Uncharted Lancaster
Uncharted Lancaster reveals the county’s most fascinating stories—local history with odd twists, forgotten places, and the occasional brush with the supernatural. Each episode explores the hidden histories and long-buried secrets of Lancaster County, where legend, landscape, and local lore collide.
Uncharted Lancaster
Ancient Eel Weirs of the Susquehanna River
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Long before dams and modern fisheries, the Susquehanna River was home to an ingenious system of stone fishing traps built by Indigenous peoples to harvest migrating American eels. In this episode, we explore the mysterious V-shaped rock weirs that still lie hidden beneath the river’s surface—carefully engineered formations that funneled eels into traps, providing a reliable and protein-rich food source that could be smoked and stored through the winter.
Some researchers believe these sophisticated stone structures may be thousands of years old, possibly predating even the Egyptian pyramids. Today, many of them remain submerged or forgotten, but archaeologists, students, and conservationists are rediscovering them through satellite imagery while working to restore the Susquehanna’s fragile ecosystem. It’s a story where archaeology, ecology, and river lore come together—revealing just how central the eel once was to life along the Susquehanna.
Read more at UnchartedLancaster.com.
Cover Art: Native Lands by Artist Carol Oldenburg, 2021 hightlighting eel harvesting on the Susquehanna River
I want you to imagine just for a moment that you're you're out walking along a familiar riverbank.
SPEAKER_01Right. Like a spot you've been to a hundred times before.
SPEAKER_00Exactly. You're walking the dog, getting some fresh air. It's late summer, we're at low tide, and the water is running uncharacteristically low.
SPEAKER_01And clear?
SPEAKER_00Yeah, low and clear. Okay. And you're just looking out at the water, watching the current break over the river stones, when suddenly your brain does this little the stutter step.
SPEAKER_01Oh, I know that feeling.
SPEAKER_00Right. You notice that the rocks breaking the surface out there in the middle of the river, they aren't random.
SPEAKER_01They're not just scattered.
SPEAKER_00No, they aren't just scattered by the chaotic forces of nature. They form this massive, deliberate, geometric shape.
SPEAKER_01A V shape.
SPEAKER_00Yes, a perfect sprawling V pointing right down the center of the current.
SPEAKER_01It's it really is a moment of profound cognitive dissonance.
SPEAKER_00Oh, absolutely.
SPEAKER_01Because you are looking at something that has always been there resting right under your nose, but your brain is suddenly shifting gears to see the intelligence behind it.
SPEAKER_00Yeah, it clicks.
SPEAKER_01Exactly. The chaotic spattering of nature suddenly resolves into intent. You realize it's not geology, it's architecture, submerged, ancient architecture.
SPEAKER_00Aaron Powell And that is exactly what we are getting into today. We're doing a deep dive into an architectural mystery resting right at the bottom of the Susquehanna River.
SPEAKER_01And uh the rather bizarre alien-like creature it was actually built to catch.
SPEAKER_00Yes, the creature is wild. We're going to use satellite data, archaeological field reports, and even some historical paintings to completely change how you look at the water in your own backyard.
SPEAKER_01It's a fascinating stack of research today.
SPEAKER_00It really is. We're pulling from some incredible pieces today, including deep dives in the Bay Journal and Uncharted Lancaster.
SPEAKER_01Plus some really great data from the Susquehanna National Heritage Area.
SPEAKER_00Right, and field reports from the Pennsylvania Archaeology blog. Oh, and this stunning 2021 oil painting by an artist named Carol Oldenburg that really brings this all to life.
SPEAKER_01What makes this specific collection of research so compelling, I think, is how it forces us to reconsider the environments we we think we know best.
SPEAKER_00Yeah, we just take them for granted.
SPEAKER_01We do. We often view rivers just as moving water, maybe a place for recreation or a geographic boundary.
SPEAKER_00Right, just a place to kayak.
SPEAKER_01But the underlying theme of all these documents is that the natural world and human history are deeply, inextricably interwoven. Yeah. The evidence of massive, sophisticated civilizations and these ancient ecological engines is quite literally hidden just beneath the surface of the water.
SPEAKER_00Aaron Powell Just waiting for us to understand what we're looking at. And by the time we finish this deep dive, I promise you, you are going to look at your local landscapes completely differently.
SPEAKER_01It completely changes your perspective.
SPEAKER_00So let's start with that cognitive dissonance you mentioned earlier, standing on the riverbank and seeing that V shape. Our entry point into this whole world comes from a guy named Van Wagner.
SPEAKER_01Aaron Powell Right, the environmental science teacher.
SPEAKER_00Yeah, he's a science teacher. And he actually grew up on Bald Top Mountain, which looks right down over the Susquehan River in Pennsylvania.
SPEAKER_01It's a great vantage point.
SPEAKER_00It is. And as a kid, he would look down at the river during those low water periods we just described, and he'd spot these mysterious V shapes pointing downstream.
SPEAKER_01Aaron Powell It's such a universal childhood experience, you know? Noticing a pattern in nature and wondering if it means something.
SPEAKER_00Aaron Powell Exactly, like finding a weird footprint.
SPEAKER_01Yeah.
SPEAKER_00But what Wagner eventually learned, and what he now actually teaches, is that these weren't natural rock formations at all.
SPEAKER_01Aaron Ross Powell No, they were what are known as eelwears.
SPEAKER_00Aaron Powell Let me just stop you there. Because when I first read the term eelweir, I pictured um, I don't know, a modern metal grate or maybe some kind of commercial fishing net stretched across a dock.
SPEAKER_01Sure, like a modern trap.
SPEAKER_00Right. But from the drone footage Wagner eventually shot, you can see these are essentially underwater walls built entirely out of stacked river rocks.
SPEAKER_01Just a massive piles of stone.
SPEAKER_00Yeah, and they rise about three to five feet off the river bottom. The two walls form a giant funnel, that V shape, pointing downstream.
SPEAKER_01It's a brilliant design.
SPEAKER_00So as fish, specifically eels, are migrating down the river, the current and these stone walls naturally funnel them into the narrow point of the V.
SPEAKER_01Right.
SPEAKER_00And right at that narrow tip, they would be trapped in woven wooden baskets or easily speared.
SPEAKER_01Think about the physics of that design for a moment. It demonstrates a profound intuitive understanding of fluid dynamics and hydrologic flow. Water takes the path of least resistance, and so do the creatures traveling within it.
SPEAKER_00Yeah, they just go with the flow.
SPEAKER_01Exactly. By building these V-shaped walls, the engineers weren't trying to dam the river or fight its power.
SPEAKER_00They were harnessing it.
SPEAKER_01Right, harnessing its kinetic energy. As the river flows into the wide end of the funnel, the water is forced into a narrower and narrower channel.
SPEAKER_00Which speeds it up, right?
