Quang Tri steps up effort to preserve giant coxcomb oyster

Despite its precise scientific name, local fishermen commonly refer to the giant coxcomb oyster as the “king oyster,” signifying its top-notch quality, suitable for crafting delicious dishes reserved for special occasions. Perhaps for this reason, this oyster species is extensively sought after and harvested in the Con Co Island Marine Reserve. In this context, conservation and management, coupled with sustainable harvesting of the giant coxcomb oyster, become imperative.

Fishermen on Con Co Island engage in harvesting giant coxcomb oysters. - Photo: BQLKBT

The island’s specialty

For many tourists, visiting Con Co Island without savoring the giant coxcomb oyster dish is considered incomplete. The scientific name for the giant coxcomb oyster is Hyotissa hyotis Linnaeus, 1758. However, local fishermen commonly refer to this species as the “king oyster,” emphasizing its top-quality suitable for preparing delicious, nutrient-rich meals that many wish to experience at least once.

Driven by the demand from tourists, the harvesting of giant coxcomb oysters in the Con Co Island Marine Reserve is quite prevalent. Typically, fishermen engage in harvesting this species from March to September each year. The primary harvesting area is the administrative service zone within the Con Co Island Marine Reserve. To harvest giant coxcomb oysters, locals often use small wooden boats, composite boats, equipped with 8-12 HP diesel engines to reach the habitats of this oyster species. The giant coxcomb oysters are usually harvested manually or using tools such as small hammers, chisels, or diving knives.

According to information from the Management Board of the Con Co Island Marine Reserve, giant coxcomb oysters are primarily harvested to meet the culinary demands on Con Co Island. Additionally, a small portion of this oyster species is transported to the mainland for consumption as gifts. In 2023, the estimated harvest of giant coxcomb oysters was around 8,000 individuals, equivalent to approximately 16 tons. Each live oyster is sold by fishermen to island restaurants at prices ranging from VND25,000 to VND45,000 (US$1-1.83) per oyster. After purchasing from fishermen, processing and dining establishments serve tourists at prices ranging from VND70,000 to 100,000 ($2.84-4.06) per live oyster, constituting over 50% of the set meal prices for tourists.

Giant coxcomb oysters harvested in the Con Co Island Marine Conservation Area are of significant size and hold high economic value. - Photo: T.L

Focusing on conservation effort

Leadership at the Management Board of the Con Co Island Marine Reserve emphasizes that among the distributed species in the reserve, giant coxcomb oysters are highly distinctive and economically valuable.

This bivalve mollusk belongs to the class of soft-bodied animals, with two shell halves, and has a large body size. The meat of the giant coxcomb oyster is highly nutritious, with estimated protein content in the meat ranging from 67.8% to 89.6%. This is the main reason why many people seek to purchase it, despite its relatively high price.

From 2017 to the present, giant coxcomb oysters have been extensively harvested for the preparation of various dishes catering to tourists visiting Con Co Island. The increasing demand for this oyster species has led to an expansion of harvesting areas by local fishermen. This has created significant pressure on the management and conservation efforts, potentially leading to the depletion of giant coxcomb oysters. Without timely management measures, this species could become scarce or even face extinction.

Facing this reality, the development of management and sustainable harvesting solutions for giant coxcomb oysters in the Con Co Island Marine Reserve is crucial. However, it’s noteworthy that, to date, there has been limited research and surveys on giant coxcomb oysters in the reserve, especially regarding their harvesting status and distribution. Therefore, relevant authorities face challenges in assessing the resource status, including density, reserves, harvest volumes, distribution patterns, etc., for giant coxcomb oysters.

Officials from the Management Board of the Con Co Island Marine Conservation Area inspect the status of giant coxcomb oysters, coral, and various seabed organisms. - Photo: BQLKBT

Recognizing this issue, starting from January 2023, Deputy Director of the Management Board of the Con Co Island Marine Reserve, Tran Khuong Canh, and his colleagues have conducted a research project specifically on giant coxcomb oysters. The study focuses on evaluating the distribution and harvesting status of this oyster species.

The research team found that the density of giant coxcomb oysters in the marine areas managed by the Con Co Island Marine Reserve is relatively high, averaging 0.13 individuals/m2. Harvested giant coxcomb oysters in the marine areas managed by the reserve have an average weight of approximately 1.94 kg/individual and an average length of around 16.7 cm.

In each functional zone, the density distribution of giant coxcomb oysters tends to increase with depth. Rock and coral substrates are suitable for giant coxcomb oysters. The estimated number of giant coxcomb oysters with shell lengths of 5 cm and above distributed in the functional zones of the Con Co Island Marine Reserve in July 2023 is over 5 million individuals.

Establishing harvesting team a crucial solution

As the direct executor of the study, Deputy Director Canh emphasized that the current level of giant coxcomb oyster harvesting to meet culinary demands on Con Co Island remains within acceptable limits compared to the estimated reserves. However, recently, the number of fishermen harvesting this species for consumption on the mainland has been on the rise. This has created various problems, with the most noticeable being the reduction of giant coxcomb oyster resources on Con Co Island and the diminishing unique characteristics of this species on the island.

To address this situation, according to Cnh, the involvement of relevant authorities at all levels is crucial. In this regard, the Management Board of the Con Co Island Marine Reserve and the People’s Committee of Con Co Island need to coordinate effectively to integrate the conservation, management, and sustainable harvesting of giant coxcomb oysters. Establishing a joint management and harvesting team for this oyster species can be considered a crucial solution.

Participating in this team, members will be given the opportunity to harvest oysters to meet the culinary needs of tourists directly on the island. However, they must commit to strictly adhering to and rigorously implementing regulations regarding the maximum allowable harvest of giant coxcomb oysters per year, permitted harvesting areas, harvesting seasons, fishing gear, and harvesting methods.

Relevant authorities at all levels need to unify their views to minimize the harvesting of giant coxcomb oysters for consumption on the mainland because, invisibly, this practice rapidly depletes resources and diminishes the unique characteristics of Con Co Island.

If implemented seriously, it is believed that these specific regulations will help giant coxcomb oysters grow and develop sustainably in the Con Co Island Marine Reserve, contributing to the conservation of biological diversity and rare genetic resources. Consequently, sustainably harvested giant coxcomb oysters can play a role in promoting the development of the tourism sector in Con Co Island.

The Con Co Island Marine Reserve spans a total area of 4,532 hectares, comprising 534 hectares of strictly protected zones, 1,392 hectares for ecological restoration, and 2,376 hectares designated for development. Additionally, there is a community development area covering 230 hectares (the surface area of the island) and a conservation belt surrounding the reserve. Recognized as one of Vietnam’s highly diverse marine ecosystems, it features typical tropical marine habitats such as coral reefs, seaweed beds, and various fish species.

Through surveys conducted in the Con Co Island Marine Reserve, a total of 953 marine species have been documented, including 133 species of marine plants, 97 species of marine animals, 136 coral species (comprising 113 hard coral species and 23 soft coral species), 182 reef fish species, and 302 benthic species (including 186 soft-bodied animals, 49 echinoderms, 48 arthropods, and 19 segmented worms). Additionally, there are 96 species of seaweed, one seagrass species, and six mangrove plant species. Among these, several rare and economically valuable seafood species are present, such as lobster, abalone, sea cucumber, sawtooth oyster, green-lipped mussel, scallop, tuna, mackerel, crab, squid, and horn coral.

Tay Long - Ngoc Mai