The Gulf of Mexico Oil Spill and a Lesson in Sea Turtle Population Ecology

Two months after the explosion, the Gulf of Mexico oil spill continues to threaten marine wildlife. We take a closer look at how sea turtle populations might be affected.

As we begin to count the duration of the Gulf of Mexico oil spill in months rather than weeks, news continues to break regarding the strife of the Kemp’s Ridley – the world’s smallest and most endangered of the sea turtle species. Hundreds of dead Kemp’s Ridley sea turtles have washed up on the shores of Louisiana, Mississippi, Florida and Alabama, over the past two months. Knowing that sea turtles frequently lay over one hundred eggs in a given clutch, one might be tempted to assume that these casualties have a minimal effect on the overall population – this assumption couldn’t be further from the truth!

Any former EPI student who has had the opportunity to study sea turtle ecology on the Caribbean Coast of Costa Rica knows the significance of these fatalities. In Costa Rica, our students partner with researchers from the Pacuare Reserve to monitor a critical leatherback sea turtle nesting beach. Using data like those collected by our students, scientists are able to gain insight into the size of the leatherback population, the average reproductive capacity and the importance of reducing sea turtle adult mortality.

For example, most research suggests that leatherbacks become reproductively mature at around 10 years old and can remain so for well over 20 years. Now, let’s imagine that they nest, on average, every three years during that time, and lay seven clutches per nesting season with 65 eggs per clutch. While these numbers can vary substantially, a little bit of simple arithmetic tells us that an average female leatherback sea turtle may lay over 3000 eggs in her lifetime ([20/3]x7×65=3033.33)! Of these 3000 eggs, only around 2 of her offspring, on average, will make it to adulthood to complete the cycle in a stable, gender-balanced, population.

The adult sea turtles that we encounter while patrolling the beaches in Pacuare or snorkeling the shores of the Galapagos are the lottery winners! Sadly, the same is true for the Kemp’s Ridley sea turtles that are washing up along the shores of the Gulf of Mexico. These are the few turtles that, against the odds, have survived the tumultuous life of a hatchling at sea. When we discuss adult sea turtle fatalities from issues like oil spills, bycatch, or harvesting it’s important to keep in mind how many eggs it will take to fill the voids those turtles have left behind and how important our conservation work is.

How you can help:

1. Learn More about the Kemp’s Ridley sea turtle, the impacts of oil on sea turtles and the rescue plans from the NOAA: National Oceanic and Atmospheric Administration

2. Support the Cause: Sponsor a sea turtle with EPI to protect adult Leatherbacks and their nests

3. Join Us: Help collect data on nesting leatherbacks on our Sea Turtle Ecology program in Costa Rica

4. Spread the Word: Send this page to a friend using the form in the upper right corner!

5. Contact Us: to learn about more ways to help