UGA to study endangered Atlantic sturgeon in three Georgia rivers

Peterson, Doug Altamaha River with sturgeon-h.photo

October 8, 2014

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Doug Peterson

Doug Peterson

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  • magnify Peterson, Doug Altamaha River with sturgeon-h.photo

    Doug Peterson, right, of the University of Georgia and his graduate student, Paul Schueller, capture an adult Atlantic sturgeon on the Altamaha River in Georgia as part of their ongoing studies of the species ecology and population dynamics.

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Athens, Ga. - University of Georgia researcher Doug Peterson will use a nearly $500,000 grant from the National Marine Fisheries Service in partnership with the Georgia Department of Natural Resources to determine how well Atlantic sturgeon are reproducing in Georgia rivers two years after the species was listed as endangered.

Biologists feared the fish's populations had been lost from several of the state's coastal waterways.

Populations of the ancient fish appear to be rebounding in some parts of the country, spurring discussion about whether the Atlantic sturgeon should be down listed from endangered status, said Peterson, a fisheries professor in UGA's Warnell School of Forestry and Natural Resources. However, there is no real evidence that the sturgeon is rebounding everywhere, particularly in the South Atlantic Distinct Population Segment, which includes Georgia.

Peterson is launching a three-year project to study the issue.

"Although we've seen a significant increase in juvenile abundance in the Altamaha River, we remain very concerned about populations in the St. Mary's, Satilla and Ogeechee rivers," Peterson said.

Peterson has shown in an unrelated project that the Atlantic sturgeon appears to be rebounding in Georgia. For the first time in decades, he documented sturgeon reproduction in the St. Mary's River.

"We thought they were extinct there," Peterson said, but earlier this year, while working on a new project for the U.S. Navy, his research team captured more than 10 young juveniles he believes were born in the St. Mary's River.

"Because Atlantic sturgeon return to spawn only in the same river where they were born, this was a significant and exciting find," Peterson said.

Atlantic sturgeon, targeted for their valuable caviar, were first protected from commercial fishing in 1996 after studies showed their numbers had declined dramatically, pushing them to the brink of extinction. The National Marine Fisheries Service listed them as an endangered species in 2012, but that decision has been controversial and unpopular, Peterson said, because of the strict rules in place that commercial fisheries must follow if one is accidentally caught in a net and because of the detailed management plans state agencies must enact to deal with situations involving the Atlantic sturgeon bycatch.

Initial recommendations from sturgeon biologists was to list the Atlantic sturgeon as "threatened," which would have provided similar protections with fewer restrictions on local fisheries. Further complicating this controversy was the National Marine Fisheries Service's decision to list some populations of Atlantic sturgeon as endangered while listing others as threatened.

The imperiled fish are found along the east coast as far as Canada, but only those populations south of Maine are considered endangered.

Peterson's project will focus on the Ogeechee, Satilla and Altamaha rivers because these three Georgia waterways are considered the "barometer of recovery," Peterson said. "Together, they comprise the southernmost portion of the Atlantic sturgeon's range. These rivers are essentially the canaries in the mine. If sturgeon are recovering here, then they're likely recovering in other rivers as well."

The project has three primary objectives, the first of which is to find out how many sturgeon are being born in the Ogeechee and Satilla rivers. Populations in these two rivers have been particularly low, while those in the Altamaha appear to have recovered.

Peterson also will compare the quality of juvenile nursery habitats in the Ogeechee and Satilla rivers to those of the Altamaha.

"By estimating the number of 1-year-old sturgeon in any given river, we can get a really good idea of how the population is doing," Peterson said.

The Altamaha River population has had a tremendous resurgence in recent years, growing from less than a thousand of these young juveniles in 2004 to nearly 7,000 in 2012. By comparing how the year-old sturgeon in the Ogeechee and Satilla rivers are doing with those in the Altamaha, Peterson can determine if there is something about the nursery habitats in those other rivers that could be limiting recovery of their population.

Peterson plans to tag some of the year-old sturgeon he catches with acoustic "pingers" that will allow his team to track where they go, when they go there and for how long. "We're sort of like detectives trying to unravel a mystery about why these ancient fish are recovering in some rivers and not others." Peterson said.

One of the most complex parts of the project involves DNA "fingerprinting" of the sturgeon. Scientists have already developed a DNA library for sturgeon, which they use to monitor the health of each population, but there could be some major flaws in the system. The library allows fishery managers to determine the population of origin for each individual sturgeon accidentally captured in commercial fisheries nets—important because by listing the species as "endangered," states and commercial fisheries could run afoul of the Endangered Species Act if Atlantic sturgeon are accidentally caught in their nets.

Checking the DNA library would allow scientists to determine which fisheries are harming sturgeon recovery the most, especially as not every sturgeon population is affected by the fisheries business.

"Unfortunately, that DNA library may be corrupted because it was mostly constructed using tissue samples from adult sturgeon," he said. "This could be a problem because adult sturgeon often move around and are frequently found in non-natal rivers. That means that they could be misidentified in the genetic database as being from one population when they are actually from another."

Peterson's project plans to take samples from juvenile sturgeon before they leave their natal rivers to help correct these potential errors in the genetic database. Ultimately, Peterson said, the results of this project should help improve the quality of the genetic database for the species.

"No one wants to shut down our otherwise well-managed commercial fisheries," he said. "The key is to develop the best tools possible that will help managers minimize the effects that these fisheries are having on Atlantic sturgeon recovery."

Peterson is working on the project with Isaac Wirgin, associate professor in the Department of Environmental Medicine at New York University School of Medicine. Wirgin, a well-known sturgeon genetics expert, will analyze the DNA samples Peterson takes from sturgeon that his team captures in Georgia's rivers. Peterson will receive $466,687 from the National Marine Fisheries Service for the study in partnership with the Georgia Department of Natural Resources and will subcontract to Wirgin for $87,744 to conduct the DNA analyses.

For more information on the Warnell School of Forestry and Natural Resources, see http://warnell.uga.edu/.

 

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