For over 40 years, staff with the Division of Sea Turtle Science and Recovery have initiated and conducted scientific research on topics related to sea turtle health, conservation, and protection.
Scientific research can reveal information such as foraging habits, migration patterns, habitat use, and determine recovery effort best practices. Equally important, scientific research can drive policy change to protect and conserve sea turtles. These projects began only after in-depth consultation with numerous state and federal government agencies and have been formulated in accordance with federal regulations and Recovery Plans prepared for each sea turtle species, and authorized under federal and state threatened and endangered species permits and institutional animal care and use committee (IACUC) protocols.
Padre Island National Seashore preserves the longest stretch of undeveloped barrier island beach in the United States. Also included within the boundaries of this 130,000-acre park are waters of the nearshore Gulf of Mexico, Mansfield Channel, and Laguna Madre. All five threatened and endangered sea turtle species that occur within the Gulf of Mexico are found at Padre Island National Seashore. The park provides habitat for nesting, transient, and seasonally resident sea turtles. Hence, all life stages, from eggs to adults, are present at different times of the year. Scientific research conducted by the Division of Sea Turtle Science and Recovery involves all five sea turtle species found in the Gulf of Mexico, however, projects are concentrated on Kemp’s ridley and green sea turtles due to their relative abundance within the park compared to other sea turtle species.
Local, state, national, and international partnerships are critical to sea turtle research as sea turtles are highly migratory and their habitats span political boundaries. The research conducted by the Division of Sea Turtle Science and Recovery is part of a global effort to conserve and protect threatened and endangered sea turtle species so they can be enjoyed by future generations. Research conducted by the Division is used to address recovery task priority items in sea turtle recovery plans, improve National Park Service sea turtle management practices, and assess the impacts of the Deepwater Horizon oil spill.
To learn more about our research and international collaborations click the images below, our publications found at those links, and the recent Newswave and US Fish & Wildlife publications from the Department of the Interior.
Satellite Tracking Research
Studying the post-nesting movements of female Kemp’s ridley sea turtles to identify and protect critical ocean corridors
Sea Turtle Egg Examination
Analyzing the effects of incubation temperatures on sex ratios of hatchlings to promote the population growth of Kemp’s ridley sea turtles
Green Sea Turtle Studies
Studying the movements of juvenile green sea turtles to identify and protect the habitat for this threatened species
Several research projects have been conducted or are on-going regarding nesting and stranded sea turtles in Texas. This research is collaborative and involves many partners in the USA and Mexico. Topics that Padre Island National Seashore staff have participated in include:
- Sea turtle mating, nesting, and population modeling (Shaver 1989, 1992, 1995a, 2000; Shaver and Amos 1988; Shaver and Miller 1999; Shaver and Frandsen 2019; Shaver and Streich 2019; Shaver et al. 2005, 2019a, 2019b; Richards et al. 2011; Caillouet et al. 2016a; Gallaway 2016a, 2016b; Rafferty et al. 2019; Culver et al. 2020)
- Kemp’s ridley hatchling distribution and dispersion (Putman et al. 2013; Putman et al. 2020)
- Kemp’s ridley mark recapture tagging (Morreale et al. 2007; Shaver et al. 2016; Schmid et al. 2020)
- Sea turtle age at first nesting and growth rates (Bjorndal et al. 2001; Caillouet et al. 2011; Avens et al. 2017; Bjorndal et al. 2017; Craven et al. 2019)
- Sea turtle genetic studies (Bowen et al. 2004, 2007a, 2007b; Anderson et al. 2013; Frey et al. 2014; Hurtado et al. 2016; Shamblin et al. 2016)
- Trophic levels and foraging ecology of Kemp’s ridley sea turtles (Shaver 1991; Howell et al. 2016; Reich et al. 2017)
- Land-based threats such as coastal development, predation, and tidal inundation (Fuentes et al. 2019, 2020; Shaver et al. 2020a, 2020b)
- Marine threats to sea turtles such as contaminants, commercial shipping and fishing, marine debris, etc. (Wang et al. 2003, 2006; Faust et al. 2014; Hart et al. 2018; Purvin et al. 2020)
Stranding trends including stranding due to cold stunning and fibropapillomatosis (disease) (Caillouet et al. 1991, 1995, 1996, 2016b; Shaver 1990, 1994, 1995b, 1998a, 1998b, 1999, 2000; Lewison et al. 2003; Tristan et al. 2010; Shaver et al. 2017, 2019c; Frandsen et al. 2020; Stacy et al. 2020).
