Search continues for the Alabama sturgeon, one of the rarest fish on earth

Alabama sturgeon

State fisheries researchers Steve Rider, left and Travis Powell show off the rare Alabama sturgeon they caught in 2004 in the Alabama River. The Alabama sturgeon hasn't been caught in Alabama's rivers since 2007, but DNA evidence shows it's still out there.Alabama Department of Conservation and Natural Resources

This is the first in a series looking at 10 of the most unusual and noteworthy endangered species in Alabama. The state is one of the most biodiverse in the nation, and today there are 131 species on the brink of disappearing.

The Alabama sturgeon is so rare that even biologists who are actively trying to capture it haven’t caught one in more than 12 years.

In fact, the only reason we know the fish still exists is the slimy traces of its genetic material that show up in a new kind of monitoring called E-DNA.

This riverine monster was once a prize for fishermen and fed a caviar industry in Alabama, but today is one of the most endangered fishes on earth.

Where do they live?

The Alabama sturgeon swims upstream to spawn, releasing its larvae to drift downstream as they develop. The sturgeon prefers deep, fast-moving river channels. Decades ago, the sturgeon roamed Alabama’s rivers from the Mobile-Tensaw Delta to the Cahaba, Coosa and Tombigbee Rivers.

For decades, people believed the Alabama sturgeon to be smaller examples of a larger species, the Gulf sturgeon. However, in the 1980s, biologists determined that the Alabama sturgeon was a distinct species based on a handful of specimens that were preserved in museums.

How many are left?

Not many.

E-DNA samples have confirmed at least two areas in Alabama where the fish is still around, but those results can’t tell us how many fish are still alive. They just confirm that somewhere, somehow, the Alabama sturgeon is still swimming.

Alabama sturgeon

ARCHIVED PHOTO-Biologists with the Alabama Wildlife and Freshwater Fisheries and the U.S. Fish and Wildlife Service examine a male Alabama sturgeon found in the Alabama River, April 4, 2007, near Marion, Ala. The biologists weighed, took measurements, determined its sex and placed a sonar transponder into the fish surgically. (The Birmingham News, Joe Songer)Joe Songer

What killed them?

The construction of large hydroelectric dams, along with extensive harvesting for meat and caviar took the biggest tolls on the sturgeon. The three fish that were caught in the 2000s were pulled from the Alabama River, below the Claiborne Dam, which is the first dam blocking the way for fish swimming up from the Mobile-Tensaw Delta.

The sturgeon is not the only species impacted by dam construction, as the dams turned several of Alabama’s free-flowing rivers into massive lakes, completely changing the character of the ecosystems and the habitat those species had evolved to live in.

The U.S. Fish and Wildlife Service estimates that those dams in the Mobile Basin are responsible for roughly half the extinctions in the United States since the 1800s. The dams build on the Coosa River alone are believed to have caused 40 extinctions, including fish, mussels and snails.

Is it too late?

The Alabama Department of Conservation and Natural Resources has been working for at least 15 years to capture live Alabama sturgeons in order to breed them in captivity and release them in areas where they might be able to survive.

So far, even with the help of E-DNA and electroshock fishing, they’ve been unsuccessful. A male Alabama sturgeon caught in 2007 was determined to be infertile and released with a radio transmitter attached. The device stopped transmitting in 2009.

What can we do?

Some other fish species that have been impacted by dams have been able to restore their numbers through fish tunnels in the dams, or deliberate scheduling of the locks during migration times, but the numbers of Alabama sturgeon are so depleted that the population likely needs to rebound before those kinds of efforts would be helpful.

Why should we care?

The Alabama sturgeon is a useful fish for its meat and its caviar, and a key to the river ecosystems of the past. But mostly, bringing the elusive species back from the brink would help restore some of the wildlife that many feared would be lost thanks to the widespread construction of dams in the state.

More about the Alabama sturgeon:

Alabama sturgeon graphic

Alabama sturgeonPhoto by Ala. Dept. of Conservation | Graphic by Ramsey Archibald

More from our series Endangered in Alabama:

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