Sea turtle eggs at Long Beach aquarium face imminent hatching

Twenty-four olive ridley sea turtle eggs are packed in styrofoam coolers at the Aquarium of the Pacific in Long Beach, waiting to hatch. This marks the first time sea turtle eggs have been incubated and released in California. The eggs are currently between layers of sand inside the coolers, where wireless sensors and cameras monitor the environment. Staff check on the setup three to four times a day, a frequency that will increase to every other hour as hatching day approaches.

The eggs are kept at a temperature of 85 to 86 degrees Fahrenheit. Dr. Lance Adams, the aquarium’s director of veterinary services, said if the eggs were developing, that process should be continuing. The species typically has an incubation period ranging from 45 to 60 days. On Saturday, it will be 45 days since the first clutch was laid. No one is certain if the eggs are fertilized or developing normally, but a successful hatch would be a first for the U.S. West Coast.

A female olive ridley crawled out of the surf near the Surfside community in Seal Beach on September 17 to deposit the first clutch. Three days later, on September 19, a second female laid eggs eight miles south in Huntington Beach. These nests were located in Orange County, far north of the species’ usual range. Olive ridleys typically nest in tropical regions of the Pacific, Indian, and Atlantic oceans, with major populations in Mexico, Nicaragua, Costa Rica, and Panama. Before September, the farthest known northern nest was in Baja California Sur, Mexico, approximately 700 miles south of Orange County.

Federal biologists decided to relocate the eggs to the aquarium on September 29. This last-minute move followed forecasts that high tides would swamp the nests. The National Weather Service extended flood advisories for all Southern California coastal counties through 2 p.m. on Friday. The advisories were originally scheduled to expire on Thursday at 1 p.m., said Devin Black, a meteorologist for the weather service’s Oxnard office.

The unexpected arrival of the turtles was driven by environmental factors. An extreme marine heat wave and a strong El Niño event have pushed Southern California water temperatures closer to those of the turtles’ typical nesting grounds. A spokesperson for the U.S. Fish and Wildlife Service noted that ocean temperatures above 68 degrees are ideal for olive ridley hatchlings. Although average late November water temperatures in Southern California are historically 5 to 7 degrees lower than that, the National Oceanic and Atmospheric Administration expects temperatures at hatch time to be suitable for newborn turtles.

Sand temperature also influences development. Warmer sand generally results in female hatchlings and shorter incubation periods, while cooler sand produces males and longer wait times. The aquarium has worked to maintain the ideal temperature zone, but Adams said it is unclear what role the first weeks spent on the sand in Orange County will play in the eggs' development.

Hatching will begin when cameras show the sand above the eggs starting to settle. The hatchlings will be kept in a dark location until evening. This timing ensures they conserve energy for release. In the wild, hatchlings remain clustered beneath the sand until nighttime, when predation risk drops. They then burst from the sand together and swim furiously to the open ocean, guided by moonlight and fueled by a temporary external yolk sac.

Adams described this phase as a frenzy swimming, where the turtles move continuously to reach pelagic areas. The aquarium wants to prevent them from expending this energy while waiting for darkness. Federal biologists will monitor surf conditions and currents at beaches near the aquarium. Once the turtles are ready, officials will choose the site best suited for survival. The hatchlings will be placed on the sand to crawl to the sea themselves.

The release will not be publicly announced in advance to reduce risks from light, sound, and crowds. Less than 1% of sea turtle hatchlings survive to adulthood. Females who survive often return to the general area where they hatched to lay their own eggs. Pamela Plotkin, a retired oceanography professor at Texas A&M University, wrote in an email that she expects 85-95% of the eggs to hatch. She believes a few may survive to adulthood and return to nest on a California beach in 10 to 15 years.