The Kemp’s ridley is the most endangered of all sea turtle species. Efforts to save the Kemp’s ridley began in the 1960s and continue today. Although much has been learned about the Kemp’s ridley, many more questions remain unanswered. In fact, many call the story of the Kemp’s ridley, the “Ridley Riddle.”
The Riddle Turtle
For a long time, the Kemp's ridley was a real mystery. Sailors, explorers, and fishermen had seen other species of sea turtles nesting on various beaches around the world. They had seen those turtles lay eggs and the nests hatch. Scientists had studied the nests of other species of sea turtles, but it seemed no one had seen a Kemp's ridley nest. Some thought it might not even be its own species but an infertile hybrid of two other species. But when fishermen caught a female Kemp's ridley sea turtles with eggs, the riddle deepened. If these turtles were a separate species, where did they nest?
Scientists searched for the nesting grounds of this sea turtle with no success. In 1951, the first published record of a Kemp's ridley nesting anywhere in the world was submitted by J.E. Werler. The turtle was seen nesting in 1948 on what would later be designated as Padre Island National Seashore. But there were thousands of Kemp's ridley turtles out in the Gulf of Mexico at that time. Where did the rest of the turtles nest? Finally, in the early 1960s, Dr. Henry Hildebrand from Corpus Christi, Texas, came upon some home video footage that would solve the mystery and launch an international campaign to save a species.
A Mystery Solved
Architect Andreas Herrera traveled between the U.S. and Mexico regularly in the 1940s. He had his own small plane and usually flew along the coast. He had heard rumors that hundreds of turtles sometimes crawled up onto one of the beaches he flew over. He was interested in seeing these turtles and started taking a video camera with him on his trips in case he ever saw them. One summer day in 1947, he looked down as he flew over an area in Mexico called Rancho Nuevo and saw a beach covered with turtles. Excited, he found a place to land his small plane, got his video camera, and captured the turtles on film.
That video footage wasn't discovered by the scientific community until the early 1960s, when Dr. Hildebrand saw it. Scientists were amazed - nothing like it had ever been seen. Thousands of sea turtles were on the beach, digging holes and laying eggs. There were so many turtles, some even dug up the eggs of others as they laid their own. The scientists estimated that 40,000 female Kemp's ridley sea turtles had come ashore to nest on that one day on the 16-mile stretch of beach at Rancho Nuevo (Hildebrand 1963).
Finally, the mystery was solved and the nesting grounds of the Kemp's ridley became known to the scientific world. But with the good news came the bad: this species was in serious trouble.
The 1947 film footage taken by Andreas Herrera showed the incredible mass nesting of tens of thousands of Kemp's ridley sea turtles on the beach at Rancho Nuevo in Tamaulipas, Mexico. Unfortunately, it also showed mass destruction. Scientists reviewing the footage in the 1960s saw people taking the turtles' eggs as they were laid and loading them by the millions into trucks. Some of the nesting females were also taken. The scientists estimated that 90% of the turtle nests were destroyed the same day they were laid.
If 90% of the nests laid were being destroyed, how long could the species survive? How long had this wholesale destruction been going on? Conservationists and scientists traveled to Rancho Nuevo and found the turtles were still nesting each year but had already declined dramatically since the film was taken years earlier. They appealed to the Mexican government to stop the wholesale destruction that was still taking place.
In 1966, the Mexican government took action. They passed legislation protecting the beach at Rancho Nuevo and brought in guards to stop the taking of eggs and turtles. Despite these protection efforts, the number of Kemp's ridley nests found each year continued to drop. By 1985, only 702 nests were found worldwide the entire year. Was it too late?
A Bold International Experiment
Rancho Nuevo is the heart, but not the entirety, of the Kemp's ridley nesting range. By the time scientists discovered it, the species was already plummeting toward extinction. As conservationists and scientists scrambled to learn more about the Kemp's ridley and how to save it, they found records indicating this sea turtle had historically nested on other beaches, as far south as Veracruz in Mexico and as far north as Mustang Island in Texas.