Anderson, J.D., D.J. Shaver, and W.J. Karel. 2013. Genetic diversity and natal origins of green turtles (Chelonia mydas) in the Western Gulf of Mexico. Journal of Herpetology 47(2):251–257.
Avens, L., L.R. Goshe, L. Coggins, D.J. Shaver, and B. Higgins. 2017. Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp’s ridley sea turtles (Lepidochelys kempii) in the Gulf of Mexico. PLOS ONE 12(3): e0173999. doi: 10.1371/journal.pone.0173999.
Bjorndal, K.A., A.B. Bolten, B. Koike, B.A. Schroeder, D.J. Shaver, W.G. Teas, and W.N. Witzell. 2001. Somatic growth function for immature loggerhead sea turtles in southeastern U.S. waters. Fishery Bulletin 99:240–246.Bjorndal, K.A., A.B. Bolten, M. Chaloupka, V.S. Saba, C. Bellini, M. A.G. Marcovaldi, A.J.B. Santos, L.F. Wurdig Bortolon, A.B. Meylan, P.A. Meylan, J. Gray, R. Hardy, B. Brost, M. Bresette M., J.C. Gorham, S. Connett, B. Van Sciver Crouchley, M. Dawson, D. Hayes, C.E. Diez, R.P. van Dam, S. Willis, M. Nava, K.M. Hart, M.S. Cherkiss, A.G. Crowder, C. Pollock, Z. Hillis-Starr, F.A. Muñoz Tenería, R. Herrera-Pavón, V. Labrada-Martagón, A. Lorences, A. Negrete-Philippe, M.M. Lamont, A.M. Foley, R. Bailey, R.R. Carthy, R. Scarpino, E. McMichael, J.A. Provancha, A. Brooks, A. Jardim, M. López-Mendilaharsu, D. González-Paredes, A. Estrades, A. Fallabrino, G. Martínez-Souza, G.M. Vélez-Rubio, R.H. Boulon, Jr., J.A. Collazo, R. Wershoven, V. Guzmán Hernández, T.B. Stringell, A. Sanghera, P.B. Richardson, A.C. Broderick, Q. Phillips, M. Calosso, J.A.B. Claydon, T.L. Metz, A.L. Gordon, A.M. Landry, Jr., D.J. Shaver, J. Blumenthal, L. Collyer, B.J. Godley, A. McGowan, M.J. Witt, C.L. Campbell, C.J. Lagueux, T.L. Bethel, and L. Kenyon. 2017. Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic. Global Change Biology 2017:1–13. doi: 10.1111/gcb.13712.
Bowen, B.W., A.L. Bass, S.M. Chow, M. Bostrom, K.A. Bjorndal, A.B. Bolten, T. Okuyama, B.M. Bolker, S. Epperly, E. LaCasella, D.J. Shaver, M. Dodd, S.R. Hopkins-Murphy, J.A. Musick, M. Swingle, K. Rankin-Baransky, W. Teas, W.N. Witzell, and P.H. Dutton. 2004. Natal homing in juvenile loggerhead turtles (Caretta caretta). Molecular Ecology 13(12):3797–3808. doi: 10.1111/j.1365-294x.2004.02356.x.
Bowen, B.W., W.S. Grant, Z. Hillis-Starr, D.J. Shaver, K.A. Bjorndal, A.B. Bolten, and A.L. Bass. 2007a. The advocate and the scientist: debating the commercial exploitation of endangered hawksbill turtles. Molecular Ecology 16:3514–3515.
Bowen, B.W., W.S. Grant, Z. Hillis-Starr, D.J. Shaver, K.A. Bjorndal, A.B. Bolten, and A.L. Bass. 2007b. Mixed-stock analysis reveals migration of juvenile hawksbill turtles (Eretmochelys imbricata) in the Caribbean Sea. Molecular Ecology 16:49–60.