SPEAKER_01Yes, it accelerates the flow slightly, pushing the fish right toward the apex. It does the incredibly difficult work of gathering thousands of independent swimming creatures into a single concentrated point of harvest.
SPEAKER_00That's genius. But I really want to make sure we're conveying the sheer scale of these things to you listening.
SPEAKER_01Oh, the scale is massive.
SPEAKER_00We aren't talking about a little dam of pebbles you build in a creek as a kid on a Sunday afternoon. Wagner points out a specific site near Danville, Pennsylvania, where the weir is an eighth of a mile to a quarter of a mile wide at the top of the V. That's huge. A quarter of a mile.
SPEAKER_01To put that into perspective, that is more than four football fields laid end to end, spanning a rushing river.
SPEAKER_00Just imagine the backbreaking labor required to build that. You're standing waist deep in freezing, moving water.
SPEAKER_01Without any modern equipment.
SPEAKER_00Right. You don't have cranes, you don't have diesel excavators, you are bending down, picking up wet, slippery river stones that might weigh 20, 50, or 100 pounds each.
SPEAKER_01And you're fighting the current the whole time.
SPEAKER_00And you are stacking them, lock and key, against the force of the water. And you have to move thousands of tons of this rock to build just one of these structures.
SPEAKER_01The caloric expenditure just to create the trap is staggering.
SPEAKER_00It's mind-blowing.
SPEAKER_01Which is exactly why, for decades or even centuries, these structures were largely invisible to the modern public.
SPEAKER_00Aaron Powell Because they're underwater.
SPEAKER_01Right. Unless you had a severe drought and happened to be standing on a high vantage point like Bold Top Mountain, they just looked like natural rapids or riffles from the shoreline.
SPEAKER_00Yeah, the churning water just hides the geometry.
SPEAKER_01Exactly. But technology has completely shifted our ability to comprehend the scale of this phenomenon. The modern archaeological survey has been totally revolutionized by satellite imagery and lidar.
SPEAKER_00Wait, pause here a second.
SPEAKER_01Yeah.
SPEAKER_00I know what satellite imagery is, you know, basically Google Earth. But what exactly is LIDAR?
SPEAKER_01It's a great tool.
SPEAKER_00Aaron Powell And how is it spotting piles of submerged rocks? Doesn't water just reflect lasers?
SPEAKER_01That is a really great question. So LIDAR stands for light detection and ranging. Generally, it involves mounting a laser scanner on an airplane or a drone and firing millions of laser pulses at the ground to measure the exact distance to the surface.
SPEAKER_00Like radar but with light.
SPEAKER_01Exactly. And it creates a highly detailed 3D topographic map. Now you are correct that standard near infrared lidar bounces off the surface of water. Right.
SPEAKER_00It just reflects.
SPEAKER_01But archaeologists and geologists use a specific type called bathymetric lidar, which uses a green laser.
SPEAKER_00Aaron Powell A green laser.
SPEAKER_01Yeah. That green wavelength can actually penetrate the water column, bounce off the riverbed, and return to the sensor.
SPEAKER_00Oh wow.
SPEAKER_01So they can essentially strip away the water and see the exact naked geometry of the river bottom, revealing every single stacked stone.
SPEAKER_00Aaron Ross Powell That is wild. It's literally like draining the river with a computer. It really is. And the sources detail this amazing moment during the COVID-19 pandemic involving just regular satellite imagery.
SPEAKER_01Oh, the high school assignment.
SPEAKER_00Yeah. Van Wagner, the science teacher, is stuck at home. His field trips for his Lewisburg area high school students are canceled.
SPEAKER_01Like everything was back then.
SPEAKER_00Right. So he gives them a remote assignment, pull up Google Earth, and scour the satellite imagery of the Susquehanna River, looking for these telltale V shapes.
SPEAKER_01And they found them.
SPEAKER_00They found dozens of them just sitting there in the public satellite photos, completely unhidden.
SPEAKER_01It is a beautiful example of how access to technology has democratized the archaeological survey process. Seriously, high school kids sitting in their living rooms were mapping ancient infrastructure.
SPEAKER_00And their findings align perfectly with professional academic surveys. The North Carolina Office of State Archaeology conducted a massive fish weir recording survey back in 2019.
SPEAKER_01I read about that.
SPEAKER_00Across 10 states, utilizing this kind of remote sensing data and historical records, they identified 750 of these fish weirs.
SPEAKER_01750? That's incredible.
SPEAKER_00And Pennsylvania, which might surprise some people who think of this as a purely coastal phenomenon, had the second highest concentration in the entire survey.
SPEAKER_01Wait, really?
SPEAKER_00Yeah, with 141 documented weirs.
SPEAKER_01Okay. Looking for these weirs is exactly like looking at one of those magic eye posters from the 90s.
SPEAKER_00Oh, that's a perfect analogy.
SPEAKER_01You stare at the static pattern on the river, and it just looks like noise, just random ripples. They're completely invisible until you shift your perspective.
SPEAKER_00And look from above. Right, in this case, going straight up into the sky with the satellite. And once you finally see the V shape, your brain locks onto it. You literally can't unsee it.
SPEAKER_01It jumps out at you.
SPEAKER_00Suddenly it's everywhere. You follow the river bends on the map, and boom, there's another one and another one.
SPEAKER_01The structural variations they found are just as fascinating as the sheer numbers, too. They weren't just simple solitary V shapes. Oh. No. The aerial surveys revealed complex, adaptable engineering. Sometimes they were multiple connected V's forming a giant W or an intricate zigzag spanning the entire width of the river. And this wasn't just to catch more fish blindly.
SPEAKER_00What was it for?
SPEAKER_01The tips of the weirs, the apexes were constructed so they could be modular. They could be opened or closed depending on the season.
SPEAKER_00That's so smart.
SPEAKER_01They'd target fish migrating downstream toward the ocean, or alter the trap to catch different species migrating upstream toward the headwaters.
SPEAKER_00It is a highly tunable machine.
SPEAKER_01Precisely. Once you built the infrastructure, once you made that massive initial capital investment of labor to move the stones, which we know was a lot of labor. Right. The daily operational effort was incredibly minimal. It became a high yield, low-energy system.
SPEAKER_00Aaron Powell But that brings up a massive question. To understand why human beings would go through that staggering initial layer.
SPEAKER_01Moving countless tons of rock.
SPEAKER_00Yeah, to build a quarter mile wide funnel, we really have to look at who built them, when they built them, and what kind of civilization required that much food.
SPEAKER_01Exactly.
SPEAKER_00Because you don't build a quarter mile stone funnel in a river for a casual weekend fishing trip. You build that to feed thousands of people.
