Credit: Emily Jones
Sharks Offer Snapshot Of Coastal Waterways’ Health
Researchers on the Georgia coast are studying sharks as a way to check in on the overall health of the estuary, where coastal streams and rivers meet the ocean. GPB’s Emily Jones rode along with them and produced this postcard.
On a beach, it would be cause for concern. But on this small skiff on the Wassaw Sound near Savannah at the mouth of the Wilmington River, it was a cry of excitement.
A team of researchers was pulling in their line, a long length of rope with 50 baited hooks arrayed along it, and they’d made their first catch of the day: a bonnethead shark, exactly what they were after.
The researchers are studying the sharks as a way to check in on the overall health of the estuary, the bodies of water like this sound where coastal streams and rivers meet the ocean. Water conditions such as salinity and bacteria coupled with measurements of the sharks offer a snapshot of the ecosystem’s overall health.
“Sharks are playing a top predator role in the estuary, so they act as sentinels of health,” said Kady Lyons, a research scientist at the Georgia Aquarium, explaining that poor health in sharks can indicate something is wrong further down in the food web.
“If that can trickle all the way up to the top predators, that really — they can serve as these canaries in the coal mine to suggest that maybe something's out of balance or it's not as healthy as we would hope it to be,” she said.
Lyons is advising Kennesaw State University graduate student Allyson Stiles, who’s conducting the research as part of her master’s thesis. Georgia Southern University is also supporting the project, along with the UGA Marine Extension and Georgia Sea Grant.
During the limited time the sharks could safely stay out of the water, the team acted quickly to weigh each, measure its length and girth, collect a blood sample and small clip from a fin and, if the shark was big enough, attach a tag.
Then they returned the sharks to the water and helped them swim off, and zoomed away to the next research site.
The sharks in this study are mostly small, some less than a foot long. Most are bonnetheads, a smaller member of the hammerhead family, as well as Atlantic sharp nose, blacktip and sandbar sharks.
The species they catch, Lyons said, as well as the number of sharks, add to the helpful data for their research into this important ecosystem.
An earlier version of this story incorrectly stated that the UGA Marine Education Center and Aquarium on Skidaway Island was supporting the study. It's actually supported by the UGA Marine Extension and Georgia Sea Grant.