Researchers conducting a 14-month study in Indonesia’s Dampier Strait region documented 1,191 sightings of the Raja Ampat epaulette shark. The rare species uses its fins to walk across the seafloor, displays extreme site fidelity, and rarely ventures more than a few hundred meters from its home waters.
When people picture sharks, they usually imagine sleek predators slicing effortlessly through the open ocean.
Endemic to the waters surrounding Indonesia’s Raja Ampat Archipelago and found nowhere else on Earth, this small bamboo shark species lives in a celebrated marine biodiversity hotspot. Despite that status, scientists knew surprisingly little about its daily movements, growth, and habitat use until a comprehensive new study shed light on its biology and ecology.
Nighttime Surveys Reveal High Population Densities in Dampier Strait
Over a 14-month period, researchers carried out 64 nighttime surveys across six distinct locations within the Dampier Strait region of Raja Ampat. Armed with flashlights and headlamps, the team scoured shallow reef flats, sandy areas, mangroves, and seagrass meadows during low tide.
That fieldwork yielded an expansive dataset featuring 1,191 shark sightings representing 736 unique individuals. According to the study, relative population densities ranged from 333 to 2,462 individuals per square kilometer, marking some of the highest densities ever recorded for any species within the walking shark genus Hemiscyllium
. In hotspots around Arborek Island and Sawinggrai, the sharks appeared remarkably common.
Extreme Homebodies Face a Tough Conservation Paradox
Those robust numbers offer some reassurance for a species listed as Near Threatened, but their geographic reality introduces a sharp conservation dilemma. Unlike larger shark species capable of migrating hundreds or thousands of kilometers, Raja Ampat epaulette sharks are literal homebodies with an extremely limited geographic range.
During the research period, field teams re-encountered 256 individual sharks—some more than a year after their initial tagging. Not a single shark was observed moving between the different study sites, and even within specific sites, movement was minimal. The greatest net displacement recorded for any individual was just 475 meters, with most spending their entire lives across much tighter areas.
This strict site fidelity creates a distinct paradox. If local coastal habitats stay healthy, the resident sharks can thrive locally. If those same environments suffer damage, however, the sharks have few options.
Ontogenetic Habitat Partitioning and Nursery Reefs
While the majority of total shark sightings occurred in seagrass meadows, the population’s age structure revealed a clear division across life stages. Coral reef habitats contained a disproportionately high concentration of young sharks, with nearly 70 percent of individuals observed there classified as immature.
Conversely, seagrass beds and sandy zones hosted larger shares of adult sharks. This pattern points to ontogenetic habitat partitioning, where animals utilize different environments as they age. Coral reefs act as protective nurseries where juvenile sharks grow protected by complex reef structures before migrating to open habitats as adults. Protecting mature sharks alone will fail if these interconnected juvenile nursery grounds disappear.
Growth Rates, Seasonality, and Growing Pressures
The study also documented key biological traits, finding a significantly female-biased population where females slightly outnumbered males. Recorded body lengths spanned from just under 8 inches to 29.5 inches, equivalent to 20 centimeters to 75 centimeters. Both sexes reached sexual maturity at almost identical sizes, hovering around 22 inches or 56.5 centimeters.
Young sharks experienced much faster growth than older individuals, averaging nearly 3 inches or 8 centimeters per year compared to less than 1.2 inches annually in mature sharks. These growth rates showed distinct seasonal shifts, likely driven by monsoon-driven oceanographic changes across Raja Ampat.
Although early maturity and rapid youth growth initially suggest resilience, the Indonesian speckled carpetshark evolved less than two million years ago and remains confined to a narrow strip of the Indonesian archipelago. Because they rely heavily on shallow coastal waters, these walking sharks face mounting pressure from tourism expansion, habitat degradation, pollution, and climate change.
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