July 26, 2012
Atlantic Sturgeon at Gray's Reef
Eight endangered Atlantic sturgeon have been detected by acoustic receivers deployed at Gray's Reef
National Marine Sanctuary.
The first sturgeon was detected in the sanctuary by the receivers just over a year ago. The sturgeon count now includes one fish that was originally tagged in the New York Bight by Keith Dunton with Stony Brook University; three tagged in Delaware by Dr. Dewayne Fox with Delaware State University; three tagged in Edisto, S.C. by Bill Post with South Carolina Department of Natural Resources; and one tagged in the Altamaha River by Daniel Erickson, previously with University of Miami Pew Institute for Ocean Science and now with the Oregon Department of Fish and Wildlife and Dr. Douglas Peterson, with the School of Forest Resources at the University of Georgia.
Endangered Atlantic Sturgeon.
(Photo: NOAA Fisheries)
Atlantic sturgeon are large (they can grow to 14 feet long and weigh 500 pounds), slow-growing,
late-maturing, long-lived, estuary-dependent fish that live the majority of their lives in saltwater,
but hatch and spawn in freshwater.
As a species, Atlantic sturgeons face many challenges to their survival. Sturgeon numbers have plummeted by as much as 99 percent in some areas of the East Coast, according to NOAA. On April 6, five distinct population segments of Atlantic sturgeon were protected under the Endangered Species Act. The Chesapeake Bay, New York Bight, Carolina, and South Atlantic populations of Atlantic sturgeon will be listed as endangered, while the Gulf of Maine population will be listed as threatened.
What the sturgeon are doing in Gray's Reef National Marine Sanctuary is not yet clear. But detecting eight individuals, many tagged north of Cape Hatteras, is remarkable because acoustic tagging projects generally have a much smaller sample size than conventional tagging, and the population of Atlantic sturgeon for tagging is quite small. It is also noteworthy that Atlantic sturgeons have never been previously reported from Gray's Reef, in spite of many thousands of man-hours of SCUBA dives and recreational fishing conducted there annually.
Some of the threats to sturgeon include shrinking freshwater wetlands, poor water quality, low oxygen levels and silt in their riverine nursery grounds. Juvenile sturgeon spend the first two to three years in the river in which they are born and they are intolerant of saltwater during that time, according to Dewayne Fox, Assistant Professor of Fisheries at Delaware State University. Increasing silt and salinity in rivers are ongoing threat to sturgeon survival, Fox said.
The receivers that detected the sturgeon are part of an ongoing fish tagging project at Gray's Reef. An array of 21 recievers is deployed throughout the sanctuary and 41 fish that have been internally tagged by Gray's Reef including gag grouper, scamp and red snapper. The Gray's Reef fish tagging project is looking how these reef fish use the sanctuary habitat. The same company that makes tags used by the sanctuary makes tags used by several researchers studying sturgeon and other fish. So the Gray's Reef receivers can pick up "pings" from other tags that are not immediately identifiable by Gray's Reef researchers.
Gray's Reef scientists were able to identify these sturgeon visitors because of a cooperative effort to bring together researchers using acoustic telemetry to study fish movement. As researchers began utilizing acoustic telemetry technology more extensively along the eastern coast of the United States, the potential benefits of collaborating in order to share telemetry data from existing arrays beyond those in their own system became apparent. In response to this, a community of researchers was created to coordinate on the identification of detections of tagged organisms. Now, over 65 researchers from Maine to Florida participate in the Acoustic Cooperative Telemetry group (ACT). Currently there are over 5000 known transmitters deployed since 2004, with over 1000 deployed in 2010 alone. This corresponds to 49 identified species currently being studied along the east coast.
Based on these preliminary observations, it appears that Gray's Reef and other "live-bottom" reefs are an important habitat for Atlantic sturgeon, and they travel great distances to get there.
The Endangered Species Act includes a prohibition against "take," which includes harassing, harming, pursuing, wounding, killing, trapping, capturing, or collecting listed species. Gray's Reef will undertake outreach efforts to fishermen and divers who use Gray's Reef to alert those encountering this endangered species.
For more information on Atlantic sturgeon and those who study them:
NOAA National Marine Fisheries Service Species of Concern
NOAA Fisheries Office of Protected Resources
NOAA Fisheries Service Southeast Regional Office
NOAA Fisheries Service
Delaware State University - Aquatic Sciences