SPEAKER_01That leads us directly to the timeline and the builders. These weirs were primarily built by Native American civilizations. The geographic correlation is undeniable. Almost every single one of these weirs found in Pennsylvania is located adjacent to, or very near, a documented pre-contact or contact period Native American village site.
SPEAKER_00And the diet of these villages relied heavily on what they were catching. We have a master's thesis by a researcher named Alan Lutons on prehistoric fish weirs in eastern North America.
SPEAKER_01It's a key piece of research.
SPEAKER_00He notes that fish, and specifically eels, played a massive, vital role in the diets of Native Americans along these rivers well before what archaeologists call the Woodland period.
SPEAKER_01Right, which stretches from 500 BC to AD 1100.
SPEAKER_00Right.
SPEAKER_01I want to pause on that term, the woodland period, because it carries a lot of weight in North American archaeology. Oh so. Generally, the woodland period is characterized by a massive cultural shift. The adoption of agriculture, the making of pottery, and the establishment of more permanent sedentary villages.
SPEAKER_00So people stopped moving around as much.
SPEAKER_01Right. Before this, populations were thought to be more nomadic following seasonal food sources. Okay. But the existence of these massive weir before the woodland period forces a paradigm shift. Really? Yes. It means these civilizations achieved sedentary, complex municipal societies without needing to rely on traditional terrestrial farming. Trevor Burrus, Jr.
SPEAKER_00Oh, because the river was providing so much food.
SPEAKER_01Exactly. They were anchored to the river because the river, via these weirs, was providing the caloric equivalent of hundreds of acres of agricultural land.
SPEAKER_00That is an incredible way to look at it. The river was their farm, and the weir was the tractor.
SPEAKER_01That's a great way to put it.
SPEAKER_00And you can actually see the cultural footprint of this diet embedded in the very language of the region today. The linguistic evidence is hiding in plain sight, much like the weirs themselves.
SPEAKER_01Right, the place names.
SPEAKER_00Take Swatara Creek near Harrisburg. The name Swatara is derived from an indigenous language translating to where we feed on eels.
SPEAKER_01It's right there in the name.
SPEAKER_00In fact, Swatara Township actually features an eel right on its official municipal crest today.
SPEAKER_01That's amazing.
SPEAKER_00And the city of Shimokin, which drains into the Susquehanna. In the language of the Delaware tribe, Shimokin literally means eel creek.
SPEAKER_01The land itself holds the memory of its primary utility.
SPEAKER_00It really does.
SPEAKER_01But establishing the precise age of these structures presents a unique, almost frustrating challenge for archaeologists. The Pennsylvania Archaeology blog delves into this.
SPEAKER_00Oh, the dating problem.
SPEAKER_01Right. How do you date a pile of rocks in a river? You can't carbon date stone. A rock is millions of years old, regardless of whether a human picked it up yesterday or 10,000 years ago.
SPEAKER_00Aaron Powell Right. If I pick up a rock from my driveway and drop it in the creek, a scientist a thousand years from now carbon dating, that rock is just going to find out when the earth cooled, not when I dropped it.
SPEAKER_01Exactly the problem. The rocks themselves tell you absolutely nothing about human interaction time frames.
SPEAKER_00Aaron Powell So what do they do?
SPEAKER_01Furthermore, the river is an incredibly dynamic, violent environment. Spring floods, massive ice flows scouring the bottom, and constant sediment movement continually dismantle and bury these structures.
SPEAKER_00So they're getting constantly messed up.
SPEAKER_01Right. They were highly likely rebuilt, modified, and repaired by multiple generations over thousands of years.
SPEAKER_00Okay, so how do we know how old they are?
SPEAKER_01To date them, archaeologists have to play a game of microscopic hide and seek. They have to excavate down into the mud beneath the rocks and look for organic material that was trapped within the original construction of the structure.
SPEAKER_00Like wood.
SPEAKER_01Specifically, yes. They look for the remnants of the wooden stakes that anchored the rocks in place, or fragments of the woven wooden capture baskets that were placed at the very tip of the V.
SPEAKER_00And when they actually managed to find and carbon date that wood, the results are mind-blowing.
SPEAKER_01Yeah.
SPEAKER_00Let's look at the Sebasticook Lake Fishware Complex up in Maine.
SPEAKER_01That's a famous site.
SPEAKER_00Archaeologists successfully recovered wood from a capture basket buried in the anaerobic mud there, and the radiocarbon dating placed it at 3,000 BC.
SPEAKER_013,000 BC.
SPEAKER_00That is roughly 5,000 to 6,000 years ago.
SPEAKER_01Let's contextualize that time frame on a global scale.
SPEAKER_00Please.
SPEAKER_01The Great Pyramid of Giza in Egypt was built around 2500 BC. Wow. So these Native American engineering projects in the rivers of North America predate the Great Pyramids by 500 years.
SPEAKER_00Let's just sit with that for a second. We are trained to view ancient monumental history as something that happens in Egypt or Mesopotamia or Greece. Always somewhere else. Right. We think of ancient ruins as temples in the desert. But there is civic infrastructure resting in the mud behind a Pennsylvania suburb, underneath kayaks and fishing boats, that was already ancient before the first stone of the Great Pyramid was laid.
SPEAKER_01It's staggering to think about. It's highly probable.
SPEAKER_00We are talking about infrastructure as old as recorded human civilization.
SPEAKER_01It shatters the reductive, often inaccurate view of early Native Americans purely as nomadic hunter-gatherers treading lightly on the earth, leaving no trace.
SPEAKER_00Yeah, this leaves a huge trace.
SPEAKER_01These weirs represent permanent, monumental municipal infrastructure. They represent a civilization engineering its environment on a massive, permanent scale to guarantee caloric security across generations.
SPEAKER_00To really visualize what this looked like at its peak, I want to bring in one of the most unique sources we have today. Yes. It's a 2021 oil painting by an artist named Carol Oldenburg, titled Native Lands. It's a stunning piece of visual research.
SPEAKER_01It really captures the feeling.
SPEAKER_00Imagine you're looking down from a high bluff overlooking a wide rushing section of the Susquehanna River in deep autumn. The trees on the banks are blazing orange and yellow.
SPEAKER_01Beautiful.
SPEAKER_00Out in the cold gray-blue water. You don't just see one V shape, you see an entire network of them. It's a massive W shape spanning the entire width of the river.
SPEAKER_01Oldenburg captures the scale of human activity required to operate the system during the migration.
SPEAKER_00Yeah, you can see people in the water.
SPEAKER_01In the painting, there are figures out in the water, standing at the apexes of the weirs, actively harvesting the trapped fish from the baskets.
SPEAKER_00And books, too.
SPEAKER_01There are small, maneuverable canoes navigating the calmer pools of water immediately behind the stone walls, ferrying the massive touch to the shore.
