48 DECEMBER • WORLD AQUACULTURE • WWW.WAS.ORG as food availability and habitat characteristics further influence reproductive strategies and success. After spawning, early signs of growth become visible within one to two weeks, as small, circular marks known locally as ‘kapit’ appear on the planted oyster shells (Figure 3). These kapit, often referred to as oyster seeds, gradually develop into the spat stage, where it’s common for several young oysters to attach to a single piece of substrate. It’s only after reaching this spat stage that harvesting is considered. A waiting period of three to six months is oftentimes necessary before oyster harvests reach substantial levels. In this region, planting typically occurs between August and October, and this allows harvests to peak during the summer months of March to April. Thus, peak harvest levels typically occur just before or at the very start of the spatting season. Harvesting is typically done by retrieving the hanging cultch lines, with larger oysters separated for market selling and smaller ones returned to bamboo trays for further growth. Harvested oysters are then submerged, cleaned, and packed into gunny sacks, bamboo baskets, or kaing, with each bamboo basket holding approximately 40 kilograms of fresh oysters. The preferred marketable size ranges from 6.0 to 12.5 cm in length (Bureau of Fisheries and Aquatic Resources 2022). Several environmental factors, including salinity, water levels, intensity of tides, and temperature, play a significant role in oyster growth and overall production. Under favorable circumstances, production yields can reach between 8 to 12 metric tons per hectare. For small-scale operations, a family-managed growing area of about 2,500 square meters is considered an ideal and practical livelihood project for beginners (Bureau of Fisheries and Aquatic Resources 2022). Oyster farming is a significant driver of local economies in the Philippines, supporting livelihoods across the value chain from production to market. With over 7,000 islands and extensive coastlines, the country is uniquely positioned to benefit from this industry. Oyster cultivation fosters job creation, diversifies income, enhances food security, and contributes to long-term community sustainability. In 2020, the Philippines produced over 53,000 metric tons of oysters, valued at approximately 1 billion pesos or $20.13 million USD ((Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development, n.d.). Among the regions benefiting most from oyster farming is Bulacan, the country’s leading oyster producer. Its communities rely heavily on the industry for economic stability, with Bulacan contributing most of the national oyster output. In comparison, other top-producing provinces such as Capiz and Negros Occidental generate significantly lower volumes of 8,000 and 1,400 metric tons respectively (Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development, n.d.). In Ilocos Sur, oyster farming remains predominantly smallscale and family-run. Most growers operate on plots around 30 square meters, cultivating between 1,000 and 2,000 oyster hangings. Production is influenced by the availability of spatted hangings, while prices fluctuate seasonally rising during summer and Christmas. Farmers earn an average of $103 to $309 USD per cropping cycle (Domingo et al. 2021). According to farmers, the peak season for oyster demand occurs between March and April, coinciding with the Lenten season. During this time, many Filipino devotees, who strictly observe the traditional customs in Lent, refrain from consuming meat and seafood becomes a preferred alternative. Oyster farming in Pamawaran, Malolos and Bulacan has been a thriving industry for generations. Passed down from grandparents to their offspring, the local oyster farming practices and customs ensure a continuous cycle of livelihood for coastal communities. The region, which is characterized as a vast river system connected to the open sea, has long been a hub for aquaculture. Beyond oyster farming, the area is also home to fishing zones, salt fields, and mangroves that attract tourists, particularly during high tides. Between Tides and Trials: The Battle for Survival Despite its longstanding success, oyster farming in Pamawaran (Figure 4) is now facing multiple threats. One of the most pressing concerns is rapid industrialization. The construction of a new airport in Bulakan, which is just 42 kilometers away from the farms, poses a risk to the delicate coastal ecosystem. Additionally, flood control programs have disrupted the farmers’ traditional transport routes, and this has forced them to adjust when and how they transfer their harvests. The effects of rapid industrialization and associated anthropogenic activities on these ecosystems are also not unique to Pamawaran, and a lot of research studies in other areas which pertain to the degradation or even extinction of entire oyster communities serve as warnings to the oyster farming communities in Pamawaran if these issues cannot be addressed effectively. For instance, in one study, a fossil oyster bed consisting of the European flat oyster (Ostrea edulis) was recently found in the island of Helgoland, Germany, and its demise, which happened over 1,300 years ago, was likely the result of deteriorating habitat conditions and increased sedimentation driven by the widespread conversion of European forest cover into meadows and arable land (Sander et al. 2021). Anthropogenic activity has important ramifications on the health of consumers as well. In recent years, studies have shown that these oysters are absorbing increased levels of contaminants and pollutants from their environment, and these can easily be transferred to consumers if oysters are not managed properly. In Bacoor Bay, Cavite, microplastics, with an average quantity of 0.42 items per gram of oyster and an average size of 1.26 mm, were discovered in the soft tissues of Magallana bilineata or the slipper oyster, which is arguably the most common oyster in the Philippines (Insigne et al. 2022). Microplastic absorption is also common in Cañacao Bay, Cavite (Obanan et al. 2020). And in Capiz Province, Western Visayas, high levels of fecal coliforms in the water, as well as high levels of E. coli within the bodies of the slipper oysters themselves, were reported (Pakingking et al. 2022). Adherence to microbiological standards for fecal coliforms in shellfish-growing waters is critical to public health protection. Regulatory agencies such as the Philippine National Standards – Bureau of Agriculture and Fisheries Product Standards (PNS-BAFPS, 2011) and the European Commission (2007) have established a maximum permissible limit of less than 230 MPN per 100 mL. Exceeding this threshold poses substantial health risks, as high levels of fecal coliforms often indicate contamination with pathogenic microorganisms (Jones 2009). Vulnerable populations,
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