Sea Turtle Populations Are Making a Comeback

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sea turtle

By Dr. Becker

Story at-a-glance

  • Data from 299 sea turtle populations suggest most showed an upward, rather than downward, trend, over a period of six to 47 years, signaling a success in global sea turtle conservation efforts
  • Overall, 95 of the sea turtle populations increased while 35 decreased, and the rest were unchanged or had inadequate data to make the call
  • Of the seven species of sea turtles, six remain vulnerable, endangered or critically endangered

In 2014, researchers announced that they believe we are in the early stages of the planet’s sixth mass extinction event, caused by human activity. Over-exploitation such as poaching and fishing, habitat loss and environmental pollution are just some of the factors that have led amazing species like sea turtles to dwindle in numbers. Of the seven species of sea turtles, six are vulnerable, endangered or critically endangered.1 However, there’s good news to report.

Researchers from Aristotle University of Thessaloniki in Greece analyzed data on 299 sea turtle populations for time periods ranging from six to 47 years. Most populations showed an upward, rather than downward, trend, signaling a success in global sea turtle conservation efforts. Overall, 95 of the sea turtle populations increased while 35 decreased (and the rest were unchanged or had inadequate data to make the call).

“Positive trends in abundance are likely linked to the effective protection of eggs and nesting females, as well as reduced bycatch,” the researchers wrote,2 but noted that continued conservation and monitoring efforts will be crucial in the future.

Decades of Conservation Efforts Are Paying Off for Some Sea Turtles

Since the 1950s, efforts have been underway to save sea turtles. In the U.S., some areas have eliminated artificial lighting on beaches, which deters female turtles from nesting and may also disorient hatchlings. The use of turtle extruder devices (TEDs) by commercial fisheries has also helped. Trawling nets used by shrimp boats and others are notorious for catching sea turtles and other bycatch. Sea turtles have lungs and need to breathe oxygen at the water’s surface to survive, so if trapped by a net they can easily drown.

A TED is a special opening or escape hatch added to fishing nets that allow sea turtles to escape. While TEDs are effective, they’re not perfect. Sometimes trash can block the opening, preventing sea turtles’ escape. Further, they’re not required in every U.S. state, and even when they are required, they’re not always used.3 Other factors have also supported sea turtle conservation, most focusing on reducing illegal harvesting or relocating nests and hatcheries to protected areas. The researchers noted:4

“[P]ositive impacts of improved egg survival have been modeled at several nesting sites, such as the U.S. Virgin Islands and Tortuguero, Costa Rica. The reduced harvesting of turtles at sea [for example, green turtles in Hawaii] and reduced bycatch of turtles in fishing gear might have also helped population recoveries, for example, the use of TEDs, along with the modification of hook types in long-line fisheries.”

One success story centers on Kemp’s ridley sea turtles, which numbered at only 1,200 in the 1970s. After protections were put in place by the U.S and Mexico, including changes to fishing procedures and protection for nesting sites, the population has grown by up to 15 percent annually.5

The study also pointed to several other conservation efforts that have had positive outcomes, including international conservation agreements such as CITES, which prohibits trade in sea turtle products, noting that long-term localized efforts are also effective:6

“Encouraging trends of sea turtle population resilience and recovery often reflect the long-standing efforts of conservation programs, with even simple measures helping to boost population recovery. For example, efforts to limit the harvesting of sea turtles and their eggs at Tortuguero, Costa Rica date back to the late 1950s.

In the Hawaiian Archipelago, the recovery of green turtles was facilitated by the protection of turtles at both nesting beaches and foraging habitats through the enforcement of the U.S. Endangered Species Act dating back to 1978. Similarly, strong recovery patterns have been detected for leatherback and green turtles nesting on the index beaches of Florida, following the implementation of more than 35 years of monitoring and conservation effort.”

Sea Turtles’ Perilous Journey to the Sea

Sea turtles can grow to be 2,000 pounds and may live up to 100 years. Once adults, they face few natural predators (among them are sharks, orcas occasionally and humans), but their first days on the planet are extremely perilous. Female sea turtles travel back to their place of birth to lay eggs (spending hours to travel across the sand, dig a hole, lay the eggs and cover them with sand), which hatch after about 60 days.

The hatchlings are just over 2 inches long when they must make their way across the beach and into the sea. Many hazards stand in their way and many fall prey to birds or crabs, or once in the sea, fish, octopus and other marine life.

Even ridges left on beaches from vehicles pose an obstacle, as if the turtle falls into a deep enough rut, it has no way of climbing back out. According to international charitable organization the Turtle Foundation, “Only about one or two out of 1,000 hatchlings survive and grow into an adult turtle.”7

As adults, humankind poses one of the biggest threats to sea turtles. Aside from ending up as bycatch of commercial fisheries, artificial lights on beaches from bars, hotels, restaurants and houses may lure hatchlings in the wrong direction, preventing them from ever reaching the sea. Other man-made threats to sea turtles include, according to the Turtle Foundation:8

  • Hunting and egg exploitation, as in some areas of the world turtles are hunted for meat, shells and eggs
  • Tourism and coastal development, which is destroying sea turtle habitat and disturbing nesting sites
  • Boat strikes, which can injure or kill the turtles
  • Pollution, especially plastic pollution; turtles may confuse plastic bags with one of their favorite foods, jellyfish, leading to fatal digestive-system blockages

Sea Turtles Play an Important Role in Marine and Beach/Dune Ecosystems

Like all creatures, sea turtles play an irreplaceable role in their local ecosystems, both on land and in the sea. On land, sea turtle eggshells, as well as eggs that don’t hatch, provide valuable nutrients to dune vegetation. In the sea, sea turtles not only act as a food source to sharks but also graze on sea grass (particularly green sea turtles).

By helping to keep the sea grass short, sea turtles help beds of sea grass to flourish, which, like sea turtles, have been declining in recent decades. As the Sea Turtle Conservancy pointed out:9

“Sea grass beds are important because they provide breeding and developmental grounds for many species of fish, shellfish and crustaceans. Without sea grass beds, many marine species humans harvest would be lost, as would the lower levels of the food chain. The reactions could result in many more marine species being lost and eventually impacting humans.

So if sea turtles go extinct, there would be a serious decline in sea grass beds and a decline in all the other species dependent upon the grass beds for survival. All parts of an ecosystem are important, if you lose one, the rest will eventually follow.”

While the featured study reported promising increases in sea turtle populations, it’s important to note that sea turtles are still endangered, some critically, and the researchers noted that their time series may be too short to identify longer-term trends. As a result, the findings “highlight the importance of continued conservation and monitoring efforts” to ensure this sea turtle conservation story has a happy ending.10