Sea turtle populations are in decline around the world. Many species are listed as either endangered or threatened by the U.S. Fish & Wildlife Service. Increased human use and development have added to the natural threats, such as storms and predators, these fascinating reptiles encounter.
Learn more about the three types of endangered sea turtles that nest here on Alabama's Gulf Coast.
Green (Chelonia mydas)
Photo and text courtesy of Texas Fish & Wildlife Service
Green Sea Turtles range throughout the Atlantic, Pacific, and Indian Oceans primarily in the tropical regions. During the day, Green Sea Turtles feed in the sea grass beds that grow in shallow waters. At night, they sleep on the shallow bottom and sometimes out of the water on rocky ledges. Although sea turtles are subject to predation throughout their life cycle, predation is particularly high during the first two years of life. The eggs are eaten by raccoons, skunks, opossums, mongooses, coatis, and dogs. Hatchlings are preyed upon by mammals, sea birds, crabs, and carnivorous fishes. Predation continues to be high until the turtles are big enough to avoid being swallowed. Sharks are a formidable predator throughout the life cycle of the Green Sea Turtle.
Date of Listing: Threatened, 1970
Reason for Concern: The meat and eggs of the Green Sea Turtle have long been a source of food for people. Although international trade of wild Green Sea Turtles is against the law, capturing turtles for local consumption still persists in many central Pacific Islands, Southeast Asia and Indonesia, Indian Ocean islands, east coasts of Africa and Arabian peninsula, in Central and South America, and in Mexico. Exploitation of the nesting grounds either by human interference or pollution poses the greatest threat to these turtles. In the past, Green Sea Turtles were often killed in large shrimp trawl nets. Today, Turtle Excluder Devices (TED's) pulled by shrimp boats help reduce mortality from net entanglement.
Size: Shell length up to 55 inches and weights to 850 pounds.
Diet: Mostly sea grasses and algae, with small amounts of animal foods such as sponges, crustaceans, sea urchins, and mollusks.
Habitat (where it lives): Green Sea Turtles feed in shallow water areas with abundant sea grasses or algae. The turtles migrate from nesting areas to feeding grounds, which are sometimes several thousand miles away. Most turtles migrate along the coasts, but some populations are known to migrate across the ocean from nesting area to feeding grounds. The major nesting beaches are always found in places where the seawater temperature is greater than 25 C. As a species that migrates long distances, these turtles face special problems associated with differing attitudes toward conservation in different countries.
Life Span: At least 30 years and up to 50 years or more.
Reproduction: Adults reach sexual maturity between 8 and 13 years of age. Adults mate every 2 to 3 years during the nesting season just off the nesting beaches. Nesting occurs in numerous places in the tropics, including the beaches of the Gulf of Mexico, the Caribbean and Florida, Bermuda and the Cayman Islands. The turtles nest from March to October, with greatest activity along Gulf of Mexico beaches between June and August. The females may nest several times during a season, laying as many as 145 soft, round white eggs per nest.
Population Numbers: Unknown
Interesting Fact: The eggs incubate in the sand for 48 to 70 days. The incubation period is longer when the weather is cool. Hatchlings emerge from the nest mostly at night, race quickly to the surf and swim hurriedly toward the open ocean. The color of the hatchlings, black above and white below, is probably an adaptation to life near the surface in the open ocean, making them less conspicuous to fish and bird predators.
Kemps Ridley (Lepidochelys kempii)
Photo and text courtesy of Texas Fish & Wildlife Service. Photo by Bill Reaves.
Female turtles lay the majority of their eggs on a beach along the east coast of Mexico. It is the only known major nesting beach in the world for this turtle. Females nest in large groups called "arribazones". Groups of females move onto the beach to lay their eggs over a period of a few days. Each turtle digs a hole in the sand, deposits her eggs, and returns to the sea. In 50-55 days, the eggs hatch and the baby turtles (hatchlings) rush to the water and out to sea. After at least 10 years at sea, adult females return to nest at the same beach where they hatched. Male turtles never leave the water. They appear in waters near the nesting beach during the breeding season to mate with the females. Other than that, we know little about the males
Date of Listing: Endangered, 1970
Reason for Concern: Kemp's Ridley Sea Turtles are endangered because people dug up their eggs for food. Adult turtles were killed for food, and many have died from being tangled in large shrimp nets. Some turtles also die from eating trash, which they mistake for food.
