Alabama Scientists Use e-DNA to Discover Signs of Sturgeon Presumed Extinct
Alabama Sturgeon by Debbie Kay
Alabama Scientists are having a real soap opera moment, as one of their indigenous species of fish, presumed extinct, may have been found alive. The Alabama sturgeon is considered one of the rarest freshwater fish on the planet, and has not been seen alive since 2007. However, scientists doing work in its home range of the Mobile Basin have now found evidence that it continues, elusively, to live in the area through recent environmental DNA sample collections.
About the Alabama Sturgeon
The Alabama sturgeon, Scaphirhynchus suttkusi, is a small, yellow-orange species of sturgeon that lives exclusively in the Mobile Basin of the Alabama River. It grows to about 30 inches in size, and lives 12 to 20 years. In 1993, the state and federal protection program for the once-populous Alabama sturgeon began. This species had evaded identification until 1991, and were once believed to be the young of the more common gulf sturgeon. By the time the fish were shown to be genetically unique, their numbers had declined so much due to the impacts of several dams in the watershed that there was a question whether any effort at all could save them. Since protection efforts were considered to be a large and expensive change for much of the river’s industries, there was a battle between the businesses and environmentalists whether to take protection measures at all.
Protection was difficult to verify, as only three individual sturgeon were actually captured and held in hand within ten years. The last known fish, a male, was tagged in 2006 with a radio tracker, with the hopes that it would lead scientists to a larger breeding population. Unfortunately, that did not happen before the transmitter died in 2007.
Scientists recently collected 130 environmental DNA samples along the length of the Alabama River and found that approximately 17 percent of the samples had Alabama sturgeon DNA. This means that the fish were in the area within the past 8 to 40 days, based on the average rate of DNA breakdown in the area. This means the fish is present, but it has not been seen.
As these locations are narrowed down, scientists plan to do more extensive surveys on the areas that get continued “hits” during eDNA sampling. Fish collection/viewing can be done via snorkeling, dewatering, or backpack electrofishing. If they find fish in any number, this may be an opportunity There is currently a hatchery-assisted breeding plan for the Alabama sturgeon that sits on the law books if the state manages to locate and secure some breeding pairs of fish. To locate a pair (or hopefully more than one) would allow an opportunity to begin adding fish to more areas, and to better study individuals to understand the specific environmental factors they need to thrive. This can lead to smarter management decisions in the future to truly bring this elusive fish species its heroic return from the dead.