Caillouet, C.W., Jr., M.J. Duronslet, A.M. Landry, Jr., and D.J. Shaver. 1991. Sea turtle strandings and shrimp fishing effort in the northwestern Gulf of Mexico, 1986–1989. Fishery Bulletin 89(4):712–718.
Caillouet, C.W., Jr., C.T. Fontaine, S.A. Manzella-Tirpak, and D.J. Shaver. 1995. Survival ofhead-started Kemp's ridley sea turtles (Lepidochelys kempii) released into the Gulf ofMexico or adjacent bays. Chelonian Conservation and Biology 1(4):285–292.
Caillouet, C.W., Jr., D.J. Shaver, W.G. Teas, J.N. Nance, D.B. Revera, and A.C. Cannon. 1996. Relationship between sea turtle strandings and shrimp fishing effort in the northwestern Gulf of Mexico: 1986–1989 versus 1990-1993. Fishery Bulletin 94(2):237–249.
Caillouet, C.W., Jr., D.J. Shaver, A.M. Landry, Jr., D.W. Owens, and P.C.H. Pritchard. 2011. Commentary: Kemp’s ridley sea turtle (Lepidochelys kempii) age at first nesting. Chelonian Conservation and Biology 10(2):288–293.
Caillouet, C.W., Jr., B.J. Gallaway, and N.F. Putman. 2016a. The Kemp’s ridley sea turtle saga and setback: novel analyses of cumulative hatchlings released and time-lagged annual nests in Tamaulipas, Mexico. Chelonian Conservation and Biology 15:115–131.
Caillouet, C.W., Jr., N.F. Putman, D.J. Shaver, R.A. Valverde, E.E. Seney, K.J. Lohmann, K.L. Mansfield, B.J. Gallaway, J.P. Flanagan, and M.H. Godfrey. 2016b. A call for evaluation of the contribution made by rescue, resuscitation, rehabilitation, and release translocations to Kemp’s ridley (Lepidochelys kempii) population recovery. Herpetological Conservation and Biology 11:486–496.
Craven, C. K., J.Y.S. Hodgson, D.J. Shaver, J.S. Walker, M.R. Villalba-Guerra, and D.W. Owens. 2019. Evaluation of gonadal tissue to validate size at reproductive maturity in Kemp’s ridley sea turtles found stranded in Texas, USA. Diversity 11(5):76. doi:10.3390/d11050076.
Culver, M., J.C. Gibeaut, D.J. Shaver, P. Tissot, and M. Starek. 2020. Using lidar data to assess the relationship between beach geomorphology and Kemp’s ridley (Lepidochelys kempii) nest site selection along Padre Island, TX, United States. Frontiers in Marine Science 7:214.
Faust, D.R., M.J. Hooper, G.P. Cobb, M. Barnes, D.J. Shaver, S. Ertolacci, and P.N. Smith. 2014. Inorganic elements in green sea turtles (Chelonia mydas): Relationships among external and internal tissues. Environmental Toxicology and Chemistry 33(9):2020–2027. doi: 10.1002/etc.2650.
Frandsen, H.R., C.M. Purvin, M.R. Villalba-Guerra, and D.J. Shaver. 2020. Chelonia mydas (green sea turtle). Reproductive abnormality. Herpetological Review 51(2):312.
Frey, A., P.H. Dutton, D.J. Shaver, J.S. Walker, and C. Rubio. 2014. Abundance of nesting Kemp’s ridley turtles (Lepidochelys kempii) in Texas: a novel approach using genetics to improve population census. Endangered Species Research 23:63–71.
Fuentes, M.M.P.B., M.H. Godfrey, D.J. Shaver, S.A. Ceriani, C. Gredzens, R. Boettcher, D. Ingram, M. Ware, and N. Wildermann. 2019. Exposure of marine turtle nesting beaches to named storms along the continental USA. Remote Sensing 11(24):2996.
