Adult Red Drum and Shark Longline Survey

The Georgia Department of Natural Resources Coastal Resources Division utilizes a near shore red drum survey which encompasses state and federal waters off the coast of Georgia and northeast Florida.  Current sampling occurs in waters off the Altamaha River drainage in Georgia to the St. Johns River drainage in Florida.  Initiated in 2006, this pilot survey has examined the effects of bait type and hook size on species selectivity as well as examining spatial and temporal effects on catch rates.  The survey also produces abundance estimates for shark species found offshore.

Photo of a red drum being scanned after having a tag inserted in the fish.

Sampling is conducted monthly from April through December.  From April through August, 25 stations are sampled each month in waters off southeast Georgia.  From September through November, 35 stations are sampled each month, 10 of which are in waters off northeast Florida.  Stations are randomly chosen from a subset of sites identified as areas with high encounter probabilities for April through August sampling events.  From September through December, three strata are delineated off Georgia (inshore; near shore; offshore) and sampling efforts are proportionally allocated to match the emigration pattern of adult reds.  Stations sampled off Florida are randomly sampled from sites with high encounter probabilities.  All stations are sampled during daylight hours and are generally located in water depths between 13 and 65 feet.

Photo of the 47 foot Research Vessel Marguerite used to conduct the longline survey.

The longline is deployed from the R/V Marguerite, a 47’ offshore vessel. The mainline is made of 600 lb. monofilament and is approx. ½ nautical mile in length. A total of 60 droplines are attached to the mainline, where each dropline consists of a longline snap, 1.5 ft of 200 lb. monofilament, and a 12/0 circle hook on the terminal end. Hooks are not offset and have barbs depressed. The total soak time is 30 minutes with half of the hooks baited with squid and the other half baited with mullet.  Soak times is 30 minutes in duration, measured from second anchor deployment to first anchor retrieval.

All sharks captured are identified to species, sexed, measured, weighed and examined for umbilical scarring/remains and then tagged.  Atlantic sharpnose sharks are not tagged.  Red drum are measured, weighed, fin clipped, and tagged.  All other specimens are identified and counted.  The survey has been successful at capturing red drum and has caught 14 shark species, four of which are commonly caught in Georgia (Atlantic sharpnose shark, blacknose shark, bonnethead, and blacktip shark).

Photo of two scientists measuring a shark.