Using Acoustic Telemetry to Track Cobia Movement Patterns

Researchers track the movements of cobia (Rachycentron canadum) to determine migration patterns and the geographical location of the biological Atlantic and Gulf stock boundary.

Why are we doing this project?

Tagged Cobia graphic

Cobia is a popular saltwater recreational fishery in the southeastern U.S. due to ease of access, brute fighting strength, and excellent culinary qualities. Currently, cobia are managed as two stocks by the Gulf and South Atlantic Fishery Management Councils, with separate regulations for each stock. New scientific evidence presented in 2012 suggested that the stock boundary was somewhere between Port St. Lucie, Florida and Hilton Head, South Carolina; not at the Florida Keys as previously thought. Currently, cobia are assessed by the Florida/Georgia line. However, more specific information is needed on how much movement occurs between the stocks, including how separate the stocks are and in what area do they separate. For this reason, FWRI is working with scientists in northern Florida, Georgia, and South Carolina to deploy tags above and below the current management line. Movement data, like what is being gathered in this project, will help inform mangers and support efficient regulations to maintain healthy stocks of cobia for generations to come.

How we tag cobia

Funding for this project is provided by NOAA’s Cooperative Research Program, where the public works alongside scientists to answer questions about our fisheries. FWRI scientists accompany local charter boat captains targeting cobia in coastal waters. Cobia are caught by rod and reel and brought to the boat where they are assessed for good health. Juveniles may exhibit different migratory patterns than adults, so only adults are selected for tagging. To implant the tag, a small incision is made on the belly and an acoustic transmitter, about the size of a double A battery, is inserted into the belly cavity. A suture closes the incision. In addition to the acoustic tag, fish are tagged with two conventional dart tags near the dorsal fin and measured before being released. This method of tag implementation has been used successfully for many species of fish, including Common Snook.

The acoustic tag transmits a unique code every 120 seconds that can only be detected by an underwater piece of equipment called a receiver. The receiver can hear a tag up to a half-kilometer away. When a tagged fish swims in proximity to a receiver, the unique code, date and time are recorded on the receiver. Scientists download the receivers every few months and discover which tagged fish have been in the area.

Acoustic transmitter Incision for transmitter Dart tags in cobia Release of tagged cobia
       

How we track cobia

The FWRI Tequesta field lab maintains 60 receivers along the Florida Atlantic coast from Palm Beach Inlet to Sebastian Inlet. However, cobia are expected to migrate much farther north and south. By collaborating with scientists in the Florida Atlantic Coast Telemetry (FACT) network, FWRI scientists can track tagged cobia north to New York, or southwest into the Gulf of Mexico.

The FACT network is a collaboration of over two dozen marine research organizations using passive acoustic technology to resolve the life history strategies of fishes and sea turtles in the U.S. South Atlantic, the Bahamas, and Caribbean. Conceived in 2008 as a means of tracking coastal fish and sea turtles in east-central Florida, the FACT array has expanded rapidly in geographic scope and membership, and now includes state and federal wildlife agencies, universities, non-profit and private marine research organizations. As tagged animals disperse from a researcher’s core study area, they are often detected by other members, allowing animal movement to be tracked over greater distances and for longer periods than would otherwise be possible. And since many coastal species, including cobia, have been proven highly migratory, researchers also coordinate with other regional acoustic telemetry arrays including the ACT network in the U.S. mid-Atlantic and iTAG group in the Gulf of Mexico.

If you are using telemetry technology and would like to join FACT, or for more information, email Joy Young.

Diagram showing how acoustic telemetry works underwater

















Citizen Science

  • If you catch a tagged cobia please do not harvest it!
    • Record the tag number, fork length, date and general location of catch.
    • Release the fish in good condition with tags still intact.
    • Call 888-824-7472 to report the cobia and get a t-shirt.
    • Releasing tagged cobia will allow them to continue gathering valuable data.
  • For the purpose of this study, we discourage the harvest of tagged cobia.
    If you accidentally harvest a tagged cobia:
    • Report all information listed above
    • Return BOTH the internal acoustic transmitter AND plastic dart tags to:

      Attn: Jim Whittington
      Florida Fish and Wildlife Conservation Commission
      Tequesta Field Laboratory
      19100 SE Federal Hwy.
      Tequesta, FL 3346

    • The internal acoustic transmitter can be found implanted just inside the body cavity on the underside of the fish. This will provide valuable information to researchers.
  • Anglers can also assist in this project by collecting fin clips from cobia caught on the east coast of Florida. Email Jim.Whittington@MyFWC.com or call 561-882-5975 to request a fin clip kit.
  • Please observe all fishing regulations and license requirements.

Visit our Flickr albumExternal Website to view more photos of how researchers use telemetry to understand cobia genetics and movements.



FWC Facts:
White and brown shrimp depend on estuaries as nursery habitats, leaving when they reach 4-5 inches in length. This “shrimp run” occurs in late summer or early fall.

Learn More at AskFWC