Stalking the Elusive Shoal Bass

Guest Author: Amy Cottrell

Editor: Solomon David

The sun began creeping up over the tree tops and casting morning shadows and specks of daylight on the water surface, slowly lighting up more and more of the heavily vegetated creek bank. We paddled the quiet corridor, antenna rotating side to side in front of me as we eagerly awaited the all too familiar frequency signal.

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I can’t think of any other time in life when one yearns to pick up a constant beeping sound other than when searching for a tagged animal of interest. Today, and every day in front of and behind me for 18 months – two complete spawning seasons – I am out on the creek, paddling, running, dragging, swerving, searching for radio-tagged shoal bass. We come around a sharp bend with bedrock outcroppings and deep, sleepy water on one side and a low sloping, sandy bank on the other, the future route of our paddle gradually being revealed to us. These sharp bends suddenly place us in a new direction, and I immediately start assuming I know where we will find the next fish. Another nice bedrock and boulder patch on the right with fierce flows whipping by looks like a classic shoal bass hang out.

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I know we will find #591 here – she’s been here all spring… and winter… and fall. But as we near the ever-familiar patch, with two large laydowns jammed against the upper portion, we continue to hear static. I double check her frequency… still nothing. Strange. Did this fish die? Was its fate sealed by a resident raptor? Was it caught by an angler? The last possibility was unlikely – this portion of the creek was rarely frequented by anglers, as we have never seen anyone in this upper section. Too annoying to traverse for most. So intriguing! Where was #591? As we continued downstream, I anxiously awaited her frequency, hoping we would find her and excited for what her new location would reveal to us.

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Black bass native to the southeastern US have recently hit a major wave of visibility and adoration, with biologists and anglers alike along for the ride. There are endless explanations for the spiked curiosity and interest in these fishes: 1) the increasing number of (and debate over) total species within the Micropterus genus (see Fisheries Blog post “Black Bass: How many species are there?“), 2) the desire to catch them all (big thrill to catch on a fly), 3) the increased realization that these fish behave differently in different systems, and 4) the exceptionally beautiful places they inhabit.

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Regardless of why we are paying attention to them, attempting to keep native riverine predators present in our flowing aquatic systems can only be a good thing.

The Shoal Bass (Micropterus cataractae) is a focal species for research and conservation efforts because it’s considered imperiled throughout its native range (the Apalachicola-Chattahoochee-Flint River basin), having faced population loss and decline throughout. The largest hit has been at the fringes of its range and in mainstem portions of the river near reservoirs. Being a habitat specialist, they just do not do well in reservoir-like conditions and are thus much worse off in the Chattahoochee River where there are 14 impoundments within the mainstem. Spawning habitat loss has also contributed to drops in recruitment and effective population levels. Potentially most alarming is the introduction of non-native bass into these waters where fish hybridize and wash out the genetic integrity of distinct species. (This is a much-needed topic for a future blog!)

I recently completed my MS at Auburn University where I studied Shoal Bass movement and habitat use within two Chattahoochee River tributaries using radio telemetry and side-scan sonar. We implanted radio tags in adult Shoal Bass and tracked their movements for a year and a half.

The two populations we looked at are considered viable and are not supplemented with stocked fish. Having spent 18 months on the water with 58 individuals, I can confirm and reaffirm what’s been found elsewhere within the Fall Line region: Shoal Bass move around seasonally and tend to congregate in rocky shoals with swift flows during spring months. The fact that 90% of our tagged fish migrated into these shallow rocky shoals in the spring and migrated out in the summer strongly suggests a seasonal preference for this specific type of habitat.

Young-of-year Shoal Bass were also collected from these areas, but recruitment seemed to differ with varying seasonal flows. High spring flows appeared to support greater levels of recruitment than low. While some pertinent and pressing questions were answered, as with all research, investigating one question opens the door to five more that suddenly seem to materialize. The results of this study will help us take another step forward in restoring populations and protecting habitat for this fish within non-impounded Fall Line tributaries. Let the good times roll!

We made it through the ten-mile paddle and begin to encounter our takeout location. All fish have been located today – even #591. She had moved down into the mile-long shoal complex along with eight others. I get that familiar melancholy feeling of the day’s journey ending, and our canoe slows down as it skates over the sleek sandy shoreline and comes to a stop.

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This is the ever-familiar feeling that NOW the trip has been sealed and we must go back to traveling by road. We stand up, stretch, gather our things, and begin hauling gear up to the truck. Last thing to grab is the clipboard and I quickly review who we found and who decided to be elusive today. In the truck, heading home, my curiosity and wonder peaks for the next group of fish – knowing the answers will slowly be revealed as we get back on the water tomorrow.

FISHBLOG - Cottrell 155Author: Amy Cottrell is a recent graduate of Auburn University’s School of Fisheries, Aquaculture and Aquatic Sciences. She currently works as a Fisheries Biologist II for Georgia DNR.

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