SPEAKER_00And on the near bank, she paints this sprawling palisaded village. It's surrounded by a high defensive wooden fence, and inside there are these massive, bark-covered longhouses.
SPEAKER_01It's a thriving community.
SPEAKER_00But the detail that really strikes me is the smoke. There are thick plumes of white smoke rising from multiple fires within the village. That smoke tells the real story of survival here.
SPEAKER_01That smoke represents the preservation process, which is the entire point of the endeavor.
SPEAKER_00Because you can eat it all at once.
SPEAKER_01Exactly. If you catch hundreds or thousands of pounds of eel in a matter of days during a massive migration run, you have a secondary problem. Spoilage. Right. The Native Americans, like the Onondagas of the Iroquois nation, whom early European colonists actually documented roasting eels at the river's headwaters.
SPEAKER_00Oh, they wrote that down.
SPEAKER_01They did. They would spend weeks smoking and drying the eel meat. Eels are incredibly calorie-dense.
SPEAKER_00They're pretty fatty, right?
SPEAKER_01They have an exceptionally high fat content compared to other freshwater fish like bass or trout. Smoking them preserves that crucial fat and protein.
SPEAKER_00That gets them through the winter.
SPEAKER_01Turning it into a stable food source that will sustain the entire village through the brutal, freezing, barren winters of the Northeast.
SPEAKER_00And the sheer volume of food we are talking about is staggering. The Pennsylvania Fish and Boat Commission notes that historically, estimates suggest eels made up 25% of all fish biomass in the Susquehanna River basin.
SPEAKER_0125%.
SPEAKER_00One out of every four pounds of fish in that entire massive sprawling river system was an eel.
SPEAKER_01It fundamentally changes our understanding of the regional ecology. The Susquehanna wasn't just a river, it was a conveyor belt of high density calories.
SPEAKER_00A conveyor belt, exactly.
SPEAKER_01The civilizations built on its banks were deeply attuned to the rhythms of this specific creature. But to truly appreciate the genius of the people who built these weirs, we have to understand the creature they were catching.
SPEAKER_00It's a weird one.
SPEAKER_01Because the American eel possesses a life cycle so bizarre, so incredibly hidden, that modern scientists only fully figured it out relatively recently.
SPEAKER_00And the Native Americans had to understand this creature intimately. They knew exactly when to rebuild the traps after the spring floods, exactly when the migration would happen.
SPEAKER_01They timed it perfectly.
SPEAKER_00They synchronized their whole calendar to it. So let's talk about the target of these megastructures. The bizarre and brilliant American eel. Now, first things first, we need to clear a major misconception up right away.
SPEAKER_01I think I know what's coming.
SPEAKER_00When people hear eel, they immediately think of a giant terrifying thing that's going to electrocute them if they touch the water.
SPEAKER_01It is an incredibly persistent myth. The electric eel, famously found in South America, is actually not a true eel at all.
SPEAKER_00Wait, really?
SPEAKER_01No. It's an entirely different order of fish, scientifically more closely related to carp and catfish.
SPEAKER_00Oh wow. I had no idea.
SPEAKER_01The American eel, the species we are discussing, is a true eel, part of the Anguillidae family. It has absolutely no biological mechanism to generate electricity.
SPEAKER_00No electric shocks, thank goodness. But they do have some, let's say, unique physical characteristics that make people a little squeamish.
SPEAKER_01They're not the most conventionally attractive fish.
SPEAKER_00No. The Susquehanna National Heritage Area document notes that at first glance, people often have this visceral, almost evolutionary fear response because they look so much like snakes. It makes sense. It totally does. You reel in a five-foot-long, wiggling, pure muscle tube from the river, and your reptilian brain screams, snake.
SPEAKER_01But if you bypass that initial fear response and look closely, as the researchers suggest, they have distinct fish characteristics.
SPEAKER_00Like what?
SPEAKER_01They have these small pictoral fins right behind their heads that look almost like little dumbo ears.
SPEAKER_00Dumbo ears. That's actually kind of cute.
SPEAKER_01It softens their appearance quite a bit once you notice them. However, the other trait that turns people off is their texture.
SPEAKER_00Oh, the slime. We have to talk about the slime.
SPEAKER_01We do. They are coated in a remarkably thick viscous layer of mucus.
SPEAKER_00Gross.
SPEAKER_01But functionally, this slime. Slime is an evolutionary marvel. It isn't just gross, it's tactical armor.
SPEAKER_00Tactical armor slime.
SPEAKER_01It serves as a physical barrier that makes it incredibly difficult for predators like birds of prey, otters, or larger fish to grip them. They literally slip right out of a heron's beak. Furthermore, the mucus contains potent antimicrobial properties. Because they spend so much time burrowing in the mud and sediment, they are constantly exposed to bacteria.
SPEAKER_00So it keeps them from getting sick.
SPEAKER_01The slime protects them from infections. It's their primary immune defense system.
SPEAKER_00So no electricity, little dumbo ears, and a coat of tactical antibacterial armor slime.
SPEAKER_01That's the one.
SPEAKER_00But where the American eel goes from just weird fish to absolute biological marvel is its life cycle. The experts point out that for a very long time, this life cycle was a complete mystery to Western science because no one had ever caught a pregnant female eel in freshwater, ever.
SPEAKER_01Which baffled biologists for centuries.
SPEAKER_00You could catch millions of them, but you'd never find eggs.
SPEAKER_01This brings us to the concept of migratory fish patterns. Most people are familiar with the migration of salmon or the American shad. Shad are what biologists call anodromus. This means they are born in freshwater rivers, they migrate out to the saltwater ocean where they spend their adult lives growing and maturing.
SPEAKER_00And then they come back.
SPEAKER_01And then they return to the freshwater rivers to spawn and lay their eggs. The American eel is the exact opposite.
SPEAKER_00They do it backwards.
SPEAKER_01They are North America's only catadromus species. They are born in the saltwater ocean, migrate thousands of miles into freshwater rivers to grow and mature, and then return to the ocean to spawn.
SPEAKER_00Hold on, let me get this straight. You're telling me an eel caught in a creek in central Pennsylvania was born in the middle of the Atlantic Ocean.
SPEAKER_01Yes.
SPEAKER_00How does a tiny freshwater fish cross the ocean without getting eaten?
SPEAKER_01Yeah.
SPEAKER_00Let's trace this journey because it is genuinely like something out of a fantasy novel.
SPEAKER_01It really is phase one.
SPEAKER_00Birth. Every single American eel on the continent is born in one specific place on Earth, the Sargasso Sea.
SPEAKER_01The Sargasso Sea is a fascinating geographical and oceanographic anomaly.
SPEAKER_00Where is that exactly?
SPEAKER_01It's located in the middle of the North Atlantic Ocean, roughly east of the Bahamas and northeast of Bermuda. What makes it unique is that it is the only sea on Earth that has no land boundaries whatsoever.
