Sea Turtle Populations In Free Fall Around the World

Dear EarthTalk: How are populations of sea turtles faring these days?

—A.J., Los Angeles, CA

Swimming alongside a sea turtle in coastal waters is certainly a thrilling sensation, but the experience is becoming increasingly harder to come by. Declines in sea turtle populations around the world and in U.S. waters over recent decades is a sad reminder of all the environmental offenses that contribute to making the world’s oceans less hospitable to these majestic, iconic reptiles.

Since the dawn of the Industrial Age, global sea turtle populations have decreased by 2/3, with only 6.5 million sea turtles left today. Credit: Pexels.com.

Researchers estimate that since the dawn of the Industrial Age in the early 20th century, global sea turtle populations have decreased by as much as two-thirds overall. These days only about 6.5 million sea turtles roam the world’s subtropical and tropical coastlines. Indeed, sea turtle populations are on the ropes: Three out of the world’s seven sea turtle species are considered “critically endangered” by the International Union for the Conservation of Nature (IUCN); green sea turtle numbers have fallen by some 90 percent while Leatherbacks have lost 40 percent of their population. Strict conservation measures are needed if we are to save these species outright.

But why even care about the turtles? They might seem like any other sea creature, but they are actually vital to maintaining a balanced environment. Turtle’s graze on seagrass meadows to regulate their growth and prevent them from suffocating. Unhatched eggs are also a vital source of nutrients to sand dunes, which allow vegetation to grow. So, if our turtle populations become too low, it will cause a chain reaction within the whole shoreline ecosystem.

Determining the exact lifespan of sea turtles is challenging due to their lengthy maturation process and the vast, uncharted waters they inhabit. However, scientists generally agree that the lifespan of most sea turtle species is comparable to that of humans.

  • Maturation Period: Sea turtles often take 20 to 30 years to reach maturity.
  • Reproductive Activity: After maturing, they remain reproductively active for about a decade.

On average, sea turtles live around 50 years. However, some individuals have been known to surpass this, with estimates suggesting they can live up to 70 or even 80 years.

Sea turtles have a unique anatomy that sets them apart from many of their terrestrial relatives. Their shells are part of their spine and have evolved from their ribs into an external structure. This specialized shell design offers protection but comes with certain limitations.

Unlike other turtles, sea turtles have paddle-shaped flippers and elongated necks that cannot retract into their shells. These adaptations are crucial for their aquatic lifestyle, allowing them to swim efficiently in the ocean. However, this same adaptation means they can’t withdraw their limbs and head for protection.

While the tough exterior of their shells does provide some defense against predators, the inability to retract makes sea turtles more susceptible to attacks. Predators such as tiger sharkskiller whales, and even terrestrial animals like raccoons pose a significant threat, especially to their eggs and hatchlings.

Unfortunately, populations of sea turtles face myriad threats. For starters, sea turtles often mistake plastic bags for jellyfish, one of their favorite delicacies. But this plastic can get stuck in the turtle’s stomach, imitating their sensation of being full which causes them to not eat any actual food. Researchers estimate some 52 percent of turtles have eaten some type of plastic.

With sea level rises, many beaches and even smaller barrier islands are disappearing. Turtles therefore become confused as to where to lay their eggs, potentially making it so that they don’t lay any. In addition, as reptiles, the gender of their hatchlings relies on temperature. Higher equals females, and lower equals males. With global warming, beaches are warming up, drastically altering the male/female balance. This could potentially affect the breeding success of turtles, and contribute to the decline as well.

Why Is There a Shortage of Male Sea Turtles in Florida?

Florida has seen a dramatic decrease in male sea turtle populations, and the primary culprit is rising temperatures. The gender of sea turtles is determined by the temperature at which the eggs are incubated. When eggs incubate at temperatures above 31°C (about 88°F), they are more likely to hatch as female.

Due to record-high temperatures in Florida, the beach sand where these eggs are laid has become significantly hotter. Consequently, most eggs incubate at these elevated temperatures, resulting in a disproportionate number of female hatchlings.

In recent years, the male-to-female ratio of sea turtles in Florida has skewed heavily toward females, with males becoming increasingly rare. This gender imbalance is a direct result of the hotter incubation conditions, exacerbated by the state’s ongoing issues with climate change and rising temperatures.

The federal Endangered Species Act already protects turtles by making it illegal to harm them in any way, and provides resources to combat endangerment. Environmentalists have also created new programs like the State of the World’s Sea Turtles and the IUCN Turtle Specialist group which examine risk factors, data and potential conservation efforts.

Additionally, many volunteers come together during nesting and hatching season to protect and guide turtles. And their efforts have not gone to waste; Leatherback turtle nests in and around U.S. waters are up from 27 in 1989 to 614 in 2014 thanks to protections enacted under the Endangered Species Act. In addition, 3,960 nests have been counted on the Georgia Coast, a record for the state.

The Covid-19 pandemic brought an unexpected positive outcome for endangered leatherback sea turtles in Florida. As restrictions limited human activities and reduced waste on beaches, these turtles saw a noticeable improvement in their habitat. Researchers reported that the decreased presence of humans led to less disturbance and pollution, providing a safer and cleaner environment for the turtles. This significant environmental shift underscores how decreased human interference can benefit marine life.

By continuing to fund conservation efforts and with the help of volunteers, sea turtles can continue to thrive in the wild.

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How Far Do Sea Turtles Migrate During Their Lifetimes?

Sea turtles are known for their epic migrations, traveling impressive distances during their lifetimes. These journeys often span thousands of miles, from the open oceans to nesting beaches and back.

Leatherback Turtles

Leatherback turtles, for example, are true marathon swimmers. They can traverse around 16,000 kilometers (10,000 miles) or more each year across the vast Pacific Ocean.

Loggerhead Turtles

Loggerheads also demonstrate remarkable endurance. Some have been recorded migrating from Japan to Baja California, a trek of about 13,000 kilometers (8,000 miles).

Green Turtles and Olive Ridleys

On the other hand, species like green turtles and olive ridleys tend to stay closer to their home regions. Their migrations are comparatively shorter, but they still cover significant distances to fulfill their life cycles.

Despite the variation in their travel patterns, it’s clear that sea turtles are built for long-distance migration, showcasing one of nature’s most incredible survival strategies.

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