Cat Ba National Park, established in 1986, currently manages 17,362.96 ha and is one of the most unique nature reserves in Vietnam. It is a rare convergence point between tropical and marine ecosystems, with outstanding values in natural landscapes, biodiversity, and ecosystem diversity.

Hidden beneath the clear blue waters of Cat Ba is a vibrant and colorful world of coral reefs. They are not only visually striking limestone structures but also the backbone of the marine ecosystem, described by scientists as "the lungs of the ocean”. They create vast natural "nurseries,” playing a key role in breeding and dispersing aquatic species, nurturing abundance throughout the northern seas of Vietnam.

According to statistics from the Institute of Marine Research, the waters of Cat Ba are home to approximately 84 species of hard corals, belonging to 33 genera and 11 families. The coral species composition is quite rich and diverse, forming a unique fringing reef structure. Although not as brightly colored or diverse as the coral reefs in southern waters, Cat Ba's corals possess a distinct beauty, quiet and majestic, typical of the Gulf of Tonkin. These coral reefs provide a habitat for countless fish and colorful marine organisms, creating a vibrant underwater panorama.

However, this majestic scene is gradually fading, giving way to gray patches of degradation. Over the past 15 years, coastal research programs in the Cat Ba archipelago have continuously recorded a decline in coral reefs.

According to the 2022 monitoring results at three sites (Ba Dinh, Van Ta, Gio Cung) within Cat Ba National Park, a total of 37 coral species belonging to 9 families were identified. The hard coral species composition at each surveyed area was relatively low, with the highest at Van Ta (26 species), followed by Gio Cung (15) and Ba Dinh (14). This alarming decline in coverage, area, and species numbers serves as an urgent warning that the health of Cat Ba’s marine ecosystem is under serious threat.

The degradation of Cat Ba’s coral reefs is not a random phenomenon but the result of a series of negative factors that intertwine human activities with harsh natural changes.

According to Dr. Nguyen Dang Ngai from the Institute of Marine Resources and Environment, several major human-induced factors are eroding the "lungs of the ocean”.

First, unsustainable fishing and aquaculture are the primary causes. Destructive practices such as blast fishing and electric fishing not only deplete marine resources but also directly destroy coral structures. Trawlers, although banned, still leave scars on the coral beds.

Unregulated and excessive aquaculture produces large amounts of organic waste, leftover feed, and antibiotics. These settle on the seabed, causing eutrophication, toxic algal blooms, reduced oxygen, and increased turbidity, which block photosynthesis, leading to coral bleaching and death.

Unsustainable tourism also contributes significantly. Boats moored indiscriminately and anchors dropped directly on reefs cause physical damage. Tourists who touch or break corals, or who discard plastic waste into the sea, cause both direct and indirect harm. Untreated sewage from tourist boats, coastal restaurants, and hotels, when discharged into the sea, further increases localized pollution.

Pollution from the mainland and industrial development are other serious threats. Urban and industrial wastewater from nearby residential areas and factories, if not properly treated, can flow into the sea and become toxic to corals. The expansion of logistics services and modern industrial complexes at Lach Huyen creates pressure through habitat loss, increased turbidity from dredging and construction, and noise pollution, all of which negatively affect coral growth.

In addition to human impacts, Cat Ba’s coral reefs also face risks from climate change and natural factors. Climate change causes coral bleaching due to rising sea temperatures. Symbiotic algae (zooxanthellae), which provide color and energy, are expelled, leaving corals deprived of nutrients and leading to death if the condition persists. At the same time, the absorption of carbon dioxide (CO2) increases ocean acidity, directly affecting the corals’ ability to form calcium carbonate skeletons, weakening them and hindering growth.

Extreme weather and natural disasters also cause severe damage. The Cat Ba archipelago experiences multiple storms and tropical depressions each year. Strong storms generate high waves and strong currents, which directly break coral structures or bury them under sediment. Specifically, Storm No. 3 (Yagi) in 2024 caused the loss of 40 mooring buoys installed in 2013 and 5 installed in 2023 within Cat Ba National Park, demonstrating severe destruction of the hard coral structures on the seabed.

Finally, corals' slow and limited recovery capacity is a major challenge. Corals are organisms with very slow growth rates. A damaged or destroyed reef can take decades or even hundreds of years to recover naturally. This makes restoration efforts difficult, costly, and requires long-term, persistent commitment.

In response to the alarming degradation of coral reefs, the Ministry of Agriculture and Environment, the Hai Phong People’s Committee, and Cat Ba National Park have implemented a series of coordinated, multi-layered measures. These efforts, supported by scientific organizations and domestic and international enterprises, are gradually zoning, monitoring, and restoring the coral reef ecosystem, the "lungs of the ocean" of Cat Ba.

To minimize human impact, one of the top priorities is establishing strict protection zones. Since 2023, the International Union for Conservation of Nature (IUCN), in collaboration with Cat Ba National Park and TH Food Chain Joint Stock Company (TH Group), has installed 23 mooring buoys for coral reef ecological zoning. Made from durable composite materials with bright colors, these buoys have been deployed in key areas such as Van Ta, Ba Dinh, Gio Cung, and Cat Dua, covering approximately 34 ha of sea surface.

These buoys serve a dual purpose. First, they serve as visual warning markers, helping fishing and tourism vessels easily identify the boundaries of protected areas and avoid navigation or mooring within prohibited zones. The words "CORAL REEF PROTECTION AREA – NO ENTRY" are clearly printed as a strict reminder. Second, clear zoning facilitates the work of rangers and authorities in patrolling and inspections, enabling timely detection, prevention, and handling of intentional violations, such as harvesting, fishing, or coral damage.

