MTN 149:12-13 Tag Returns of Adult Green Turtles from Florida’s Headstart Program (1971-1988)

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Tag Returns of Adult Green Turtles from Florida’s Headstart Program (1971-1988)

Carrie L. Keske¹, Dean A. Bagley^1,2, Anne B. Meylan³, Cody R. Mott¹, Michael J. Bresette¹, Llewellyn M. Ehrhart^1,2 & Katherine L. Mansfield²
¹ Inwater Research Group Inc., 4160 NE Hyline Dr., Jensen Beach, Florida 34957, USA
(E-mail: ckeske@inwater.org; cmott@inwater.org; mbresette@inwater.org);
² Department of Biology, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA (E-mail: dean.bagley@ucf.edu; lmehrhart@att.net; kate.mansfied@ucf.edu);
³Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 100 8th Avenue Southeast, St. Petersburg, FL 33701, USA (E-mail: anne.meylan@myfwc.com)

From 1971 to 1988, the Florida Department of Natural Resources (FDNR, now Florida Fish and Wildlife Conservation Commission) conducted an experimental headstart program for Florida green turtles (Chelonia mydas). The program was initiated by Ross Witham prior to any organized statewide sea turtle nesting beach surveys, at a time when green turtle nest totals in the state were unknown. The first statewide nesting data were not collected until 1979 and those surveys indicated a total of 62 green turtle nests for that year (Meylan et al. 1995). Witham theorized that by raising green turtles in captivity and releasing them at a larger size, the high initial mortality rate associated with predation could be offset (Huff 1989). The hope was that the turtles that received a headstart would return to Florida beaches to nest and lead to an increase in the green turtle nesting population in Florida.

Clutches of green turtle eggs were collected from beaches on the central to southeast coast of Florida and incubated in Styrofoam® coolers at FDNR’s field office in Jensen Beach, Florida. Once hatched, green turtles were reared at various facilities around the state for up to a year before being tagged and released. This program was initiated before temperature-dependent sex determination was clearly understood, and there were concerns in later years that the headstarted turtles may have been incubated at temperatures predicted to produce only males (Huff 1989). These concerns and the lack of any evidence that headstarted turtles came back to nest on Florida beaches led to the termination of the program in 1988.

Throughout the course of the headstart program, there were over 18,000 green turtle hatchlings reared for tagging and release (Huff 1989). The size range of most of these turtles at release was 16.0 cm - 35.0 cm (SCL - Straight Carapace Length, notch-to-tip). All were flipper-tagged with a single Monel or Inconel tag (National Band and Tag Co., Newport, Kentucky, Style No. 1005, Size No. 49 and Style No. 41005, Size No. 681) (Witham & Futch 1977). Most turtles were released on the beach; however, near the end of the project, some were released at sea or in coastal lagoons.

Table 1. Headstarted turtle release and tag recovery information for green turtles (Chelonia mydas) recovered as adults in Florida.

Identified by their original flipper tags, six headstarted green turtles have been observed in Florida waters or on beaches as adults since the termination of the program (Table 1). The first (PPG413) was a 91.7 cm SCL male (tail length = 39.0 cm) captured in 2002 at the St. Lucie Nuclear Power Plant intake canal on Hutchinson Island, Florida. The second (PPV502) was a female found in August 2002 nesting in the Archie Carr National Wildlife Refuge (ACNWR) in Melbourne Beach, Florida, during nesting surveys conducted by the University of Central Florida (UCF). This turtle was encountered again, nesting on the same beach in August, 2014. Three other headstarted females were encountered by UCF on the ACNWR beach - in 2005, 2008 and 2012. Two of these, PPG346 and PPN642, did not lay eggs and their activities were recorded as non-nesting emergences. Female turtle PPG637 nested successfully in June of 2012. In 2008, a headstarted adult male was found by UCF when a green turtle mating pair washed up on the beach long enough for the tag number to be documented. All six turtles hatched between 1985 and 1987, and were released between 1986 and 1988. Four of the six were released offshore, rather than from the beach. Females subsequently encountered on the nesting beach were between 15 and 24 years of age.

The recaptures reported here provide evidence that at least some of the 18,000 turtles reared as part of Florida’s green turtle headstart program survived to reach reproductive maturity. Tag loss (Reisser et al. 2008; McNeill et al. 2013), the use of a single tag at release, the small number of nighttime surveys and tagging projects during green turtle nesting season on Florida beaches, and the generally lower probability of seeing males, likely contributed to the low (0.03%) rate of recapture. However, the extent to which these factors influenced the recapture rate is unknown. In any case, the data reported here are too few to offer insight regarding the success or failure of the headstarting project. The practice of headstarting sea turtles was terminated in Florida in 1988 and is now not allowed under Florida’s Administrative Code Rule 68E-1.

Acknowledgements. We extend our appreciation to Peter Eliazar of the Archie Carr Center for Sea Turtle Research for his role in coordinating the tag return information reported from both the University of Central Florida Marine Turtle Research Group (UCFMTRG) and Inwater Research Group (IRG). We also recognize and thank the following students and personnel of UCFMTRG for their data collection: Stacy Kubis (Hargrove), Kelly Borrowman, Tonya Estevez, Donya Saunders, Alexis Koesters, Liz Bouleris, Camille Brescacin (Collins), Janet Hochella, Jim Stevenson, Jennifer Elliott and Andrew Sterner. Thanks also to Rick Herren of IRG who assisted in the capture of the male at the St. Lucie Nuclear Power Plant.

HUFF, J.A. 1989. Florida (USA) terminates headstart program. Marine Turtle Newsletter 46:1-2.

MCNEILL, J.B., A.M. SCHUELLER, L. AVENS, A.G. HALL, L.R. GOSHE & S.P. EPPERLY. 2013. Estimates of tag loss for loggerhead sea turtles (Caretta caretta) in the western north Atlantic. Herpetological Review 44: 221-226.

MEYLAN, A., B. SCHROEDER & A. MOSIER. 1995. Sea turtle nesting activity in the State of Florida 1979-1992. Florida Marine Research Publications 52: 1-51.

REISSER, J., M. PROIETTI, P. KINAS & I. SAZIMA. 2008. Photographic identification of sea turtles: method of description and validation, with an estimation of tag loss. Endangered Species Research 5: 73-82.

WITHAM, R. & C.R. FUTCH. 1977. Early growth and oceanic survival of pen-reared sea turtles. Herpetologica 33: 404-409.