Fuentes, M.M.P.B, S.A. Ceriani, M.H. Godfrey, C. Gredzens, D. Helmers, D. Ingram, M. Pate, V.C. Radeloff, D.J. Shaver, and N. Wildermann. 2020. Potential adaptability of marine turtles to climate change may be hindered by coastal development. Regional Environmental Change 20:104.
Gallaway, B.J., W.J. Gazey, C.W. Caillouet, Jr., P.T. Plotkin, F.A. Abreau Grobois, A.F. Amos, P.M. Burchfield, R.R. Carthy, M.A. Castro Martinez, J.G. Cole, A.T. Coleman, M. Cook, S. DiMarco, S.P. Epperly, M. Fujiwara, D. Gomez Gamez, G.L. Graham, W.L. Griffin, F. Illescas Martinez, M.M. Lamont, R.L. Lewison, K.J. Lohmann, J.M. Nance, J. Pitchford, N.F. Putman, S.W. Rayborn, J.K. Rester, J.J. Rudloe, L. Sarti Martinez, M. Schexnayder, J.R. Schmid, D.J. Shaver, C. Slay, A.D. Tucker, M. Tumlin, T. Wibbels, and B.M. Zapata Najera. 2016a. Development of a Kemp’s ridley sea turtle stock assessment model. Gulf of Mexico Science 33(2):138–157.
Gallaway, B.J., W.J. Gazey, T. Wibbels, E. Bevan, D.J. Shaver, and J. George. 2016b. Evaluation of the status of Kemp’s ridley sea turtle following the 2010 Deepwater Horizon Oil Spill. Gulf of Mexico Science 33(2):192–205.
Hart, K.M., A.R. Iverson, I. Fujisaki, M.M. Lamont, D. Bucklin, and D.J. Shaver. 2018. Marine threats overlap key foraging habitat for two imperiled sea turtle species in the Gulf of Mexico. Frontiers in Marine Science 5:336 doi: 10.3389/fmars.2018.00336.
Howell, L.N., K.J. Reich, D.J. Shaver, and A.M. Landry, Jr., C.C. Gorga. 2016. Ontogenetic shifts in diet and habitat of juvenile green sea turtles in the northwestern Gulf of Mexico. Marine Ecology Progress Series 559:217–229. doi: 10.3354/meps11897.
Hurtado, L., X.de la Rosa-Reyna, M. Mateos, D.J. Shaver, J. Thiltges, R. Metz, J. Hill, and C. Johnson. 2016. Thousands of SNPs in the critically endangered Kemp’s ridley sea turtle (Lepidochelys kempii) revealed by ddRAD-seq: opportunities for previously elusive conservation genomics research in this species. Gulf of Mexico Science 33(2):214–218.
Lewison, B., L. Crowder, and D.J. Shaver. 2003. The impact of Turtle Excluder Devices and fisheries closures on loggerhead and Kemp’s ridley strandings in the western Gulf of Mexico. Conservation Biology 17(4):1089–1097.
Morreale, S.J., P.T. Plotkin, D.J. Shaver, and H. Kalb. 2007. Migration and movements of ridley turtles. In: Biology and Conservation of Ridley Sea Turtles, p. 213–230. P.T. Plotkin (editor). The Johns Hopkins University Press.
Putman, N.F., K.L. Mansfield, R. He, D.J. Shaver, and P. Verley. 2013. Predicting the distribution of oceanic-stage Kemp’s ridley sea turtles. Biology Letters 9:20130345. doi.org/10.1098/rsbl.2013.0345.
Putman, N., E, Seney, P. Verley, D. Shaver, M. López-Castro, M. Cook, V. Guzmán, B. Brost, S. Ceriani, R. Díaz Mirón, J. Peña, M. Tzeek, R. Valverde, C. Cantón, L. Howell, J. Ley, M. Tumlin, W. Teas, C.W. Caillouet Jr., E. Cuevas, B. Gallaway, P. Richards, and K. Mansfield. 2020. Predicted distributions and abundances of the sea turtle “lost years” in the western North Atlantic Ocean. Ecography. 43:506–517 doi: 10.1111/ecog.04929
Purvin, C.M., M.R. Villalba-Guerra, H.R. Frandsen, and D.J. Shaver. 2020. Chelonia mydas (Green sea turtle) incidental capture. Herpetological Review. 51(2) 311–312.
