Olive ridleys exhibit two different nesting behaviors, the most prevalent of which is solitary nesting. Solitary nesting is relatively self-explanatory: females return to the beach where they were born to lay their eggs in a solitary nest. The less prevalent, but most notable, nesting behavior they exhibit is the synchronized mass nesting called an arribada. This is unique among sea turtle behavior and what olive ridleys are commonly known for. During these periods, hundreds of thousands of females will gather offshore of the nesting beach and simultaneously come ashore to lay their eggs. Females will nest one-to-three times per season annually once they reach maturity at 14 years of age. They will dig their nests to about 1.5 meters in depth and will lay approximately 100 eggs in each clutch. The nest is then covered by packing down the sand with their plastron (the underside of their bellies). 

During an arribada, the sheer number of females can cause limited spacing for nest sites, causing many of the previously laid nests to be accidentally dug up by new nesting females. Baby turtles will incubate for about 45-65 days before hatching. Hatchlings will emerge at night and move towards the brightest horizon, usually (and hopefully) the moon reflecting off the ocean. As in all sea turtle species, the sex of the hatchlings is determined by the temperature of the nest during the second trimester of incubation. Higher nest temperatures will yield more females, while lower nest temperatures will yield more males.  

Although there have been some studies on olive ridleys, the current population size is not well known. The National Oceanic and Atmospheric Administration (NOAA) five-year review of 2018 recorded that population trends varied depending on location. It was found that the endangered nesting populations of Mexico showed two increasing populations (Ixtapilla and La Escobilla), one decreasing population (Chacahua), and three stable populations (Mismaloya, Tlacoyunque, and Moro Ayuta). The review made a yearly estimate of about 1.39 million at-sea individuals, which it states is consistent with the increases seen on the eastern Pacific nesting beaches associated with those populations. NOAA also stated that the threatened populations in El Salvador, Guatemala, Costa Rica, and Panama show a declining trend, while populations in French Guiana and Brazil are small but increasing.  

Hatchlings and adults alike face many challenges during their lifetime. The olive ridley population is listed as threatened under the International Union for Conservation of Nature and Natural Resources (IUCN) Red List, with many outside influences contributing to their current status. A primary threat to olive ridleys is the unintended bycatch of adults. Fishing vessels use several different types of equipment to catch fish, and sea turtles can become entangled in their nets or lines, leading to drowning or serious injuries. Another primary threat is the direct harvest of turtles and eggs for food by humans and feral animals like dogs, cats, and pigs. Loss of living and nesting habitat, vessel strikes, ocean pollution, and changing ocean conditions are also contributing factors to the population’s decline in recent years. While there are many factors contributing to their decline, conservation efforts have aided in reducing the loss of these turtles. 

Several organizations have come together to aid in the protection of the olive ridley turtle. Commercial exploitation and trade in turtle shells, skins, and eggs has been largely reduced thanks to the protection status of the turtles by the IUCN. Other organizations, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Convention on Migratory Species (CMS), and the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC) have also provided protection for the turtles. 

Management during arribada events has helped to play a critical role in the conservation of sea turtle nesting grounds, greatly reducing the number of poached nest sites and harvested adult female turtles. Public outreach programs have also been instrumental in the education of local and global communities regarding the important role these animals play in the ecosystem, leading to the support of millions of people worldwide. The global movement to conserve all sea turtle species has led to the introduction of marine protected areas, controlled hatchling releases, beach clean-ups, and the use of turtle excluder devices in the fishing industry.  

Every bit of protection helps when it comes to saving a species, and we all can play a part. The better understanding we have of these turtles, the better equipped we will be to protect them now and in the future.

The Olive Ridley Sea Turtle

Photographs by Andre Seale