Rangers at Cat Ba National Park play a frontline role. The ranger unit, consisting of 60 members divided into 13 stations, conducts continuous patrols for 15 to 20 days each month. Advanced GPS devices are also used to monitor all activities within the managed areas, ensuring regular presence and rapid response capabilities.

"The park leadership requires underwater ranger stations to increase patrol and inspection frequency to detect and prevent intentional intrusions into prohibited areas promptly”, Mr. Nguyen Van Thiu added.

To provide accurate data and evaluate the effectiveness of conservation measures, scientific monitoring programs are conducted regularly and systematically. From 2021 to 2022, the Vietnam Business for Environment Alliance (VB4E), IUCN, and Cat Ba National Park carried out coral reef monitoring programs in three key areas (Van Ta, Ba Dinh, Gio Cung).

The two-year monitoring results show that average coral cover tends to increase slowly, and coral species diversity remains low, with a total of 37 species across 9 families. Based on these results, Cat Ba National Park has proposed more effective management and conservation measures, focusing on protecting existing species and creating favorable conditions for their development.

In addition, restoration through coral cultivation is being researched and tested for heavily damaged or bleached reefs due to negative impacts. However, this process requires significant effort and time, with major technical, cost, and survival rate challenges.

Dr. Hoang Dinh Chieu, Head of the Marine Conservation Research Department (Institute of Marine Research, Ministry of Agriculture and Environment), stated that aquaculture in Cat Ba is now well planned, with designated areas, no longer scattered as before. The city has implemented a detailed planning project for the Cat Ba – Long Chau marine protected area. This is a significant effort to conserve biodiversity and the coral reef ecosystem in the Hai Phong waters.

Additionally, numerous programs for coral restoration and artificial coral breeding are being implemented, contributing to the recovery of coral reef ecosystems and the regeneration of seafood resources, helping to stabilize the livelihoods of local fishermen. The project to transform the city’s fishing industry is also gradually reducing pressure on marine resources.

"Hai Phong city is reviewing and approving the detailed planning for the Cat Ba – Long Chau marine protected area (national plan covering an estimated 25,000 ha). Both areas have high biodiversity and many important marine habitats”, Dr. Hoang Dinh Chieu shared.

Although many efforts have been made and initial results are encouraging (with coral reefs showing signs of recovery and regrowth), coral conservation in Cat Ba still faces numerous challenges, requiring a strategic vision and long-term, sustainable cooperation.

Challenges related to financial and material resources are significant, as purchasing and installing the mooring buoy system involves very high costs. Mr. Nguyen Van Thiu stated, "These buoys are made of composite material. Each buoy costs VND 5 million (equivalent to USD 190.1), and with the mooring system, installation costs exceed VND 10 million (equivalent to USD 380.2) per buoy”. With an estimated total coral reef area of about 85 ha and a protected zone covering 34 ha, the 23 buoys remain very limited, necessitating additional funding sources.

Damage from natural disasters and maintenance are other concerns. The Cat Ba archipelago experiences multiple storms and tropical depressions annually. During Storm No. 3 (Yagi) in early September 2024, Cat Ba National Park lost all 40 mooring buoys installed in 2013 and 5 buoys installed in 2023. This loss highlights the vulnerability of conservation infrastructure to extreme weather. The marine environment, including saltwater and organisms such as oysters and clams, can cause corrosion and damage. Therefore, the mooring system requires inspection and maintenance at least once a year. To address this, the Park plans to mobilize teams to retrieve the buoys during major storms to protect them better.

Human resource limitations and coordination challenges remain significant. Despite having 60 rangers, patrolling and effectively preventing all damaging activities across the 17,362.96 ha managed area is a major challenge, requiring closer collaboration between authorities and the community.

Coral reef conservation in Cat Ba is not only the responsibility of the National Park or scientists but a collective endeavor, requiring the commitment of society as a whole, particularly strong cooperation between the government, businesses, and communities.

The involvement of the business sector in nature conservation has become a bright spot, reflecting social responsibility and a vision for sustainable development. TH Group, through TH Food Chain Joint Stock Company (THFC), is a prominent example. The group is a founding member of the Vietnam Business for Environment Alliance (VB4E) established by IUCN in 2021.

TH Group has sponsored coral conservation projects at Cat Ba National Park from 2021 to 2024. When Storm No. 3 damaged the mooring buoys, TH Group decided to donate an additional five buoys and accompanying equipment, raising the total number of buoys supported by VB4E to 17. This is a positive signal, showing that sustainable development is not just a slogan but a tangible action, providing critical financial and technical resources for conservation.

At the local level, Hai Phong city has established the Steering Committee for Managing the World Natural Heritage of Ha Long Bay – Cat Ba Archipelago, focusing on ecosystem protection at Cat Ba National Park.

Biodiversity conservation, especially of coral reef ecosystems, has helped Cat Ba National Park gain recognition on the global nature conservation map. Thanks to these efforts, the Park is fostering a rich diversity of terrestrial and marine flora and fauna. Notably, the population of Cat Ba langurs, one of the 25 most endangered primates in the world, has increased from around 40 individuals in 2000 to 92 today, serving as a living testament to the effectiveness of conservation work.

Although Cat Ba’s coral reefs are not as vividly colored as those in southern waters, they are among the most beautiful reefs, representative of the Gulf of Tonkin. Therefore, the journey to conserve Cat Ba’s "lungs of the ocean" is a race against time, demanding persistence, scientific investment, and, above all, the collective commitment of the government, businesses, communities, and individuals. Only then can the majestic beauty of Cat Ba be preserved, not only for today’s generation but also for the future, deserving its title as a World Natural Heritage site and a source of pride for Vietnam.