Climate Change and Indonesian Sea Cucumber Fisheries: What Ocean Warming Means for Supply

In the summer of 2018, something unusual happened in the sea cucumber pond farms of northern China. Water temperatures in the ponds climbed to between 28 and 33 degrees Celsius, well above the threshold that the species being cultivated, Apostichopus japonicus, could tolerate without entering a state of metabolic dormancy. The animals stopped feeding, their digestive tracts began to atrophy, and mass mortality followed across thousands of hectares of aquaculture operations. The economic losses were substantial. The event was not a natural disaster in the traditional sense. It was a preview.

Climate change is already restructuring the conditions under which sea cucumbers live, feed, reproduce, and die across the Indo-Pacific. The changes are operating on different timescales and through different mechanisms for temperate and tropical species, for wild populations and aquaculture operations, and for the habitat systems that support sea cucumber populations. Understanding these mechanisms matters not as an exercise in environmental concern but as a practical supply chain planning requirement for any organization whose procurement depends on consistent access to sea cucumber from Indonesian and broader Indo-Pacific sources.

The Temperature Threshold Problem for Temperate Species

The Chinese sea cucumber aquaculture industry, which produces approximately 250,000 metric tons of Apostichopus japonicus annually and supplies a significant portion of global premium-grade dried sea cucumber, operates at the edge of a biological constraint that ocean warming is progressively tightening.

Once seawater temperature exceeds 28 degrees Celsius, Apostichopus japonicus undergoes aestivation, a state of dormancy during which sea cucumbers experience weight loss, degeneration of their digestive tracts, and a decrease in immunocompetence. This temperature threshold is not a worst-case scenario. It is a documented biological reality for the species that dominates global sea cucumber aquaculture production.

During aestivation, which can last up to four months, sea cucumbers exhibit little movement and depressed metabolic activity. The aestivation duration is expected to increase as global warming continues, with projections showing meaningful extension of the dormancy period even under moderate warming scenarios.

The 2018 mass mortality event in Chinese pond farms was not an isolated incident. It was the most severe manifestation of a pattern that has been observed with increasing frequency as summer temperatures in northern Chinese coastal waters, historically within the comfortable range for A. japonicus growth, approach and exceed the aestivation and mortality thresholds documented in the research literature. For supply chain operators who rely on Chinese aquaculture production as their primary source of premium temperate sea cucumber, this pattern constitutes a systemic supply risk that is expected to intensify over the coming decades.

Tropical Species and Ocean Acidification: A Different Vulnerability

Tropical sea cucumber species from Indonesian waters face a different set of climate stressors than their temperate counterparts. Ocean warming affects them, but the most acute documented vulnerability for tropical species is to ocean acidification, particularly during early life stages.

Tropical and temperate holothurians are more vulnerable to temperature and pH changes than those from colder water environments. It is possible that in these areas, larval survival will decline by up to 50% in response to a reduction of 0.5 pH units. Such reduction in pH may trigger low intrinsic growth rates and affect the sustainability of the resource. A 50% decline in larval survival is not a marginal effect. It is a population-level impact that, sustained over years of progressive ocean acidification, would reduce recruitment into wild populations and slow the recovery of stocks that are already depleted from decades of harvesting pressure.

Research published in ISME Communications (Oxford Academic, 2025) examined gut microbial community plasticity as a climate resilience mechanism in sea cucumbers. Ocean acidification and ocean warming pose escalating threats to marine ecosystems, particularly to benthic organisms such as sea cucumbers that play pivotal roles in nutrient cycling and sediment health. The study found that gut microbial community plasticity functions as a climate shield mediating sea cucumber resilience to combined ocean acidification and warming stressors, with sea cucumbers demonstrating capacity to restructure their gut microbiome in response to climate stressors in ways that partially compensate for physiological stress.

This finding provides a degree of biological optimism: sea cucumbers are not entirely passive in the face of climate stressors. The gut microbiome plasticity documented in this research suggests that some populations may possess adaptive capacity that reduces their vulnerability to moderate climate change scenarios. But the research is explicit that this adaptive capacity has limits, and that under the more severe warming and acidification scenarios projected for the end of the century, the compensatory mechanisms are insufficient to prevent population-level impacts.

Coral Reef Bleaching and the Habitat Dimension

The climate change vulnerability of Indonesian sea cucumber supply does not operate only through direct physiological effects on sea cucumbers themselves. It operates equally through the degradation of the habitat systems on which commercially significant species depend.

Several of Indonesia's most commercially valuable sea cucumber species occupy reef-associated habitats. Holothuria fuscogilva inhabits sandy lagoon floors adjacent to reef systems. Thelenota ananas lives on reef slopes and passes. Stichopus herrmanni occurs on rubble and structured reef substrate. The health of these reef systems is directly relevant to the population viability of the species that inhabit them.

Between 2023 and early 2025, over 80% of the world's reefs experienced severe heat stress likely to induce coral bleaching, in what the National Oceanic and Atmospheric Administration concluded was the most widespread global bleaching event in recorded history. This fourth global bleaching event, which affected reefs across the Indo-Pacific including Indonesian waters, represents a habitat disruption of a scale and severity that has no precedent in the commercial history of Indonesian sea cucumber fisheries.