SPEAKER_00Wait, really? No coasts?
SPEAKER_01None. It is defined entirely by ocean currents. Four massive distinct ocean currents form a massive gyre, a slowly rotating, calm vortex of water in the center of the Atlantic.
SPEAKER_00Like a slow whirlpool.
SPEAKER_01It's named for the sargassum seaweed, a type of brown macroalgae that floats in massive, dense, tangled mats on its surface, providing a unique floating ecosystem.
SPEAKER_00So deep in this swirling, calm vortex of seaweed, the eel eggs hatch. And this takes us to phase two. When they hatch, they don't look anything like eels. Not at all. For the first year of their lives, they are called leptocephalus. They are completely transparent, flattened sideways, and shaped exactly like a willow leaf.
SPEAKER_01And that shape is not an accident. It is highly specialized for oceanic drift.
SPEAKER_00How so?
SPEAKER_01At this stage, they have virtually no swimming power. They are microscopic, but their broad, flat, leaf-like shape allows them to catch the deep ocean currents, much like a sail catching the wind.
SPEAKER_00Oh wow.
SPEAKER_01They drift passively within the Gulf Stream for thousands of miles. This journey takes roughly an entire year, slowly sweeping them northward and westward toward the eastern coast of North America.
SPEAKER_00So they're just drifting for a year.
SPEAKER_01And their transparency is their only defense mechanism in the open ocean. They are basically invisible to predators.
SPEAKER_00They're essentially tiny transparent sails riding the ocean currents. So after a year, they finally hit the coastline and we enter phase three.
SPEAKER_01The transformation phase.
SPEAKER_00As they approach the shallower coastal waters, they undergo a massive physical transformation. They lose the flat leaf shape and become tiny, cylindrical, transparent versions of an adult eel.
SPEAKER_01At this stage, they are called glass eels.
SPEAKER_00Because you can literally see their internal organs through their skin.
SPEAKER_01As they arrive at the estuaries and sense the freshwater outflows from rivers like the Susquehanna, a profound chemical trigger goes off.
SPEAKER_00What happens?
SPEAKER_01Their instinct drives them to turn away from the ocean and swim upstream. As they enter the brackish water, the mixture of salt and fresh and begin actively swimming against the current, they develop pigmentation, turning gray or brown to blend in with the river bottom.
SPEAKER_00Which brings us to phase four.
SPEAKER_01Uh-huh.
SPEAKER_00The elver stage. Wait, I have to ask about this stage. They are still small, maybe a few inches long. How do they navigate rushing rapids and massive river rocks if they are that small? Do they just swim really hard?
SPEAKER_01Swimming against a roaring rapid would exhaust and kill them. This is where their biology provides another incredible adaptation. They are incredibly determined climbers. Climbers? Remember that thick mucus coat? The slime. They use it to essentially adhere to wet surfaces via surface tension because they can absorb oxygen directly through their skin as long as they stay moist. They don't even need to stay in the main water column.
SPEAKER_00Are you saying they leave the water?
SPEAKER_01They will literally slither out of the raging water and climb up wet rocks, damp moss, and the muddy edges of the riverbank, bypassing the strongest currents entirely to push deeper into the watershed.
SPEAKER_00That is horrifying, but amazing. A swarm of tiny snakes climbing up the wet rocks in the dark.
SPEAKER_01It's very effective.
SPEAKER_00So they finally find a suitable habitat in a freshwater river or a small inland creek. This is phase five. They become what biologists call yellow eels. This is their growth phase.
SPEAKER_01And this phase lasts a very long time.
SPEAKER_00Here is the crazy part. They can live in this phase completely isolated in a freshwater creek in Pennsylvania for anywhere from two to forty years.
SPEAKER_01Forty years.
SPEAKER_00They can grow up to five feet long, just hanging out under a log, eating insects, small fish, and crustaceans.
SPEAKER_01They are biding their time. The entire purpose of this decades-long freshwater phase is accumulating massive fat reserves necessary for the final, most arduous phase of their lives.
SPEAKER_00The trip back.
SPEAKER_01When specific environmental cues, which frankly marine biologists still don't fully understand, trigger them, they undergo one last dramatic transformation into silver eels. Their bodies thicken, their fat content peaks, even their eyes physically enlarge, adapting to see in the deep, dark ocean depths they are about to face. And they begin the massive migration back downstream in the fall.
SPEAKER_00Here is where it gets absolutely mind-blowing. The female eels at this point are carrying up to two million eggs inside them.
SPEAKER_01Two million.
SPEAKER_00And the journey from a creek in Pennsylvania back to the middle of the Sargasso Sea in the Atlantic Ocean is so brutally exhausting that they need every ounce of energy they can muster. So what do they do?
SPEAKER_01This is the craziest part.
SPEAKER_00They actually absorb their own digestive tracts for extra fuel.
SPEAKER_01It is an extreme biological process, essentially a form of programmed cell death and reabsorption.
SPEAKER_00How does a creature eat its own stomach?
SPEAKER_01Well, the energy required simply to maintain a functioning digestive system, the blood flow, the cellular turnover is immense.
SPEAKER_00So they just shut it off.
SPEAKER_01By shutting down the digestive tract completely and metabolizing those organs, they achieve two things. They free up physical space inside their body cavity to carry more of those two million eggs. Oh. And they gain a massive final calorie boost to power their muscles for a thousand mile swim.
SPEAKER_00It's like a spaceship deliberately burning its own life support system for fuel because it knows it's on a one-way trip.
SPEAKER_01That's exactly what it is.
SPEAKER_00They absorb their stomachs because they know they will never ever eat again. They swim to the Sargasso Sea, they spawn, and then they die.
SPEAKER_01What's extraordinary about this from a scientific perspective is how we actually discovered it.
SPEAKER_00Oh, right, because no one had seen it happen.
SPEAKER_01Because the adults died deep in the ocean and the larvae look like transparent leaves. For centuries, no one made the connection that they were the same animal.
SPEAKER_00They thought they were two different species.
SPEAKER_01Yes. The breakthrough involved incredible historical detective work, primarily by a Danish biologist named Johannes Schmidt in the early 20th century. What did he do? Scientists literally had to charter boats and drag plankton nets across the Atlantic Ocean for years.
SPEAKER_00Just looking for these transparent leaves.
SPEAKER_01They would catch the transparent leaf larvae and basically play a massive game of hot and cold.
SPEAKER_00How does that work?
SPEAKER_01They measured them and mapped where the larvae got smaller and smaller, tracing them backward against the ocean currents until all the smallest specimens pointed to one location, the Sargasso Sea.
