PS 25-111 - Population trends of four ray species along the Georgia coast from 2003-2015

Tuesday, August 8, 2017
Exhibit Hall, Oregon Convention Center
Margaret C. Wheat, Department of Natural Sciences, College of Coastal Georgia, Brunswick, GA, David J. Stasek, Department of Biology, College of Coastal Georgia, Brunswick, GA, Patrick J. Geer, Coastal Resources Division, Georgia Department of Natural Resources, Brunswick, GA and Lindsey Aubart, Coastal Resources Division, Department of Natural Resources, Brunswick, GA

The coast of Georgia is home to a wide variety of ecologically and economically important species. Rays are common bycatch species in many commercial fisheries but are presently of little commercial value in Georgia. There are four common species of ray found along the Georgia coast: the Atlantic stingray (Dasayatis sabina), the southern stingray (Dasayatis americana), the bluntnose stingray (Dasayatis say), and the cownose ray (Rhinoptera bonasus). These species have home ranges that extend along the eastern coast of North America with each species making seasonal migrations along the coast. All four species spawn in coastal Georgia waters from April to August. While often caught as bycatch, little is known about the spatial and temporal distributions of ray species along the Georgia coast. The Georgia Department of Natural Resources has conducted a monthly trawl survey at 12 offshore and 24 estuarine sites along the Georgia coast since 1976 and an additional 6 estuarine sites were added in 2003. The number of each species collected at each site was recorded along with the temperature, salinity, and dissolved oxygen of the water. We determined which abiotic factors affected ray abundances and distributions from this survey for the years 2003 to 2015.


The abundance of each ray species was not predicted by abiotic factors, including water parameters, year, month, and/or site location. Populations of the southern stingray, Atlantic stingray, and cownose ray significantly increased between the years of 2007-2010. The abundance of all four species increased during the spawning season from April-August of each year, but this relationship was not significant. Ongoing research is investigating the relationship between ray abundance and the benthic invertebrates that they prey upon. Our results demonstrate that ray populations are healthy along the Georgia coast. This project provides baseline data that will allow managers to detect future population changes.