Rafferty, P., D.J. Shaver, H.R. Frandsen, and M. Montello. 2019. Lepidochelys kempii (Kemp’s ridley sea turtle). Nesting. Herpetological Review 50(2):350.
Reich, K.J., M.C. López-Castro, D.J. Shaver, C. Iseton, K.M. Hart, C.J. Schmitt, and M.J. Hooper. 2017. Changes in the foraging strategy of Kemp’s ridley (Lepidochelys kempii) in the northern Gulf of Mexico post Deepwater Horizon Spill. Endangered Species Research 33:281–289.
Richards, P.M., S.P. Epperly, S.S. Heppell, R.T. King, C.R. Sasso, F. Moncada, G. Nordase, D.J. Shaver, Y. Medina, and J. Zurita. 2011. Sea turtle population estimates incorporating uncertainty: a new approach applied to western North Atlantic loggerheads (Caretta caretta). Endangered Species Research 15:151–158.
Schmid, J.R., H.R. Frandsen, P.H. Dutton, A. Frey, and D.J. Shaver. 2020. Lepidochelys kempii (Kemp’s ridley sea turtle). Life history. Herpetological Review 51(1):109–110.
Shamblin, B.M., P.H. Dutton, D.J. Shaver, D.A. Bagley, N.F. Putman, K.L. Mansfield, L.M. Ehrhart, L.J. Peña, and C.J. Nairn. 2016. Mexican origins for the Texas green turtle foraging aggregation: a cautionary tale of incomplete baselines and poor marker resolution. Journal of Experimental Marine Biology and Ecology doi: 10.1016/j.jembe.2016.11.009.
Shaver, D.J. 1989. Green sea turtle geographic distribution. Herpetological Review 20(1):14.
Shaver, D.J. 1990. Hypothermic stunning of sea turtles in Texas. Marine Turtle Newsletter 48:25–27.
Shaver, D.J. 1991. Feeding ecology of Kemp's ridley in south Texas waters. Journal of Herpetology 25(3):327–334.
Shaver, D.J. 1992. Kemp's ridley sea turtle reproduction. Herpetological Review 23(2):59.Shaver, D.J. 1994. Sea turtle strandings along the Texas coast reach alarming levels. Marine Turtle Newsletter 66:8–9.
Shaver, D.J. 1995a. Kemp's ridley sea turtles nest in south Texas. Marine Turtle Newsletter 70:10–11.Shaver, D.J. 1995b. Sea turtle strandings along the Texas coast again cause concern. Marine Turtle Newsletter 70:2–5.
Shaver, D.J. 1998a. Sea turtle strandings along the Texas coast, 1980-94. In: Characteristics of Texas Marine Strandings, p. 57–72. R. Zimmerman (editor). NOAA Technical Reports NMFS 143.
Shaver, D.J. 1998b. Sea turtle strandings in Texas. In: Report of the Sea Turtle Health Assessment Workshop, 2-3 February 1998, Part I: Background and Information Needs, Charleston, South Carolina, p. 75–80. P.A. Fair and L.J. Hansen (editors). NOAA Technical Memorandum NOS-NCCOS-CCEHBR-003.
Shaver, D.J. 1999. Sea turtle strandings in the Gulf of Mexico. In: Sharing our Gulf Conference Proceedings, June 10–12, 1998, College Station, Texas, p. 31–33. D. Owens (compiler) and M. Evans (editor). Texas Sea Grant Program, TAMU-SG-99-104.
Shaver, D.J. 2000. Distribution, residency, and seasonal movements of the green sea turtle, Chelonia mydas (Linnaeus, 1758), in Texas. Unpublished Ph.D. Dissertation, Texas A&M University. 273 pp.
Shaver, D.J., and A. Amos. 1988. Sea turtle nesting on Texas beaches in 1987. Marine Turtle Newsletter 42:7–9.Shaver, D.J., and J.E. Miller. 1999. Kemp’s ridley sea turtles return to Padre Island National Seashore. Park Science 19(2):16–17, 39.
