Seven Years of Data Raise the Alarm for Shui Hau: WWF-Hong Kong Releases Conservation Report and Hosts Science Forum to Build Consensus on Protecting Horseshoe Crabs and the Sandflat
However, overall clam density has declined precipitously by 65% since 2018, reflecting the current harvesting activity has exceeded sustainable levels. This poses an immediate threat to the sandflat ecosystem and directly jeopardises the survival of globally Endangered horseshoe crabs. The overall trend is deeply concerning, underscoring the urgent need to implement science-based conservation measures more urgent than ever.
These findings, collected through WWF's community-based conservation project, paint a complex picture of ecological stress and behavioural shifts along Shui Hau's coastline. While the sandflat continues to support significant number of juvenile horseshoe crabs, made up largely by the globally endangered Chinese Horseshoe Crab, its dependent habitat faces mounting pressure from escalating clam harvesting activities.
"Grounded in scientific evidence and informed by the expertise of ecologists, academics and conservation groups, this report presents a range of practical recommendations and calls on all sectors to take action for the sustainable future of Shui Hau." said Kelvin So, Oceans Conservation Manager at WWF-Hong Kong. "The science is clear: the ecological health of Shui Hau is at a tipping point, and we must act now to balance recreational use with the survival of threatened species."
Key Findings of the Report:
- Alarming Decline in Clam Populations: A 65% decline in overall clam density since 2018 signals that current harvesting pressure is ecologically unsustainable, placing enormous pressure on the ecosystem, with negative impact rippling through the entire food web.
- High Vulnerability of Horseshoe Crabs: Analysis reveals a 16% overlap between juvenile horseshoe crab habitat and recreational activity zones. Critically, over 70% of all horseshoe crab sightings were concentrated within just 6% of the sandflat. This extreme concentration means that even minor human disturbances—such as trampling and digging—can have a devastating impact on the population.
- Positive Behavioural Shift in Visitors: Despite a marked decline in clam numbers, the study observed a positive shift in visitor behaviour. A higher proportion of visitors now proactively avoid collecting immature clams, demonstrating that sustained public education efforts, including the distribution of the WWF-developed clam gauges are effectively driving noticeable compliance with sustainable harvesting.
- Technology-enabled Smart Conservation: The project successfully integrated advanced technologies, including AI-assisted clam size monitoring and real-time IoT spatial visitor tracking, to monitor the site. This "Smart Conservation" approach helps advance adaptive management, ensuring conservation strategies remain responsive to real-time ecological and visitor dynamics.
"In Hong Kong, there are few examples of ecologically important coastal sites where systematic monitoring has been conducted consistently across multiple years, generating the datasets needed for meaningful comparisons," said Professor Hui Tin-yan, Assistant Professor, Division of Science, Lingnan University, and a core member of the expert group. "WWF's seven years of continuous monitoring at Shui Hau Sandflat have generated a rare dataset that allows us to detect ecological changes, and to understand how human activities are influencing ecological conditions over time. These long-term data not only demonstrate Shui Hau's significant conservation value, but also provide an important foundation for developing future targeted management measures."
The report presents concrete conservation recommendations to the Hong Kong government and key stakeholders, advocating for an integrated management model that combines robust science, community participation, and statutory governance. Recent observations, including visitor surges during major holiday periods such as the Labour Day Golden Week, suggest that recreational pressure on Shui Hau is likely to increase further. WWF-Hong Kong believes there is now a golden opportunity to establish proactive management measures before ecological impacts become irreversible. WWF-Hong Kong urges the government to implement four key actions, including:
- Zoning Management Strategy: Designating a "Biodiversity Management Zone" to protect ecologically sensitive horseshoe crab and waterbird hotspots, while allowing controlled public access in a designated "Wise Use Zone".
- Visitor Capacity Management: Establishing a science-based daily visitor carrying capacity supported by real-time monitoring and alert systems to prevent overcrowding.
- Clam Harvesting Management: Introducing minimum size restrictions and quotas, alongside incentive mechanisms for voluntary clam release.
- Clamming Tool Management: Restricting the use of high-impact tools that disrupt sediment layers, while permitting only lower-impact tools like small hand rakes.
On the same day, WWF-Hong Kong hosted the "Shui Hau Sandflat Science and Conservation Forum," bringing together representatives from government advisory committees and departments, academia, conservation groups, environmental consultants and other stakeholders to share the latest research findings and practical experience on horseshoe crab conservation, intertidal ecology and the Shui Hau sandflat.
During the Forum, participants exchanged views on topics including horseshoe crab conservation, blue carbon ecosystems, visitor management and community engagement, discussing how cross-sector collaboration, grounded in scientific data, can drive the long-term conservation for the site going forward.
Speaking at the forum, Professor Cheung Siu-Gin, Associate Professor, Department of Chemistry, City University of Hong Kong, another member of the expert group, said: "One of the most distinctive features of the Shui Hau sandflat is that juvenile Chinese Horseshoe Crabs are not evenly distributed across the sandflat, but are instead highly concentrated in a small area of core habitats. This pattern is relatively rare among Hong Kong's coastal ecosystems. From a conservation perspective, effectively protecting these key areas brings significant benefits, conversely, even minor disturbance to these core habitats could have a far greater impact than we might expect."
" Our recommendations allow people to continue enjoy this secluded bay while critical biodiversity areas receive targeted protection they need." said Lydia Pang, Head of Oceans Conservation at WWF-Hong Kong. " Our long-term data clearly alerts us the risk of environmental degradation while guiding us to identify the most ecologically sensitive habitats. To ensure its long-term sustainability, we must move beyond voluntary measures. The government's Hong Kong Biodiversity Strategy and Action Plan (BSAP) 2035 provides a clear vision to enhance conservation of Shui Hau through area-based conservation. We stand ready to work closely with all stakeholders to safeguard this irreplaceable natural asset."
Link to download the completed report and event photos : https://wwf.hk/Shui-Hau-Report-Photos
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About WWF-Hong Kong
WWF is a leading global conservation organisation, with a network active in more than 100 countries. WWF's mission is to build a future in which humans live in harmony with nature. WWF-Hong Kong has been working since 1981 to deliver solutions for a living planet through conservation, footprint and education programmes, with the aim of transforming Hong Kong into Asia's most sustainable city. More details on wwf.org.hk.