In the 1970s, the U.S. joined efforts to save this species. At the time, almost all known nesting of Kemp's ridley sea turtles was occurring at Rancho Nuevo. Nearly all Kemp's ridley eggs were literally in one basket! What if a hurricane, oil spill, or other disaster wiped out that beach? The species was very vulnerable. The situation was dire.
In 1974, the National Park Service proposed re-establishing a nesting colony at Padre Island National Seashore (PAIS). The seashore is part of the native nesting range of the Kemp's ridley and offers long-term protection for the turtle, its nests, and its nesting habitat. Boosting nesting at PAIS would help to re-establish a nesting colony at the northern end of the Kemp's ridley historic nesting range at a protected area in the U.S. where nesting had previously occurred. It would also provide safeguards against species extinction.
In 1978, agency officials from Mexico and the U.S. and conservationists agreed to attempt to re-establish a secondary nesting colony at Padre Island National Seashore to help save the species. They formed an international, multi-agency partnership and established the Kemp's Ridley Sea Turtle Restoration and Enhancement Program (KRREP). The National Park Service led development of an action plan for the KRREP. The goals of the plan were to re-establish a Kemp's ridley nesting colony at Padre Island National Seashore and to protect nesting turtles, eggs, and hatchlings at Rancho Nuevo (Caillouet et al. 2015, Shaver and Caillouet 2015).
The project was based on the theory that sea turtles imprint to their natal beach and that, as a result of this imprinting, adult females return to the beach where they hatched to lay their eggs. This theory was unproven at the time, and no project of this magnitude had been attempted before. But the Kemp's ridley was on the verge of extinction, and bold actions were needed to save the species.
The project began right away. From 1978-1988, eggs from a portion of the Kemp's ridley nests laid each year at Rancho Nuevo were collected, packed in sand from Padre Island, and transported to Padre Island National Seashore. Overall, a total of 22,507 eggs were collected and relocated through this project. Once the nests arrived at Padre Island National Seashore, they were incubated under controlled conditions and hatched. The newly hatched turtles were released on the beach at PAIS, allowed to crawl on the beach and into the surf, and then recaptured using aquarium dip nets after a brief swim in the Gulf of Mexico. This procedure was done in the hope that the hatchlings would imprint to the National Seashore and the females would return as adults to nest on Padre Island. This was the imprinting portion of the project.
Once the hatchlings were recaptured, they were transported to the National Marine Fisheries Service Laboratory in Galveston, Texas for the headstarting portion of the project. The turtles were kept and reared in Galveston for 9-11 months. The purpose of this headstarting was to allow the turtles to grow large enough to avoid most predators and to be tagged for future recognition to help evaluate project success.
After 9-11 months, the turtles were about 8 inches long. Each turtle was tagged with a numbered metal tag on its front flipper. Starting in 1982, each turtle was also marked with a "living tag" - a small plug of the lighter bottom shell (plastron) implanted into the darker upper shell (carapace). Finally, at one year of age, the turtles were released into the wild. Most were released into Gulf of Mexico waters off Mustang and North Padre Islands.
The Waiting Begins
How long does it take for a Kemp's ridley sea turtle to reach the age where it comes back to nest? At the time of this ambitious Imprinting and Headstarting Project, no one knew. In 1986, eight years after the first turtles from the project were released, Padre Island National Seashore staff began systematically searching the beaches from April to August for signs of nesting. But sporadic nesting of Kemp's ridleys had occurred on Padre Island since before the project began so they could only verify that a nest was laid by a female from the project if they saw the nesting turtle and identified either the metal tag or living tag. For years, a few nests were found but no females from the project were seen. Did this experiment work? Were they able to successfully imprint eggs from Mexico to Padre Island?
Finally, in 1996, beach patrollers found a Kemp's ridley with a living tag nesting on Padre Island! It was the first of dozens of females from the Imprinting and Headstarting Project that have been documented nesting on North Padre Island.
The Uphill Climb
Conservation efforts to save and recover the Kemp's ridley have continued and expanded over the years since the Imprinting and Headstarting Project ended in 1988. In Texas, organized patrols to find and protect Kemp's ridley and other sea turtle nests are now conducted not only at Padre Island National Seashore but, also in many other areas along the Texas coast. Through these programs, conducted by the National Seashore and many partners, Texas beaches are monitored each summer and any nesting sea turtles or nests found are protected. In Mexico, nest detection and protection programs that began at Rancho Nuevo have also increased and expanded to include most of the species nesting range in Mexico.
