Green Turtles are Nesting Less Frequently along the Southern Coast of Java

The nesting activity of green turtles (Chelonia mydas), one of the protected and endangered sea turtle species, is showing a declining trend at Sindangkerta Beach, Tasikmalaya Regency, West Java. Recent scientific research data reveal a decrease in the number of turtles coming ashore to nest as well as a reduction in the number of eggs produced during the 2010–2017 observation period. The decline has been linked to changes in coastal environmental conditions and increasing pressure from human activities around the beach area.

A study titled Assessment of Green Turtle Nesting under Environmental Pressure at Sindangkerta Beach, West Java, Indonesia, January 2026 analyzed time-series data on turtle landings and egg production over seven years. The analysis shows that the number of green turtles nesting each year fluctuated between approximately 13 and 44 individuals. Meanwhile, annual egg production ranged from 1,129 to 3,422 eggs. Although the figures showed year-to-year variation, the trend toward the end of the observation period indicates a consistent decline in both nesting activity and egg production.

“Our data show that fewer green turtles are coming ashore to nest, reflecting a serious challenge to the survival of the local population,” said Mujiyanto, one of the lead researchers involved in the study. He emphasized that the decline is not merely seasonal fluctuation, but a signal of increasing environmental pressure on green turtle nesting habitats in the area.

Coastal Abrasion and Habitat Loss

The researchers identified coastal abrasion as a major factor contributing to the decline in green turtle nesting activity. Gradual shoreline erosion has reduced sandy areas that previously served as ideal sites for turtles to come ashore and lay eggs. These changes in beach morphology have diminished the availability of safe and suitable nesting space.

The situation is exacerbated by the loss of coastal vegetation. Natural vegetation such as sea pandanus, Terminalia, and Ipomoea, which help stabilize beach sand and create favorable microhabitats for nests, has continued to decline. As a result, turtle nests have become more vulnerable to extreme temperatures, flooding, and predator disturbance, ultimately lowering hatching success rates.

Additional pressure on green turtles comes from human activities along the coast. Increased artificial lighting at night and noise from nearby vehicle traffic are known to disrupt turtle orientation when they come ashore and when they return to the sea. Green turtles are highly sensitive to light and sound, and even minor disturbances can cause them to abandon nesting attempts.

Fishing activities and natural predators such as monitor lizards also threaten turtle eggs laid on the beach. Without adequate protection, nests are highly susceptible to damage and predation. “Green turtles are inherently sensitive to disturbance on nesting beaches. Noise, light, and degraded sand conditions can cause them to abandon nesting altogether,” Mujiyanto said.

Seasonal Patterns Still Persist

Despite the overall declining trend, the study found that green turtles at Sindangkerta Beach still exhibit relatively consistent seasonal nesting patterns. Nesting activity tends to increase during two main periods each year, from February to April and again from October to November. This pattern suggests that the reproductive cycle of green turtles remains synchronized with climate and seasonal conditions along the southern coast of Java, even as overall numbers continue to fall.

Green turtles are protected both internationally and nationally due to past hunting pressure, habitat degradation, and low natural hatching success. Declining nesting activity at key sites such as Sindangkerta Beach could further worsen the future status of green turtle populations if not addressed seriously.

Sindangkerta Wildlife Reserve remains one of the important green turtle conservation sites in West Java. Conservation measures include beach patrols during nesting seasons, nest protection, relocation of eggs to semi-natural hatcheries, and head-starting hatchlings before releasing them into the sea. However, experts say these efforts must be accompanied by broader coastal habitat protection.

“Turtle habitats are continually changing due to natural pressures and human activities. We need a more holistic approach that goes beyond nest protection to include beach habitat restoration and active involvement of local communities,” said Adriani Sri Nastiti, the other scientist of this study.

Researchers stress that long-term monitoring is essential to understand green turtle population dynamics at Sindangkerta Beach. Without appropriate intervention, the downward trend could threaten the survival of future turtle generations, especially with added risks from climate change, including sea-level rise and extreme weather events.

With increasingly robust scientific data, environmental advocates hope for stronger commitment from communities and policymakers to sustainably protect coastal habitats. Protecting green turtles is not only about conserving a single species, but also about safeguarding the balance of marine ecosystems that underpin the livelihoods of coastal communities in Indonesia. (Wage Erlangga)