This Month in Science: Sea Turtle Season

Baby sea turtles are currently hatching all along the North Carolina coast. Sea turtle nesting season runs from April to September, and peaks during the month of June. As of June 30, 2022, 951 nests have been cataloged this season by the North Carolina Wildlife Resources Commission. There are currently four species of sea turtles (loggerheads, leatherbacks, greens, and Kemp’s Ridleys) nesting on the coast of North Carolina, but the majority of the nests (939) are loggerhead turtles.  

Loggerhead turtles, scientific name Caretta caretta, get their name because of their very large heads.  They have reddish-brown heart-shaped shells that can grow up to 3.5 feet in length and typically weigh between 155 and 375 pounds. Loggerheads have very strong jaws that allow them to eat hard-shelled fish like horseshoe crabs and mussels.   

It takes about 30 years for a female to reach sexual maturity. Once mature, females will travel back to the beaches where they hatched to make their own nests and lay their eggs. In some cases, this means the turtle will travel hundreds to thousands of miles to return “home”. A mature female will nest multiple times in a season, but will only nest every two to four years. She will lay 100-126 eggs per nest.  Almost half of nesting attempts will result in a false crawl—when a sea turtle climbs onto the beach, but returns to the ocean without nesting. Although researchers are not certain as to why this occurs, it is thought that something (predators, human activity, excessive lighting) disturbs their nesting behavior, prompting them to return to the ocean and try again at another time. After nesting, the female returns to the ocean, leaving her offspring to fend for themselves. 

The temperature of the nest determines whether the hatchlings will be male (82°F) or female (89°F). Temperatures in between that range will produce a nest of mixed male and female hatchlings. Eggs take about 60 days to incubate in the nest before hatching. Hatchlings will break out of their eggs and remain in the nest for a few days to absorb their yolk. The yolk gives them the energy they will need to trek into the ocean and deeper waters.  

Once they reach the water, loggerheads will migrate thousands of miles to get to the safety of the open ocean, often within the Sargasso Sea located between the United States and the west coast of Africa within the Atlantic Ocean. This migration is extremely dangerous, and it is estimated that only one turtle in 1,000-4,000 will survive the journey. Because the hatchlings are not strong enough to dive, they must remain at the surface, making them extremely vulnerable to coastal predators.  

How exactly does a baby turtle navigate the open ocean without any guidance? Loggerhead turtles are born with an innate ability to detect magnetic fields and navigate via subtle changes in the fields around Earth. Using fluctuations in magnetic fields as “landmarks”, loggerheads traverse the ocean, making specific turns to conserve energy by taking advantage of currents. Once they reach sexual maturity, turtles will mate in coastal waters, and females will travel back to their original nest to start the cycle again.  

The average lifespan of a loggerhead is thought to be around 50 years in the wild, however there are many threats to their survival. All sea turtle populations are in decline mainly due to unregulated fishing, pollution, destruction of habitat, and climate change. Loggerhead turtles have been listed as threatened since 1978. There are many conservation efforts underway to encourage growth in their populations, but there are also some things that you can do personally:  

  • Use a red flashlight if you are out on the beach at night to avoid disturbing nesting turtles 
  • Stay away from known nesting sites 
  • Make sure plastic trash gets thrown away properly, so it doesn’t end up in the ocean 
  • Keep all dogs on a leash  
  • If you’re on the beach, make sure outdoor lights and any motion sensors are turned off at night during nesting season; and remove any beach furniture 
  • If you dig a hole at the beach, be sure to fill it in before you leave so turtles don’t get trapped 
  • If you built a sandcastle, make sure to knock it down and flatten the sand before you leave 

If you want to see a live sea turtle, you can visit the North Carolina Aquarium at Fort Fisher or the Karen Beasley Sea Turtle Rescue and Rehabilitation Center.   

Previous Columns

May 2022: Ghost Trees
March 2022: Jellyfish
January 2022: Venus Flytrap
November: Citizen Science
September: Hurricane Season
July: Plastic Free July
June: All About Alligators
May: Rain Gardens
April: Bald Cypress Trees and The Climate Record
March: Ocean Waves
February: The Scientific Method
January 2021: Static Electricity

 


Loggerhead hatchlings trek towards the ocean.
Image credit: Camp Lejeune Photos
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