Shaver, D.J. and H.R. Frandsen. 2019. Eretmochelys imbricata (Hawksbill Sea Turtle). Nesting. Herpetological Review 50(2):350–351.
Shaver, D.J., and M.M. Streich. 2019. Sea turtles. In: Texans on the Brink, Threatened and Endangered Animals, p. 161–167. B.R. Chapman and W.I. Lutterschmidt (editors). Texas A&M University Press. ISBN: 9781623497316l
Shaver, D.J., A.F. Amos, B. Higgins, and J. Mays. 2005. Record 42 Kemp’s ridley nests found in Texas in 2004. Marine Turtle Newsletter 108:1–3.
Shaver, D.J., C. Rubio, J.S. Walker, J. George, A.F. Amos, K. Reich, C. Jones, and T. Shearer. 2016. Kemp’s ridley sea turtle (Lepidochelys kempii) nesting on the Texas coast: geographic, temporal, and demographic trends through 2014. Gulf of Mexico Science 33(2):158–178.
Shaver, D.J., P.E. Tissot, M.M. Streich, J.S. Walker, C. Rubio, A.F. Amos, J.A. George, and M.R. Pasawicz. 2017. Hypothermic stunning of green sea turtles in a western Gulf of Mexico foraging habitat. PLoS ONE 12(3): e0173820. doi 10.1371/journal.pone.0173920.
Shaver, D.J., H.R. Frandsen, and J.S. Walker. 2019a. Dermochelys coriacea (Leatherback sea turtle). Nesting. Herpetological Review 50(2):350.
Shaver, D.J., H.R. Frandsen, J.S. Walker, M.A. Montello, S. Thurman, C.J. Nairn, B.M. Shamblin, P.H. Dutton, and A. Frey. 2019b. Chelonia mydas (Green sea turtle). Nesting Behavior. Herpetological Review 50(3):555–556.
Shaver, D.J., J.S. Walker, T.F. Backof. 2019c. Fibropapillomatosis prevalence and distribution in green turtles, Chelonia mydas, in Texas (USA) Diseases of Aquatic Organisms 136:175–182.
Shaver, D.J., H.R. Frandsen, C.M. Purvin, H.M. Wilson, L.E. Sundquist, M.A. Devlin, and B.A. Stacy. 2020. Chelonia mydas (green sea turtle). Predation. Herpetological Review 51(3):574–575.
Shaver, D.J., H.R. Frandsen, J.S. Walker, J.A. George, C. Gredzens. 2020b. Threats to Kemp’s ridley sea turtle (Lepidochelys kempii Garman, 1880) nests incubating in situ on the Texas coast. Herpetology Notes 13:907–923.
Stacy, B.A., R. Hardy, D.J. Shaver, C.M. Purvin, L. Lowell, H.M. Wilson, M.A. Devlin, A. Krauss, C. Macon, M. Cook, Z. Wang, L. Flewelling, J. Keene, A. Walker, P. Baker, and T. Yaw. 2020. 2019 sea turtle strandings in Texas: a summary of findings and analyses. NOAA Technical Memorandum NMFS-OPR-66, 64 p.
Tristan, T., D.J. Shaver, J. Kimbro, T. deMaar, T. Metz, J. George, and A. Amos. 2010. Identification of Fibropapillomatosis in green sea turtles (Chelonia mydas) on the Texas coast. Journal of Herpetological Medicine and Surgery 20(4):109–112.
Wang, H.-C., A. Landry, F. Kenyon, G. Gill, L. Kenyon, S. Presti, D. Shaver-Miller. 2003. Mercury concentration in Kemp’s ridley sea turtles from the Gulf of Mexico and South Atlantic. Abstract 260, In: The Society of Environmental Toxicology and Chemistry (SETAC) 24th Annual Meeting in North America, 9-13 Nov. 2003, Austin, Texas.
Wang, H.-C., A.M. Landry Jr., G.A. Gill, and D. Shaver. 2006. Trace metal levels in sea turtles stranded along the Texas coast. Proceedings of the Twenty-third annual Symposium on Sea Turtle biology and conservation. NOAA Technical Memorandum NMFS-SEFSC-536, 261 p.