SPEAKER_00That is just an incredible piece of scientific dedication. But let's bring this back to the Native American weirs we started with. The massive stone architecture. The builders of those massive stone V's didn't have oceanography vessels. They didn't know about the Sargasso Sea or Johannes Schmidt.
SPEAKER_01No, they didn't.
SPEAKER_00But they had such a profound observational knowledge of their local environment that they knew exactly when this invisible underwater biological clock was ticking. They had it down to a science. They knew that every fall, driven by cues from an ocean they had never seen, these massive, fat-laden adults would be heading downstream on their one-way trip. And that was the exact moment to close the traps.
SPEAKER_01It speaks to a level of generational empirical science that we often fail to credit to indigenous populations.
SPEAKER_00Oh, Tywe.
SPEAKER_01They observed the patterns of the river with such precision that they perfectly synchronized their civilization's entire food harvest with a biological event driven by ocean currents thousands of miles away.
SPEAKER_00But this incredible journey isn't just a biological marvel or a calorie source for ancient civilizations. It turns out this bizarre, slimy, ocean-going fish is the literal lifeblood of the river's entire water quality today.
SPEAKER_01It's a crucial keystone species.
SPEAKER_00And it all relies on a completely unexpected, frankly, weird, symbiotic friendship.
SPEAKER_01Ecology is fundamentally about relationships. Nothing exists in isolation.
SPEAKER_00Right.
SPEAKER_01And in the Susquehanna River ecosystem, one of the most critical relationships is between the American eel and a remarkably unassuming creature.
SPEAKER_00The Eastern Elliptio muscle. The Eastern Elliptio is the most common freshwater muscle in the Susquehanna. Now, normally when you think of muscles, you just picture a shell sitting there on the bottom of the river, half buried in the mud, filtering water.
SPEAKER_01Pretty boring, right?
SPEAKER_00Yeah, you don't think of them as active participants in an underwater taxi service. But the life cycle of this muscle is intimately, almost exclusively, tied to the American eel.
SPEAKER_01To understand why, you have to look at the muscle's primary problem, mobility.
SPEAKER_00Right, they can't swim.
SPEAKER_01Muscles are largely sedentary. If a muscle population just reproduced exactly where it sat, the local resources, the algae and nutrients in that specific spot of the river would quickly be depleted.
SPEAKER_00They'd eat themselves out of house and home.
SPEAKER_01Furthermore, the water current is always pushing things downstream. To survive as a species, they need a mechanism to distribute their young upstream against the current to colonize new territory.
SPEAKER_00So how do they move upstream?
SPEAKER_01So, over millions of years of co-evolution, the eastern elliptio muscle developed a parasitic yet ultimately symbiotic relationship specifically with the eel.
SPEAKER_00How does a shell hitch a ride on a fish? When the female muscles are in the final stages of reproduction, they release these tiny microscopic larvae called glocidia into the water column.
SPEAKER_01Right.
SPEAKER_00And these larvae are looking for one very specific host. The gills of a passing American eel.
SPEAKER_01The mechanism is fascinating. When an eel swims by, displacing the water, the muscle senses the disturbance and releases the larvae.
SPEAKER_00Like a motion sensor.
SPEAKER_01Exactly. These microscopic larvae have tiny specialized hooks. When they get drawn into the eel's mouth and pass over its gills to breathe, the larvae snap shut, attaching themselves directly to the delicate filaments of the eel's gills. Now, the word parasitic sounds harmful, and the host's body does react. The eel's gill tissue actually forms a small cyst around the larva to heal the micro wound.
SPEAKER_00Which covers the baby muscle.
SPEAKER_01Which inadvertently completely protects the baby muscle. But in this case, the burden on the eel is minimal. It doesn't significantly harm or suffocate the fish.
SPEAKER_00So the eel just swims away.
SPEAKER_01The eel simply acts as an unwitting, armored, underwater taxi. As the eel continues its determined migration upstream, climbing rocks and pushing into new creeks, it carries these encapsulated larval mussels with it.
SPEAKER_00They ride the eel express for about two to four weeks, and then once they've been transported miles upstream into new, uncolonized territory, they undergo a transformation.
SPEAKER_01They break out.
SPEAKER_00Yeah, they break out of the cyst, drop off the gills, settle into the riverbed mud, and grow into juvenile mussels. It is a brilliant evolutionary hack for a creature without legs or fins.
SPEAKER_01It really is. But this complex life cycle raises a terrifying ecological question. What happens when a keystone species in this chain vanishes?
SPEAKER_00Because the implications for the broader ecosystem and even human populations are massive.
SPEAKER_01To understand why, we have to look at what these mussels actually do once they settle into the mud. The eastern elliptio muscle is incredibly long-lived. They can live to be a hundred years old.
SPEAKER_00A hundred years. Just sitting on the bottom of the river pumping water.
SPEAKER_01Pumping and filtering incessantly. A single adult eastern elliptio muscle filters up to 15 gallons of water every single day.
SPEAKER_0015 gallons a day per muscle.
SPEAKER_01They pull in murky river water, extract algae, bacteria, and suspended sediment for food, and then expel clean, clear water back into the river. They are the river's liver.
SPEAKER_00So let's look at the math here, because the numbers laid out in the research are staggering. Currently, the upper Susquehanna has a decent population of these mussels, but biologists noticed a huge problem. They're aging.
SPEAKER_01They're getting old.
SPEAKER_00They are the geriatric generation of mussels, 60, 70, 80 years old. There are very few young ones. Why? Because not enough eels are making it upstream to act as taxis for the babies. If we could restore the eel population and thereby restore the muscle population to historical levels, the estimates are that 280 million elliptial mussels could filter between two to six billion gallons of water a day.
SPEAKER_01Billions of gallons, every single day. In doing so, they would physically remove nearly 78 tons of suspended sediment from the water column daily.
SPEAKER_00Seventy-eight tons of dirt.
SPEAKER_01Sediment is one of the absolute major contributors to poor water health. When water is clouded with sediment, sunlight can't penetrate.
SPEAKER_00Which kills the plants.
SPEAKER_01If sunlight can't penetrate, submerged aquatic vegetation dies. If the plants die, the dissolved oxygen levels crash and other fish species suffocate.
SPEAKER_00It's a chain reaction.
SPEAKER_01Sediment also carries agricultural pollutants like phosphorus and nitrogen. That the muscles lock all of that away in the riverbed.
SPEAKER_00Wait, let me make sure I have this domino effect straight. If we lose the slimy snake-like fish that everyone thinks is gross, which we almost did. Then the hundred-year-old water filtering mussels can't have babies because they don't have a ride upriver.
SPEAKER_01Correct.
SPEAKER_00And as the old mussels die out of old age, the river water stops being filtered.
SPEAKER_01Yeah.
SPEAKER_00And because the Susquehanna River provides nearly half of all the freshwater flowing into the entire Chesapeake Bay, if the mussels go, the entire Chesapeake Bay, which is a massive economic and ecological engine itself, literally chokes on sediment.
