Six University of Delaware sea turtles released in N.C. untagged

A reader asked if the sea turtles hatched at the University of Delaware last week were to be released with tracking tags. The short answer is no, and we explain why.

We reported in the Feed last week that a newly hatched bale of sea turtles from the University of Delaware’s College of Earth, Ocean and Environment in Lewes were scheduled to make a trip to North Carolina to be released into the ocean.

The release happened last week, and Brian Sulecki, a NewsWorks reader, asked if any of the turtles were tagged for tracking purposes.

We checked with WHYY’s Mark Eichmann, host of First. He got in touch with Suzanne Thurman of the Marine Education, Research and Rehabilitation Institute, and Edna Stetzar, an environmental scientist with the Delaware Department of Natural Resources and Environmental Control.

The short answer is no.

“They will not be tagged due to the difficulty of tagging such a small creature,” said Thurman. “There was, however, genetic testing done so that future nesting turtles from this specific clutch can be identified.”

Stetzar conferred with Dr. Matthew Godfrey of the North Carolina Wildlife Resources Commission. He is the researcher to whom the hatchlings and un-hatched eggs were transferred, and he confirmed that larger individuals are suitable for tagging while hatchlings are too small. “There is no easy method for tagging the hatchlings, and they will be released untagged,” said Stetzar. 

She outlined the most common tagging methods used and the reason they pose a problem with hatchlings:

1. Flipper tags (metal or plastic): Currently there are no tags small enough for hatchlings. Also, tag loss is an issue with any aquatic species that are growing and actively swimming.

2. Passive integrated transponder tags: PIT tags are placed in the body cavity. As the hatchlings grow, the tag would end up deeper into the tissues. After several years have passed, the tag would be too deeply embedded for most scanners to detect.

3. “Living tag”: This is a tissue graft of contrasting pigments. A small patch of tissue is taken from the darker carapace (the turtle shell) and grafted to the lighter plastron (the “belly” of the turtle). As hatchlings grow, this tag may not be easily detected. Also, researchers who find the turtles would have to know to look for the tag, posing a further challenge.

4. Coded wire tags: These tags are simply a small piece of metal inserted into the body tissue. Metal detectors are used to determine their presence, but they yield little additional data unless they are removed and decoded. Again, there can be issues with tag loss.