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Marine Turtle Newsletter 161:19-21, © 2020

Marine Turtle Newsletter-Online

Key to Living Tags for Northwestern Atlantic Loggerhead Turtles (Caretta caretta)

Emily Turla & Jeanette Wyneken
FAU Marine Research Laboratory, Florida Atlantic University, Boca Raton, FL, 33431, USA (E-mail: eturla2013@fau.edu, jwyneken@fau.edu)

Living tags are one of several mark-recapture methods used to identify sea turtles (Henderickson & Henderickson 1980; Schwartz 1981; Balazs 1985; Rowe & Kelly 2005; Dutton & Stewart 2013; Limpus et al. 2019). Living tags are a kind of xenograft, meaning that the graft and host are from the same individual. The reciprocal xenografting procedure involves excising and transplanting a small piece of scute and living epidermis between selected carapace and plastron scutes (Henderickson & Henderickson 1980). The tissue grafts provide a permanent specific pattern to identify the particular year-class of turtles. The living tags are strips of tissue fully contained within a single carapacial scute and a single plastron scute for each year-class and should be distinctive from barnacle scars. Once grafted, the carapace tag is yellow to white and the plastron tag is brown to tan. The plastron tag tissue tends to spread slightly so may fade with age and as the turtle grows. Occasionally the transplanted tissue is rejected and dies, and the site does not leave a clear scar. Consequently, a few turtles may have just a single tag. The Florida Atlantic University Marine Research Laboratory has systematically tagged small juvenile Northwestern Atlantic loggerhead sea turtles (Caretta caretta) from 2003 - 2004 and 2009 - 2019. Each year-class has a distinctive living tag pattern on the carapace and plastron (Fig. 1). In 2003 and 2004, loggerheads received different living tag patterns to distinguish between turtles that hatched on Florida’s east and west coasts. East coast turtles in 2003 were further distinguished into northern and southern (peninsular Florida) subpopulations with different plastron tag locations. The procedure of using different patterns to distinguish coasts was abandoned after 2004, so that in all other years (2009 - 2019) all loggerheads from the same year-class received the same living tag pattern. Fig. 2 shows an example of a turtle from the 2017 year-class at the time that the living tags were applied and the same turtle two years later.

All turtles were released into the Northwest Atlantic offshore, except for a few turtles that were retained by local environmental education facilities. These turtles are released coastally after reaching a standard carapace length of at least 45 cm. We expect that, at the time of publication, turtles may be old enough to be recognized in live captures, sightings, or if health status becomes compromised, as strandings. All turtles were photographed immediately prior to release for the purpose of future identification. The goal of identifying the turtles observed with living tags is to better understand the ages of turtles that recruit to certain habitats and the length of time between hatching and maturity using verified durations rather than estimates (Mrosovsky & Godfrey 2003). For each turtle released, we have hatch date, location of the nest, growth rate in the lab, sex identification confirmed with laparoscopy, and incubation conditions. We request that anyone who sees a loggerhead with a living tag please contact us and please send clear photos of the carapace, plastron, and dorsal and lateral head if possible. Contact information: (wynekenatwork@gmail.com or jwyneken@fau.edu) and copy information to current stranding coordinators.

Acknowledgements. This work was conducted with permission from Florida Fish and Wildlife Conservation Commission under MTP-073. We thank the several lab technicians who contributed to this database of tagged turtles including L. Bachler, C. Gonzalez, A. Lolavar, L. Stokes, M. Young, J. Vaughn, and M. Warraich.

BALAZS, G.H. 1985. Retention of flipper tags on hatchling sea turtles. Herpetological Review 6: 43-45.

DUTTON, P.H. & K.R. STEWART. 2013. A method for sampling hatchling sea turtles for the development of a genetic tag. Marine Turtle Newsletter 138:3-7.

HENDRICKSON, J.R. & L.P. HENDRICKSON. 1980. “Living tags” for sea turtles. National Marine Fisheries Service, Southwest Fisheries Science Center Administrative Report H-80-17C (Contract #80-ABH-00062), Honolulu, Hawaii. 27 pp.

LIMPUS, C.J., J. FERGUSON, N.N. FITZSIMMONS, D.J. LIMPUS & J.M. SERGEEV. 2019. Recommencing the tagging of flatback turtle, Natator depressus, hatchlings using carapace notching. Marine Turtle Newsletter 157:1-4.

MROSOVSKY, N. & M.H. GODFREY. 2003. EDITORIAL: Living tag, living reputation. Marine Turtle Newsletter 99:3-4.

ROWE, C.L. & S.M. KELLY. 2005. Marking hatchling turtles via intraperitoneal placement of PIT tags: implications for long- term studies. Herpetological Review 36: 408-410.

SCHWARTZ, F.J. 1981. A long-term internal tag for sea turtles. Northeast Gulf Science 5: 87-93.


Figure 1. Living tag patterns for each year-class. Small strips of tissue from the carapace and plastron were reciprocally transplanted in a particular pattern for each year-class. This figure includes patterns for future years.


Figure 2. (Top) Carapace and plastron of a loggerhead from the 2017 year-class immediately after receiving living tags. (Bottom) Carapace and plastron of the same turtle two years later. This loggerhead was transferred to an environmental education center until his release in coastal waters. Photo credit: Samantha Arner, Conservancy of Southwest Florida, Naples, FL.