SPEAKER_01It is the perfect illustration of an ecological cascade. We have a tendency in conservation to view ecosystems through the lens of individual charismatic species, saving the bald eagle or the dolphins.
SPEAKER_00Right.
SPEAKER_01But the reality is a deeply integrated mechanical network. The health of the largest estuary in the United States, the Chesapeake Bay, is functionally dependent on the gill traffic of a migratory eel hundreds of miles upstream. That's crazy. The formula is beautifully simple. More eels equals more muscles, which equals cleaner water for everyone.
SPEAKER_00And unfortunately, human intervention in the modern era pushed exactly that first domino, severing the connection and nearly collapsing a system that had worked flawlessly for millennia.
SPEAKER_01We really messed it up.
SPEAKER_00We established earlier that Native Americans managed this resource sustainably for thousands of years. But then European colonists arrived.
SPEAKER_01The arrival of European colonists brought a massive shift in how the river was utilized and industrialized.
SPEAKER_00What did they do?
SPEAKER_01Initially, the colonists recognized the undeniable value of the Native American weirs. They quite literally took them over, repairing the stone walls, and eventually began building their own using similar techniques.
SPEAKER_00They just copied the homework.
SPEAKER_01The historical records cited by Lutons show settlers operating massive stone and stake weirs in rivers all along the East Coast.
SPEAKER_00Van Wagner, our science teacher from the beginning, unearthed some incredible historical documents right out of his hometown of Danville.
SPEAKER_01Oh, the catch records.
SPEAKER_00He found records showing that in September of 1914 at the Danbury Weir, fishermen pulled in three tons of eels in just 10 days.
SPEAKER_01Three tons.
SPEAKER_00Three tons.
SPEAKER_01It wasn't just subsistence fishing, it was a major economic and cultural event. Wagner notes in his research that when word spread through the town that the fall eel migration was starting, men would literally walk off their jobs in the factories or fields to man the nets on the river.
SPEAKER_00Just abandon their jobs.
SPEAKER_01Boys would walk the streets of Danville with heavy stringers of eels slung over their backs, selling them door to door to families, restaurants, and bars. It was an absolute delicacy and a vital economic driver for these river towns.
SPEAKER_00And before we think of this as just some old-timey historical quirk like churning your own butter, the demand for eel today is still massive, but it's shifted globally.
SPEAKER_01It's a huge international market now.
SPEAKER_00The sources point out that juvenile eels, those tiny elvers coming in from the ocean, are highly prized for international aquaculture. For sushi, right. Yes. They are caught wild here in the U.S. and shipped live to Asia to be raised on farms for the massive sushi market, specifically for dishes like hunagi, which is freshwater eel, or anago, the saltwater eel.
SPEAKER_01Because European and Asian native eel species have been so brutally overfished and their habitats destroyed, the demand for American elvers skyrocketed.
SPEAKER_00The prices are insane. In Maine, where the fishery is heavily regulated, the price for a single pound of these tiny live glass eels averaged$1,500 over a 10-year period.
SPEAKER_01$1,500 a pound, which demonstrates the immense continuous economic pressure on the species.
SPEAKER_00Oh, absolutely.
SPEAKER_01However, while overfishing is a major concern globally, the true devastating impact on the Susquehanna eel population specifically wasn't the fishermen at the weirs.
SPEAKER_00What was it?
SPEAKER_01It was the industrialization of the river itself for power generation, specifically the construction of monolithic hydroelectric dams.
SPEAKER_00This is where the story gets really tragic. The lower Susquehanna River, down near Maryland and the Pennsylvania border, is blocked by four massive hydroelectric dams.
SPEAKER_01Massive obstacles.
SPEAKER_00The most notorious for fish migration is the Conowingo Dam. It is a ninety-four-foot tall wall of solid concrete, stretching nearly a mile across, and it sits just ten miles from where the river dumps into the Chesapeake Bay. Just ten miles.
SPEAKER_01The timing of the historical records highlights the slow motion nature of this ecological collapse. You mentioned the massive three-ton catch in Danville in 1914. What's crucial to realize is the timeline. 1914 was actually four years after the Holtwood Dam, further downstream, had already completely blocked the river.
SPEAKER_00Wait, I need to do the math on that. If the dam blocked the river in 1910, stopping anything from coming up from the ocean, how were they catching tons of eels up in Danville in 1914?
SPEAKER_01Because of the eels' incredible lifespan. The eels they were catching in Danville in 1914, and indeed the eels that continued to be caught all the way into the 1940s and 50s were the trapped adults.
SPEAKER_00The yellow eels.
SPEAKER_01Remember phase five. Yelly eels can live up to 40 years in fresh water. The dams stopped the babies, the elvers, from coming up, but the adults that were already upstream were stuck. Wow. For decades, the fishermen were simply harvesting a doomed, aging population that had absolutely no way to replace itself. They were catching ghosts. The population was functionally extinct. It just took 40 years for the bodies to run out.
SPEAKER_00That is genuinely heartbreaking. You think the river is healthy because you were still catching fish, but you were just harvesting the remnants of a severed cycle.
SPEAKER_01Exactly.
SPEAKER_00And look, it's not like the engineers in the 20th century didn't know dams blocked fish. The government and power companies spent tens of millions of dollars building fish ladders at these dams to try and mitigate the damage. These are basically a series of ascending concrete pools that allow fish to jump and swim their way up and over the dam.
SPEAKER_01Yeah.
SPEAKER_00But here's the problem.
SPEAKER_01Yeah.
SPEAKER_00Those ladders were designed specifically for American shad.
SPEAKER_01Which highlights the danger of engineering a solution without fully understanding the diverse biology of the ecosystem you're trying to fix.
SPEAKER_00Yeah, shad aren't eels.
SPEAKER_01Shad and eels have completely different physical capabilities and migratory behaviors. Shad are powerful swimmers. They migrate during the daylight hours, and they possess the swimming power to fight the strong, deep midriver flows.
SPEAKER_00So the ladders worked for them?
SPEAKER_01The fish ladders were designed to mimic that specific environment. Strong, deep daytime currents rushing down concrete steps.
SPEAKER_00But the tiny juvenile eels The elvers are completely different. We talked about how they climb.
SPEAKER_01Right, they slither.
SPEAKER_00They migrate almost exclusively at night to avoid predators. And because they are so small, just a few inches long, they absolutely cannot fight a main rushing current. They hug the very edges of the river, utilizing their slime to slither up wet rocks in the slow-moving, shallow margins.
SPEAKER_01So a roaring deep water fish ladder in the middle of the river is completely 100% useless to an eel.
SPEAKER_00They can't use it at all.
