A biologist documents a Kemp's ridley sea turtle nesting on the beach.
NPS Photo.
Kemp’s ridley (Lepidochelys kempii) sea turtle nests have been recorded on the Texas coast since 1948 (Shaver and Caillouet 1998, Shaver 2005). Restoration activities for Kemp’s ridleys began in Texas in 1978, as part of the multi-agency, bi-national Kemp’s Ridley Sea Turtle Restoration and Enhancement Program (Shaver 1987, Shaver 1996a, 1996b, NMFS et al. 2011). Part of this species recovery effort included an attempt to increase nesting of this native species at Padre Island National Seashore and form a secondary nesting colony here, as a safeguard against extinction (Shaver 1987, Caillouet et al. 2015, Shaver and Caillouet 2015). From 1978 to 1988, 22,507 Kemp's ridley eggs were shipped to PAIS from Rancho Nuevo, Mexico for experimental imprinting (Shaver 2007). Next, the 15,875 resulting hatchlings were shipped to the National Marine Fisheries Service (NMFS) Laboratory in Galveston, Texas for head-starting (Shaver 2005, 2007, Shaver and Wibbles 2007). Evaluating the effectiveness of the head-start experiment was contingent on recapturing and identifying turtles that were raised and released as part of this program. Therefore, before release most head-started turtles were tagged externally (living tag, metal tag), internally (coded wire tag, passive integrated transponder [PIT] tag), or both (Caillouet et al. 1995, Shaver 1996a, Shaver 2007, Fontaine and Shaver 2005, Shaver and Wibbles 2007, Shaver et al. 2016b).
Systematic efforts to locate, document, and protect nesting Kemp’s ridley turtles and their nests in Texas began at Padre Island National Seashore in 1986, but patrols were not comprehensive until 1998 (Shaver and Caillouet 1998, 2015, Shaver 2005). Whenever possible, nesting Kemp’s ridleys were examined for the presence of living, PIT, coded wire, or metal tags that could link them to head-starting or to a previous nesting event (Shaver and Caillouet, 2015). PIT and metal tags were applied to those nesters that lacked them. Carapace measurements were also taken on nesting turtles and a skin biopsy and sometimes a blood sample were taken for genetic studies (Dutton et al. 2006, Frey et al. 2014, Hurtado et al. 2016).
Researchers attempt to locate and confirm nests at all locations where nesting Kemp’s ridley turtles or their tracks are found in Texas (Shaver and Caillouet 2015). Eggs are moved from all nests located during egg laying to an incubation facility or corral to enhance recruitment (Shaver and Caillouet 2015, Shaver et al. 2016b, Backof et al. 2019). On rare occasions, nests are not found at egg laying and incubate unprotected (in situ). After hatching of all protected nests, researchers enumerate clutch size, hatching success (number of live and dead hatchlings/clutch size), emergence success (number of live hatchlings/clutch size), and number of hatchlings released (Shaver 1989, Shaver and Chaney 1989, Shaver and Caillouet 2015, Backof et al. 2019). However, these parameters often cannot be accurately quantified for in situ nests due to predation, other disturbances at the nest site, or lack of monitoring through hatchling release.
Kemp's ridley sea turtle hatchlings entering the Gulf of Mexico.
NPS Photo.
About one nest was documented in Texas every three years from 1948 through 1994, but patrol effort was minimal during those years. Documented nesting in Texas and Mexico increased from 1995 through 2009 and has fluctuated since then (Shaver and Caillouet 2015, Bevan et al. 2016, Caillouet et al. 2016, Gallaway et al. 2016a, 2016b, Shaver et al. 2016a, Caillouet et al. 2018). Most Kemp’s ridley nests recorded in the USA have been found in south Texas (Mustang Island southward), which is the documented historic nesting range for this species in the USA (Shaver 2005). About 52.4% of the Kemp’s ridley nests found in the USA have been recorded at Padre Island National Seashore, making it the most important Kemp’s ridley nesting beach in the country (Shaver et al. 2016b).
Scientists with the Division of Sea Turtle Science and Recovery continue to document the recovery of the Kemp’s ridley sea turtle. The sudden and unexpected decline and fluctuation in Kemp's ridley numbers since 2010 demonstrates the importance of continued long-term monitoring, protection, and conservation actions. Research conducted by the Division of Sea Turtle Science and Recovery highlights the importance of Padre Island National Seashore for the recovery of the critically endangered Kemp’s ridley sea turtle. This research is also vital to long-term efforts to increase understanding of our Texas State Sea Turtle who’s nesting distribution is limited almost exclusively to the western Gulf of Mexico.
Literature Cited:
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