Protection of sea turtle nests is a key strategy in the fight to save the Kemp's ridley. Nests left where they are laid are at risk of predation, crushing by vehicles, tidal inundation, and other dangers. To increase hatching and survival of hatchlings, sea turtle nests found at Padre Island National Seashore and on most Texas beaches are moved to protected areas and monitored until they hatch. Most nests are also moved to protected areas or otherwise protected in Mexico. After hatching, the hatchlings are released into the wild, usually within 24 hours. At Padre Island National Seashore, the public is invited to watch some of these hatchling releases as long as it is compatible with the needs of the turtles.
In addition to protecting nests and boosting reproduction, other conservation measures have been taken to help the Kemp's ridley recover to healthy numbers. Research is being conducted to find out what areas in the marine environment are important for their survival. Nesting habitat is being protected and actions are being taken to reduce stranding of Kemp's ridley and other sea turtles. Stranding occurs when a turtle is no longer able to swim and floats helplessly in the water or washes up onto shore, alive or dead. Strandings can be caused by injury, disease, severe cold weather, entanglement in floating trash, incidental capture in fishing nets, and other hazards.
To help reduce stranding caused by incidental capture by fishing nets in the Gulf of Mexico, Turtle Excluder Devices (TEDs) are now required on all shrimping boats along the Texas coast and in many other areas. Additionally, beginning in 2000, Texas Parks and Wildlife Department closed nearshore waters off south Texas to shrimp trawling from December 1 through May 15. This area provides a nursery area for shrimp and a protective zone for migrating and nesting adult Kemp's ridley turtles. In Mexico, Gulf waters off Rancho Nuevo are also protected, with no shrimping or other commercial fishing allowed. Since these combined measures have been implemented, the number of Kemp's ridley sea turtles found stranded has decreased significantly.
The Results Are In - Or Are They?
Many years of combined conservation measures taken by Padre Island National Seashore and many local, state, national, and international partners resulted in a substantial increase in the number of Kemp's ridley nests found in Texas and in Mexico from 1997 through 2009. In 1996, only 6 Kemp's ridley nests were found in Texas; in 2012, 209 nests were found in Texas (Shaver and Caillouet 2015). After reaching a low of only 702 nests worldwide in 1985, Kemp's ridley nesting increased to a peak of nearly 20,000 nests worldwide in 2009! The intensive, bi-national conservations measures were working, and the species was on its way to recovery.
Unfortunately, this upward swing has taken a sudden and unexpected reversal in recent years. After 13 years of consistent increase, Kemp's ridley nesting decreased in 2010 and has fluctuated at reduced levels since then. Scientists are still working to determine the cause of this trend.
The sudden and unexpected decline in Kemp's ridley numbers demonstrates the importance of continued monitoring, protection, and conservation measures. History has shown that even when this species seemed lost, intensive efforts and cooperation between agencies, organizations, states, and nations turned the tide in favor of the Kemp's ridley. Conservation works, but requires combined efforts from many different partners and from many different directions. With the help of many partners, volunteers, and people like you, we can identify and address this most recent challenge to the recovery of the Kemp's ridley. Together, we can ensure our children and grandchildren can watch newly hatched Kemp's ridley turtles make their way across the beaches of Texas and Mexico.
Hildebrand, H.H. 1963. Hallazgo del area de anidacion de la tortuga marina "lora", Lepidochelys kempii (Garman), en la costa occidental del Golfo de Mexico (Rept., Chel.). Sobretiro de Ciencia, Mexico 22:105-112.
Shaver, D.J., and C.W. Caillouet, Jr. 2015. Reintroduction of Kemp's ridley (Lepidochelys kempii) sea turtle to Padre Island National Seashore, Texas and its connection to headstarting. Herpetological Conservation and Biology 10 (Symposium):378-435.
Werler, J.E. 1951. Miscellaneous notes on the eggs and young of Texas and Mexican reptiles. Zoologica 36:37-48.