SPEAKER_01They just hit the 94-foot concrete wall of the dam and stop. They pool at the bottom by the millions, unable to pass.
SPEAKER_00However, there is a modern restoration effort that addresses this biological reality. And it is surprisingly clever and remarkably simple, especially when compared to those multimillion dollar concrete shad ladders.
SPEAKER_01Oh, the eelway.
SPEAKER_00The eelway. The sources describe this system established at the Connowingo Dam. When I read the mechanics of how this worked, I actually laughed out loud because it is so ingeniously low-tech. It really is. It's essentially an 18-inch wide aluminum ramp that runs from the base of the river below the dam all the way up to a holding tank at the top. Just a little metal ramp. It's lined with a specialized textured netting, almost like artificial terse, that gives the elvers something to grip with their mucus. And to attract them to the base of the ramp, they use a pipe that bumps just six gallons of water a minute down the ramp.
SPEAKER_01Six gallons a minute is barely a trickle.
SPEAKER_00It's nothing.
SPEAKER_01But to a tiny elver migrating at night, that gentle trickle perfectly mimics the slow-moving edge of a natural small stream entering the main river. It leverages their natural instincts flawlessly.
SPEAKER_00That's so smart.
SPEAKER_01The elvers sense the gentle flow in the dark. They use their natural climbing ability to scale the wet, textured ramp, and they drop right over the top into an aerated holding tank.
SPEAKER_00And it works. It works incredibly well. Once they are safely in the tank at the top of the ramp, biologists literally scoop them out with nets, put them in a specialized aerated tank on the back of a pickup truck, drive them up the highway past all four of the massive hydroelectric dams, and dump them back into the upper river so they can continue their journey. Since 2008, they have physically trucked over two million eels upstream this way. In 2021 alone, they moved over 620,000 eels.
SPEAKER_01It is a phenomenal logistical achievement, and it is an absolute lifeline for the upper river ecosystem and those aging 80-year-old muscle populations we talked about. By manually reintroducing the eels, they are kickstarting that ecological engine again. However, we must acknowledge the tragic reality and the ongoing engineering challenge that this solution presents.
SPEAKER_00Yeah, there is a catch to the pickup truck method.
SPEAKER_01A massive catch. We can truck millions of juvenile eels upstream, and they will live their 20 or 30 years in the freshwater, filtering the water via the muscles, growing large and healthy. Right. But remember the catadromous life cycle. To spawn and create the next generation, those adults must return to the Sargasso Sea, which means that massive, five foot-long, egg-laden female must travel back downstream.
SPEAKER_00And the pickup truck isn't there to give her a ride back down?
SPEAKER_01No. She swims downstream, driven by that ancient instinct, and she encounters the backside of those four massive hydroelectric dams. Without a safe, dedicated downstream passage mechanism, these massive ancient fish are drawn by the flow of the water directly into the intake pipes, and they are pulled through the spinning hydroelectric turbines.
SPEAKER_00That's awful.
SPEAKER_01The mortality rate for large adult eels trying to pass through turbines is devastatingly high. They're simply too long to pass through the blades safely.
SPEAKER_00We took this ancient, perfectly balanced ecological machine, a biological conveyor belt, so reliable that native civilizations built massive stone megastructures to harness it for 6,000 years without depleting it. And we broke it with a concrete wall. We did. And now our best attempt to fix it is putting a band-aid on it with an 18-inch wet ramp and a literal Ford pickup truck.
SPEAKER_01It's pretty humbling.
SPEAKER_00And even then it's only a half measure because we haven't figured out how to get the adult safely back out to the ocean to actually complete the cycle.
SPEAKER_01It underscores the immense humbling difficulty of trying to replicate complex, natural ecological processes with human engineering.
SPEAKER_00Yeah, we can't do it as well as nature does.
SPEAKER_01We are learning, and the eel way is a vital, necessary stopgap to keep the muscles alive and the water clean, but it highlights a fundamental truth of conservation. It is infinitely easier to sever an ecological connection than it is to rebuild one.
SPEAKER_00That really brings the massive scale of this story into focus. And that brings us to the end of our deep drive today. Let's briefly tie all these disparate threads together.
SPEAKER_01It's been quite a journey.
SPEAKER_00We started with a high school teacher looking at Google Earth and finding 6,000-year-old stone V's hiding in plain sight in the Susquehanna River, architecture older than the pyramids. Right. We traced the journey of the bizarre, transparent, leaf-shaped drifters catching the Gulf Stream from the Sargasso Sea, transforming into armored slime-coated climbers that can live for 40 years in a Pennsylvania Creek.
SPEAKER_01And we discovered how those fish are the vital, unwitting taxi service for hundred-year-old mussels.
SPEAKER_00That literally clean the drinking water from millions of people and protect the Chesapeake Bay.
SPEAKER_01It is a profound interwoven tapestry. It shows us how multiple generations, multiple entirely different human cultures spanning thousands of years, from the ancient builders of the Sebasticook Weirs to the boys selling eels on the streets of Danville have interacted with and relied upon this one incredible river system.
SPEAKER_00It's amazing.
SPEAKER_01The river is not just a geographical backdrop, it is an active, living participant in human history.
SPEAKER_00So here is my challenge to you, the listener. The next time you are out walking the dog, driving over a bridge, or just looking out the window at your local rivers, creeks, or landscapes.
SPEAKER_01Try not to just see them as pretty scenery.
SPEAKER_00Exactly. Try to see them as ancient blueprints. Try to see them as the active ecological engines they are. Think about the invisible architecture resting in the mud and the complex hidden life cycles churning away right under the surface of the water.
SPEAKER_01There is always more to learn from the landscapes we think we know best if we just know how to look.
SPEAKER_00And before we go, I want to leave you with one final provocative thought. It's something that wasn't explicitly answered in the research we looked at today, but it's been bouncing around in my head ever since I read the mechanics of the eel's final journey.
SPEAKER_01Oh, I like this one.
SPEAKER_00We talked about how the adult female American eel absorbs her own digestive tract because her body knows she's on a one-way trip, that she will die after spawning. But think about the navigation of that trip for a second. Think about an animal that hatches in the ocean, drifts as a leaf, and then spends up to 40 years completely isolated in a freshwater river in Pennsylvania.
SPEAKER_01All alone.
SPEAKER_00She has no parents to teach her the route, she has no map. Yet, after almost half a century in the mud of a creek, she somehow knows exactly how to navigate thousands of miles back down the river, out into the massive Atlantic Ocean, to find one specific, shifting, floating patch of seaweed exactly where she was born. How does she do it? How? What if memory isn't just something we acquire through experience during our lives? What if memory is something structurally encoded, physically written deep within our varied DNA, waiting half a century to be unlocked? Something to think about the next time you look out over the water, and notice the geometric shapes hidden in the river stones.