Sea Turtle Beach Monitoring on Koh Phra Thong

Every morning at sunrise, our conservation team and volunteers walk a 5-kilometer stretch of sand along the western shore of the island. Conducting regular sea turtle nesting beach monitoring early in the day is crucial: it allows us to identify fresh crawl tracks left during the night before the rising tide, wind, or human footprints wash them away.

Koh Phra Thong is recognized as one of the few remaining significant nesting grounds in Thailand for three endangered species: the Olive Ridley turtle (Lepidochelys olivacea), the Green turtle (Chelonia mydas), and the giant Leatherback turtle (Dermochelys coriacea).

 

Early Morning Patrols: Finding Tracks and Protecting Nests

Naucrates conducts long-term conservation monitoring in close coordination with local coastal communities, the Phuket Marine Biological Center (PMBC), and the Department of Marine and Coastal Resources (DMCR).

When our patrol team locates a turtle track emerging from the ocean, we follow the crawling path to determine whether an oviposition (nesting) occurred or if it was a non-nesting emergence (a “false crawl”). Finding a viable nest rewards years of dedication and provides critical hope for the future. Marine turtles exhibit natal homing—meaning females return to deposit their eggs on the very beaches where they hatched decades earlier, after reaching maturity between 15 and 30 years of age.

Daily morning surveys enable our team to:

• Identify and verify sea turtle nesting events immediately after nocturnal laying.
• Assess clutch safety against coastal erosion, high tides, and predator disturbance.
• Collect standardized biometric, GPS, and environmental nesting data for long-term population research in the Andaman Sea.
• Record any stranded or entangled marine wildlife requiring intervention.

Historical Nesting Trends on Koh Phra Thong

Historical data recorded by PMBC documented an 82% decline in Olive Ridley nesting between 1979 (238 clutches) and 1990 (42 clutches). Systematic surveys sustained by Naucrates since 1996 have mirrored this regional concern across the southwest coast of Thailand.

Historically, commercial and subsistence egg harvesting heavily impacted local populations across Phang Nga province, combined with the hunting of turtles for meat and tortoiseshell. Although egg poaching has been curtailed through legislation and sustained conservation presence, nesting density remains fragile, making continuous seasonal monitoring vital.

Encouragingly, recent seasons have seen notable nesting events, with regular clutches deposited by Green turtles and the return of Leatherback turtles after prolonged absences. Each verified nest confirms that these remote stretches of beach remain indispensable feeding and nesting refuges.

Graph 1: Sea turtle nests per season (1996-2024)

Major Threats to Coastal Nesting Habitats

Walking the beach every morning also allows our research team to assess anthropogenic pressures that compromise sea turtle survival:

Commercial and Nearshore Fisheries

Intensive offshore and nearshore fishing operations present severe hazards for gravid females and emerging hatchlings. Trawlers, gill nets, and untended coastal tangle nets set within shallow waters risk entangling and drowning turtles. Furthermore, extensive lighting arrays from offshore squid fishing fleets illuminate the horizon at night, creating light pollution that can disorient nesting females attempting to approach dark beaches or lead newly emerged hatchlings inland rather than toward the open sea.

Marine Debris Accumulation

Each monsoon and high tide cycle deposits substantial amounts of oceanic debris along the shoreline, including discarded fishing gear, ghost nets, styrofoam, and plastics. During our daily morning walks, volunteers regularly record and remove hazardous debris that could physically obstruct a female turtle hauling herself up the beach profile.

Coastal Degradation and Tourism Expansion

While Koh Phra Thong has retained much of its wild, natural coastline compared to heavily commercialized islands in Thailand, unmanaged development and beachside artificial lighting pose persistent risks. Protecting the natural coastal dunes and indigenous beach vegetation is essential to preserve the dark, undisturbed conditions sea turtles require to lay their eggs.

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