Research published in Science Advances on cumulative bleaching risk for the world's coral reefs found that reefs in the Coral Triangle and Southwest Pacific Ocean, which support the livelihoods and nutrition of local populations that rely heavily on these resources for subsistence fishing, are disproportionately threatened by anthropogenic climate change, with high risk of bleaching even under reduced warming pathways. The Coral Triangle, which sits at the geographic center of Indonesian sea cucumber production, is simultaneously the region of highest marine biodiversity and the region of highest cumulative bleaching risk under current climate projections.

Coral bleaching does not immediately eliminate sea cucumber populations from affected reef systems. Sea cucumbers are more tolerant of thermal stress than the corals whose structural decline degrades their habitat. But the loss of reef structure, the reduction in reef-associated productivity, and the changes in sediment composition and availability that follow sustained bleaching events progressively reduce the habitat quality available to reef-associated sea cucumber species. The effects manifest on a timescale of years to decades rather than in the immediate aftermath of a bleaching event.

Seagrass and Soft-Bottom Habitat: The Sandfish Dimension

For Holothuria scabra, the species most important to Indonesian export trade, the primary climate vulnerability is not coral bleaching but the degradation of seagrass habitats, which provide both feeding substrate and shelter for adult sandfish and are critical nursery environments for juveniles.

Seagrass meadows in Indonesian coastal waters face multiple stressors that are exacerbated by climate change: higher water temperatures reduce the photosynthetic efficiency of seagrass at the upper end of the thermal tolerance range; increased storm intensity associated with ocean warming causes physical damage to seagrass beds; and the increased frequency of marine heatwaves causes direct seagrass die-off events of the type documented in Australia and elsewhere in the Indo-Pacific in recent years.

The interaction between climate-driven seagrass degradation and the existing pressure on H. scabra populations from decades of intensive harvesting creates a compounding risk: a species whose populations are already depleted is simultaneously facing degradation of the habitat conditions that would support its recovery. Sea ranching programs that release juvenile sandfish into seagrass areas depend on the availability of intact seagrass habitat to provide the feeding substrate and shelter that determine post-release survival. As climate change progressively reduces seagrass coverage in Indonesian coastal waters, the ecological foundation for sandfish recovery programs is itself under pressure.

What the Research Literature's Most Recent Assessment Says

The 2025 Annual Review of Marine Science study by Mercier, Purcell, Montgomery, Kinch, Byrne, and Hamel, which provided the most comprehensive assessment of global sea cucumber fisheries status in recent years, addresses climate change explicitly within its broader analysis of threats to global sea cucumber populations. The study's framing of the situation as "perilous" reflects not just the current state of overfished wild stocks but the compounding effect of climate change on populations that are already operating below the density levels that would support natural recovery under stable environmental conditions.

The combination of documented population declines, habitat degradation from coral bleaching and seagrass loss, and the physiological vulnerabilities documented in laboratory and field research creates what the research literature describes as a scenario of compounding stressors. Each individual stressor, overfishing, ocean warming, ocean acidification, habitat loss, is serious in isolation. Their interaction produces outcomes that are more severe than any single stressor would generate independently.

Supply Chain Implications for Long-Term Procurement Planning

For supply chain operators with planning horizons extending beyond the immediate procurement cycle, the climate research literature points toward several concrete supply chain implications.

The geographic diversification of supply sources reduces exposure to the climate impacts that are most severe in specific regions. Chinese aquaculture production of Apostichopus japonicus faces increasing aestivation and mortality risk from summer temperature exceedances. Indonesian wild fisheries face reef bleaching and seagrass degradation. These are different risks operating in different geographies, and a supply chain that depends exclusively on either source carries concentrated climate exposure that a geographically diversified supply base reduces.

The investment in aquaculture and sea ranching programs that operate in climate-resilient locations, at depths less exposed to surface warming extremes, and with species whose temperature tolerance ranges are wider than A. japonicus, represents a supply security hedge against the worst-case climate scenarios. The species most commercially significant in Indonesian export trade, particularly tropical holothuriids like H. scabra, have temperature tolerance ranges that extend to higher maxima than temperate species, though they are not immune to the ocean acidification effects documented in the research literature.

The documentation infrastructure that climate resilience requires is not separate from the traceability infrastructure that regulatory compliance requires. Suppliers who can document harvest origin at the specific site level can also demonstrate whether product originates from climate-impacted areas or from more resilient locations. This documentation granularity will become increasingly relevant as institutional buyers with ESG commitments begin to incorporate climate risk into their supply chain assessments.

Sepanjang's direct operational presence across multiple Indonesian producing regions provides visibility into the habitat conditions and population dynamics that climate change is affecting at the local level. We welcome conversations with organizations seeking to understand the climate dimension of their Indonesian sea cucumber supply chain.

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Sepanjang — Indonesia's Specialty Ocean Products Co. Sourcing high-quality sea cucumber directly from Indonesian waters for over 20 years.

PT Sepanjang Laut Nusantara is an Indonesia's Specialty Ocean Products Co. specializing in Sea Cucumber, Seaweed, Abalone, and Seashell from Indonesia — for domestic and international B2B markets.

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