Size: 28 inches in length and 75-100 lbs.
Diet: Mostly crabs; also shrimp, snails, clams, jellyfish, sea stars, fish
Habitat (where it lives): Gulf of Mexico and Atlantic Ocean.
Life Span: Individuals surviving to adulthood may live 30 years and possibly up to 50 years
Reproduction: 100 soft, white eggs average
Population Numbers: Most reliable counts are of nesting adult females, with estimates less than 1000 adult females
Interesting Fact: Scientists think baby sea turtles may remember or "imprint" on the particular smell, chemical make-up, or magnetic location of the beach where they hatched.
Loggerhead (Caretta caretta)
Photo and text courtesy of Texas Fish & Wildlife Service. Photo by Mike Lubich /USFWS.
Loggerhead Sea Turtles have characteristically large heads with powerful jaws. They are found worldwide in tropical and temperate waters with temperatures above 10 C. Although sea turtles are subject to predation throughout their life cycle, predation is particularly high during the first two years of life. Highest predation occurs during incubation and during the race of the hatchlings to the sea. The eggs are eaten by ghost crabs, raccoons, skunks, foxes, and dogs. Hatchlings are preyed upon by mammals, sea birds, crabs, and carnivorous fishes. Predation continues to be high until the turtles are big enough to avoid being swallowed by large carnivorous fishes such as groupers, snappers, and jacks. Sharks are a formidable predator throughout the life cycle of sea turtles, although larger turtles can often avoid a shark attack by presenting the flat side of the plastron or carapace to prevent biting.
Date of Listing: Threatened, 1978
Reason for Concern: Until the 1970's, Loggerhead turtles were commercially harvested for their meat, eggs, leather, and fat. Its meat and leather are not as valuable as the Green Sea Turtle, and its shell is of less value than the Hawksbill. However, in places where regulations are not enforced, the harvest of turtle meat and eggs remains a problem. Because of their feeding behavior and their habit of wintering in shallow waters, Loggerheads, along with Kemp's Ridley Sea Turtles, are more likely to be caught in large shrimp trawl nets and drown. Today, Turtle Excluder Devices (TED's) pulled by shrimp boats help reduce mortality from net entanglement by allowing many turtles to escape from the nets.
Size: Adults weigh 170 to 500 lbs. and have a carapace up to 45 inches in length.
Diet: Although feeding behavior may change with age, this species is carnivorous throughout its life. Hatchlings eat small animals living in seagrass mats which are often distributed along drift lines and eddies. Juveniles and adults show a wide variety of prey, mostly such as conchs, clams, crabs, horseshoe crabs, shrimps, sea urchins, sponges, fishes, squids, and octopuses. During migration through the open sea, Loggerheads eat jellyfishes, pteropods, floating molluscs, floating egg clusters, squids, and flying fishes.
Habitat (where it lives): Loggerheads are capable of living in a variety of environments, such as in brackish waters of coastal lagoons and river mouths. During the winter, they may remain dormant, buried in the mud at the bottom of sounds, bays, and estuaries. The major nesting beaches are located in the southeastern United States, primarily along the Atlantic coast of Florida, North Carolina, South Carolina, and Georgia. Only minor and solitary nesting has been recorded along the coasts of the Gulf of Mexico.
Life Span: At least 30 years and up to 50 years or more.
Reproduction: This is the only sea turtle that can nest successfully outside of the tropics, but the summer surface water temperature must be over 20 C.As with other sea turtles, females return to lay their eggs on or near the same beach where they hatched. Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach, but rather along the migration routes between feeding and breeding grounds. Females may nest several times during a breeding season (April- September), laying as many as 190 soft, round white eggs per nest. The eggs incubate in the sand for 55 to 75 days. The incubation period is longer when the weather is cool, and there is evidence that cooler incubation temperatures produce more male hatchlings. Hatchlings emerge from the nest mostly at night. After the majority of the hatchlings appear at the surface of the nest, they start a frenzied race toward the surf and out to sea.
Population Numbers: Unknown
Interesting Fact: Loggerhead hatchlings and juveniles are frequently associated with sea fronts (areas where ocean currents converge), downwellings, and eddies, where floating open ocean animals gather. The time that young turtles remain in these places feeding and growing is called the "lost year". During this period, young turtles float on rafts of seaweed with the currents, feeding on organisms associated with sargassum mats.