How the most endangered sea turtle likes to travel

Kemp’s ridleys are the most endangered sea turtle species in the world.

512px-Kemp's_Ridley_sea_turtle_nesting

Before conservation efforts, Kemp’s ridleys nested mainly on one 16-mile stretch of beach near Rancho Nuevo, Mexico. A film taken there in the 1940s showed around 40,000 individuals of the species partaking in group nesting, called an “arribada.” Unfortunately, this important nesting beach became a target for massive over-harvesting of eggs and their numbers plummeted shortly after the 1940s film. While it may have seemed to the harvesters that the population was impossible to harm due to its considerable size, the ocean is a dangerous place for hatchlings and chances of survival are slim. It can take hundreds of eggs to produce only one nesting adult, so every egg counts.

The Mexican government attempted to battle the declines by protecting the nesting beach starting in the mid-1960s but the number of nesters continued to drop. Ground-breaking conservation efforts in the late 1970’s between Mexico and the U.S. were taken to try to prevent total extinction of the species – scientists transported eggs from Rancho Nuevo to a protected beach in Texas. At that point the population was reaching critically low levels and on the brink of extinction. Less than 800 nests a year were estimated in the 1980s, accounting for only about 300 nesting females.

Further conservation laws established in the 1990s required an escape route for turtles caught in trawling nets (named Turtle Exclusion Devices; TEDs) in both U.S. and Mexican waters. These devices prevented accidental deaths during fishery operations, although compliance has not been consistent in either country. All of these conservation efforts eventually paid off, and in recent years numbers of nesters began to recover in Mexico (around 13,000 nests counted in 2010) and increase in Texas (around 150 nests in 2010), resulting in over one million hatchlings in 2010.

However, there are other threats in the Gulf of Mexico and its nesting beaches, from too much beach lighting at night to the Deepwater Horizon oil spill in 2010. Whatever the cause, Kemp’s ridley nest numbers decreased during 2013 and 2014 to a 7–8 year low.

In addition to being the rarest, Kemp’s ridleys are also the smallest sea turtle. While the shell of the largest sea turtle species, the leatherback, can measure up to 8 feet in length (they can weight up to 2,000 pounds!), Kemp’s ridleys only reach a little over 2 feet long (and weigh more like 100 pounds).

In a previous paper we looked at the foraging areas that Kemp’s ridleys use in the Gulf of Mexico. Next, we were interested in the areas they migrate through. Migration corridors are important because turtles need to swim through these waters to get to food (foraging area) or nesting grounds. With so many threats in the Gulf of Mexico, we wanted to define these migration areas to help with conservation efforts for these small sea turtles.

Our paper was published in Biological Conservation and you can read it here.

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