It survived for millennia – until humans dammed up its home waters
Imagine paddling along in a kayak on the Missouri River when suddenly a dinosaur swims by below, almost as long as your paddle! That’s not a scene from the upcoming Jurassic World – it was once a reality in thousands of river miles of the Missouri and Mississippi River basins. The ancient pallid sturgeon, whose ancestors date from the time of the dinosaurs, once lived from Great Falls, Montana to New Orleans, Louisiana. But you’d be fortunate to ever see one today; the last wild-born pallid sturgeon are nearing extinction. After having survived 78 million years, they are now close to joining their fossilized ancestors. The situation for the pallid sturgeon is so dire, the U.S. Fish and Wildlife Service (FWS) has resorted to releasing hatchery raised sturgeon, a form of short-term emergency life support.
The appropriately nicknamed “living dinosaur” has silver bony plates instead of scales, can live longer than 50 years, can reach 6 feet long, and can weigh in at about 80 pounds. Their closest living relative, the shovelnose sturgeon, is one tenth their size at a meager eight pounds. The pallid sturgeon is native to the murky Missouri and Mississippi Rivers and their tributaries, where its long, flat, toothless snout is the perfect shape to gobble up smaller fish and other prey it finds on the river floor. They thrive along the bottoms of large sediment-laden rivers, where the natural warm flows create various channels and sand bars.
For generations, pallid sturgeon swam freely in their home rivers. But as humans built dams for flood control, irrigation, navigation, and other uses during the early and mid 1900s, the rivers’ natural sediment, flow and temperature were disrupted, destroying much of the pallid sturgeon’s habitat and blocking the fish from swimming up and downstream. It turns out that pallid sturgeon larvae-as baby sturgeon are called- also need hundreds of miles of free flowing, oxygen-rich waters to survive. When dams break up these long reaches of river, the young larvae (which cannot swim independently) drift into the backwaters of reservoirs, where they sink to the bottom of oxygen-deprived stagnant water and suffocate. A new scientific study released a few weeks ago showed how the dams are at the root of the problem for the pallid sturgeon’s survival.
The largest identified wild population of pallid sturgeon left in the wild is in Montana and western North Dakota, in the Missouri and Yellowstone Rivers. But this population has dwindled to fewer than 125, almost all nearing the end of their lifespans. There has been no evidence of a pallid sturgeon born in the wild surviving to adulthood for several decades. Time is of the essence –the pallid sturgeon cannot afford to continue losing their young to these hazardous dams. The way these dams prevent the pallid sturgeon from successfully reproducing is the riparian equivalent to continuously chopping down trees with eagle nests – the species just can’t stand up to that level of destruction.
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Two Dams, Two Problems for the Pallid
The Intake Diversion Dam on the Yellowstone River (a major tributary of the upper Missouri River), is a 12-foot-high timber and rock barrier that blocks the pallid sturgeon from reaching 165 miles of prime spawning habitat. Unable to get where they need to go, in most years the fish are forced to reproduce in the lower Yellowstone River below Intake Dam instead. But if they spawn there, the young larvae are too close to the next downstream reservoir, Lake Sakakawea, where they are likely to suffocate, starve, or get eaten by predators. Unless the adult fish are able to spawn farther up the Yellowstone, the young are doomed.
FWS urged the Bureau of Reclamation to consider the negative impacts the dam has on pallid sturgeon 23 years ago, but despite the clear problem, the Bureau has never created a way for the fish to bypass the dam and access the critical spawning habitat upstream. Every few years when runoff is high, the sturgeon are able to navigate on their own through a natural sidechannel around the dam. Last spring, five pallid sturgeon used this natural passageway around the dam to swim upstream – and one may have successfully spawned. Now the Bureau and the U.S. Army Corps of Engineers claim to have a plan to improve passage around the dam, but it involves building a higher concrete dam that will best serve irrigation, and includes a fish passage as a secondary goal. It will also block the one channel that sturgeon are known to have used in the past. Many experts are concerned that the proposed “fish ladder” may not work for sturgeon, who are notoriously reluctant to use them at all.
Another longstanding problem comes in the form of Fort Peck Dam on the mainstem Missouri River. In this case, the Corps is ignoring its legal obligation to modify the dam’s operations while pallid sturgeon struggle to survive. The dam releases water that’s far too cold and clear, which destroys the pallid sturgeon’s spawning and rearing habitat. The Corps has refused to modify these flows or increase water temperatures to improve the pallid sturgeon’s chances of reproducing in the wild – something any species must be able to do in order to survive.
To protect this living dinosaur fish from extinction, Defenders filed suit against the U.S. Bureau of Reclamation, the U.S. Army Corps of Engineers (Corps), and the U.S. Fish and Wildlife Service (FWS) under the Endangered Species Act (ESA). These agencies are responsible for finding solutions to help the species survive, even if it means changing how the dams operate. Instead, these two dams on the Missouri and Yellowstone rivers are causing the decline of the largest known population of wild endangered pallid sturgeon.
If the dams continue their “business as usual” operations, it will likely be impossible for the upper Missouri River basin population of pallid sturgeon to spawn and reproduce, keeping the species on the brink of extinction. Yet there are solutions and improvements the agencies can make to change the problems that have been perpetuated for over 20 years. By taking the issue to court, we hope to spur the agencies into action, and give pallid sturgeon the right of way they deserve in their home rivers. This species survived one of the largest mass extinctions the planet has ever seen. Humans have no right to snuff it out now.