The end of the instant shrimp farm
It used to be so easy — said Ms Kanokwan Loykulnanta — while the lab technician inspects the liver of a 10-mm shrimp under the microscope. You used to feed the shrimp for 3 months, harvest and sell. It sounds like instant noodle instructions. But now everything got complicated: you need to control the water quality, clean the tanks, check the shrimp…
Five years ago, all shrimps died — that is 100% mortality. The culprit? White spot disease. The cause? The usual suspects — climate change; water pollution; poor shrimp genetic diversity; maybe too many shrimps, maybe too many companies using the same water body. But we can’t be sure. We are in Songkhla Lagoon visiting Ban Sai Ngurn Shrimp Farm — they grow Litopenaeus vannamei.
I know sometimes all shrimps die on a farm. Everyone I meet blames climate change — farmers, academics and the fisheries department staff. As I see it, the cause is usually an imbalance to the system: environmental and socio-economic factors that all together are a bit too much.
Maybe the Lagoon has too many users: fishermen, farmers, tourists… Maybe the Lagoon has untreated sewage discards. Then there is the lagoon shape: its size in relation to the small opening in the South, the shallow water 1.5 to 3 meters…
But also, the seasonal patterns — the sunny hot days followed by heavy rain; the extra freshwater and sediments followed by algae blooms; isopods that parasite the sea bass and the white spot disease that kills the shrimps … this is all connected.
But the company can’t fix the system so they adapt. They move away from the natural water body and its whims and re-create their own system, one that they can have more control over — a recirculating aquatic system (RAS). I see a RAS system as an intensive care unit — a support life system for an aquatic species. The degree of control and technology varies.
So, it comes with no surprise that the first thing they show me on the farm is a detailed diagram of the RAS system. The company is 20 years — it is well established. When they had 100% mortality they invested in the water quality and control measures to prevent diseases. They invested in quality.
You are reading a short series of factual stories about aquaculture and fisheries in Thailand — this is the second of five stories. I use storytelling to facilitate conversations about aquaculture, fisheries, and all the other industries along the way. If you are an educator you can use this site in blended learning — see below learning objectives, suggested activities and further reading.
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Topics for discussion and further investigation:
- What is a RAS system and how does it work (make a diagram and identify all its key components)?
- Find more info about the white spot disease, what is it, how is it transmitted?
- How can you prevent the white spot disease.