surface, sometimes migrating for miles each day.
These movements, when located or tracked by anglers, can open the door to some truly spectacular fishing action, because the schools of shad are nearly always followed by schools of bass. Many bass fishermen have experienced schooling action in which bass trap the schools of shad against the surface and suddenly begin tearing into them like sharks. Typically, such action lasts only long enough for an angler to make one or two casts before the school submerges and disappears.
Track Those Shad
There are, however, ways to actually follow schools of migrating shad and catch bass steadily until the baitfish finally disperse; or to predict where and when these migrating schools will show up and be there waiting for them. As long ago as 1970, no less a fishing authority than Bill Dance experienced just such a migration pattern on Sam Rayburn. Dance followed the school for several hours each day for 10 consecutive days; and guides on Toledo Bend as well as Greers Ferry and Table Rock Lakes in Arkansas and Missouri have experienced the same thing as they tracked the shad in their daily migrations.
It is now well-established that massive concentrations of threadfin shad seek shoreline cover each night. This cover can take the form of grass and moss beds, logjams, or even standing timber and brushpiles if thatís all thatís available. This cover provides them with some semblance of protection from predators like largemouth bass.
Early in the morning, generally shortly after dawn, the threadfin leave this shallow water cover for deeper haunts where they may disperse slightly for the balance of the midday period and early afternoon hours. The threadfin then re-group and return to the shallow water cover late in the afternoon, frequently by reversing the same exit route they used that morning.
Why is bass fishing good in shallow water early and late each day? The answer is because the shad have already moved in for the night, or have not left for the day. Why does the morning action frequently end just after the sun peeks over the trees? Because the shad have left and the bass are following, but not necessarily feeding on them.
Dance Keeps Track
Consider Danceís experience on Rayburn: "In September, 1970, I was competing in the Texas National B.A.S.S. tournament on Sam Rayburn," recalls Dance, "practicing in a small creek that contained open water near its mouth and heavy standing timber in the back. About 7 a.m. I heard a lot of feeding activity in the timber, and when I eased my boat into position, I was able to catch several bass before they disappeared.
"As I was sitting there, the feeding started again about a hundred yards away. The school of bass was heading out of the creek toward the main lake, and before they went back down, I caught three or four more."
"That morning I followed those bass for an hour and a half as they traveled from the creek all the way out into the main lake and into the timber of the Black Forest where they finally disappeared. I followed those bass every morning like that for 10 straight days. The shad were migrating from the Black Forest to that creek at night, then moving to the main lake again early each morning, and the bass were following them."
Professional fishing guides who have been able to follow shad migrations like Dance describes, believe bass are more likely to attack the baitfish when the shad school becomes more compressed, packed tightly together. Or, when the school is forced closer to the surface, such as when the shad move over an obstacle like a hump, roadbed, or submerged fenceline. That way, escape options are more limited for the shad and the bass certainly do not have to chase them as far.
Even more exciting, perhaps, is the knowledge or fact that if these "ambush points" can be identified, thereís a good chance bass will attack them there again that evening when the threadfin migrate back through on their way back to the shallows.
What do you look for in a shad migration route? Itís difficult to pinpoint anything precisely because much depends on the characteristics of the lake. Perhaps the best thing to do is immediately check any areas where you see and experience surface activity between bass and shad with a depthfinder to determine whatís on the bottom. The shad may be following a ditch, small creek channel, or some other specific terrain feature you may then be able to backtrack to their nightly hideout.
When do shad migrations take place? Again, the answer depends on the lake as well as on their temperature driven spawning cycle. Threadfin shad spawn in shallow water coves from late April into July, depending on the surface water temperature. The optimum spawning water temperature is 68 degrees.
Threadfin shad grow rapidly - life expectancy is two to three years - and the migrations from shallow cover to open water tend to occur from late spring throughout the summer and well into autumn. Again, much depends on the lake; the amount and location of phytoplankton and zooplankton, and water temperature. Threadfin shad cannot tolerate cold temperatures and actually begin dying (winter kill) when the water reaches approximately 45 degrees.
Find the Current
Threadfin shad have another habit that may help observant fishermen catch bass. They appear to be attracted to slight current during times of high water. A recent national B.A.S.S. tournament was won on Table Rock Lake in Arkansas by an angler (a guide on Lake Ouachita in Arkansas) who found huge schools of shad in the back of a small cove fed by two little creeks.
The angler had never fished Table Rock prior to the tournament but saw water and shad conditions similar to those he frequently fished on Ouachita. That small cove produced five limits of bass in two days and at least one more limit (the winnerís) the final day. This on a lake in which more than 90 contestants blanked the first day!
Obviously, there is much more to be learned scientifically about threadfin shad and their direct relationship to bass. And just as obviously, every bass fisherman owes it to himself to increase his own knowledge of this tiny fish. The popular adage, "Find the bait and youíll find the bass," is certainly true in the case of the threadfin shad.