:Draft:Cockles aquaculture in Thailand

Thailand's prefect natural source of blood cockles is in Phetchaburi Province,{{Cite web |title=เกร็ดความรู้ ทช. - กรมทรัพยากรทางทะเลและชายฝั่ง Department of Marine and Coastal Resources, Thailand |url=https://www.dmcr.go.th/detailAll/4449/nws/ |access-date=2025-04-17 |website=กรมทรัพยากรทางทะเลและชายฝั่ง กระทรวงทรัพยากรธรรมชาติและสิ่งแวดล้อม |language=TH}} with another long-established harvesting region in Bang Tabun, Phetchaburi. Meanwhile, blood cockles from Ao Ban Don in Surat Thani Province stretch back over 30 years to a period of local scarcity when hatchlings were imported from Malaysia and grown in Tha Chang.{{Cite web |last=ชนิดหอยแครง |title= |url=}}

Ao Ban Don in Surat Thani is perfect for blood cockle farming because of its large, nutrient-rich mudflats. To enhance their number, growers began converting old shrimp farms into cockle farms. These farms were primarily located in Samut Prakan, Samut Sakhon, Samut Songkhram, and Bang Khun Thian, and covered roughly 100,000 rai.

Previously, these sites were used for black tiger shrimp aquaculture, which involved pumping water into ponds. Depending on the season, the water may be highly saline (ideal for salt manufacturing) or completely fresh. Despite the ability to manage salinity levels via water gates, early attempts at blood cockle farming in these old shrimp ponds resulted in severe mortality rates.

Farmers eventually noticed that the pond beds had become harsh and released hydrogen sulfide gas, which contributed to the cockles' death.  They were first unaware of the specific cause, believing that blood cockles ate plankton such as mussels and oysters. In reality, blood cockles feed by sifting organic debris from surface dirt, much like mudskippers.

When too much organic waste from separating plankton accumulates on the pond bed, it might promote rapid development. To enhance survival rates, farmers used zeolite lime to neutralize rotting sediment and create a more favorable habitat. The steady release of nutrients from the lime promotes plankton growth, which in turn helps the cockles flourish. By carefully positioning lime-filled bags to dissolve slowly in the ponds, cockle farming conditions were greatly improved.

Blood cockles grown on farms typically achieve a marketable size of roughly 80 cockles per kilogram, which takes about a year and a half of growth. There are two major species that are commonly grown in Thailand.{{Cite web |title= |url=https://www4.fisheries.go.th/local/file_document/20190612162228_1_file.pdf |archive-url=http://web.archive.org/web/20211028133048/https://www4.fisheries.go.th/local/file_document/20190612162228_1_file.pdf |archive-date=2021-10-28 |access-date=2025-04-17 |website=www4.fisheries.go.th}}

The first is the Malaysian blood cockle (Anadara granosa), which was first imported for farming in Thailand. However, this species is also native to Thai seas. The second is Anadara nodifera, which thrives in Phetchaburi Province. {{Cite web |title= |url=https://www4.fisheries.go.th/local/file_document/20190612162228_1_file.pdf |archive-url=http://web.archive.org/web/20211028133048/https://www4.fisheries.go.th/local/file_document/20190612162228_1_file.pdf |archive-date=2021-10-28 |access-date=2025-03-17 |website=www4.fisheries.go.th}}{{Cite book |last=วิธีเลี้ยงหอยแครง |title=}}

1. Choose coastal areas where blood cockles grow naturally or where seed cockles are readily available.
2. The ideal location should have a smooth, gently sloping muddy shore with an incline of no more than 15°. It should be positioned in a sheltered bay to defend against strong waves and currents, preventing the cockles from becoming relocated and collecting in one spot.
3. The substrate should be composed of fine mud, silt, or clay mixed with mud. The surface sediment should be at least 40-50 cm thick to ensure a soft, uniform consistency. There should be no piles of decomposing mangrove leaves or organic detritus.
4. Water depth in the farming area should be between 0.5 and 1 meter (at mean sea level). Cockles should not be exposed to direct sunlight for extended periods of time, and low tide exposure should be limited to 2-3 hours at most.
5. The water's salinity should fluctuate between 10 and 30 parts per thousand. Prolonged exposure to freshwater conditions can result in a high mortality rate.
6. The agricultural location should be free of industrial pollution and home wastewater, as they can increase death rates, lower the quality of cockle meat, and endanger consumers' health.

Blood cockle farming in Thailand is divided into two systems: traditional farming and developed farming.

Traditional blood cockle farming in Thailand is primarily a small-scale, family-run industry spanning 5 to 30 rai per household. Farmers enclose their farming plots with bamboo fences to keep the cockles contained.

The size of the seed cockles employed varies by species. If the native strain from Phetchaburi Province is used, larger seed cockles of 400-1,200 individuals per kilogram are stocked, with 450 individuals per kilogram being the ideal size. Stocking densities typically range between 800 and 1,500 kilos per rai.

Because native blood cockles can travel through the sediment, constant monitoring and redistribution are required to avoid overpopulation and encourage uniform growth. Farmers often undertake density inspections every 15 days or once a month, using a rake-like equipment known locally as "phong" to equally distribute the cockles.

The Malaysian blood cockle strain (Anadara granosa), which is frequently derived from Satun Province of Malaysia, is loaded with smaller seed cockles weighing 1,000-3,000 individuals per kilogram, with 2,500 being the most common size. Unlike the native strain, Malaysian blood cockles do not move, though they may cluster together when first introduced to the farm. As a result, farmers employ boats fitted with rake gear to disperse and equally scatter the cockles over the property. This technique is only required at the start of the farming cycle.

Stocking densities for this system range from 300 to 3,000 kilos per rai, and the number of cockles naturally rises over time as they mature. Farmers utilize boats to harvest and size-sort the cockles, returning smaller ones to the farm for future development.

The harvesting season varies by species:

Malaysian strain: 1–1.5 years.

Native strain: 1.5–2 years.

At harvest, both strains average 80-120 individuals per kilogram, yielding 2,000 to 3,000 kilos per rai per cycle.

This traditional agricultural method is notably popular in Thailand's Inner Gulf, particularly in the provinces of Phetchaburi and Samut Songkhram.

The enhanced farming system is a large-scale commercial enterprise that spans 200-1,000 rai per farm. Enclosures, like traditional ways, are used to demarcate farmland borders.

In this system, small seed cockles are stocked, with the Malaysian blood cockle strain (Anadara granosa) being the most widely employed. The seed size ranges from 1,000 to 3,000 individuals per kilogram, with 2,500 being the optimal stocking size. The size selection and stocking density are comparable to those utilized in the traditional farming system.

Large-scale cockle growers frequently provide seed cockles to smaller-scale producers, with costs ranging according to seed size.

The cultivation phase lasts between one and two years, after which the cockles reach a marketable size of 80-120 individuals per kilogram, yielding around 4,000 to 5,000 kg per rai per cycle.

This farming style is frequently used in coastal areas along the Gulf of Thailand and the Andaman Sea.

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