We are in Ban Sai Ngurn shrimp Farm in Songkhla Lagoon, Thailand. Ms Kanokwan Loykulnant welcomes us despite the incredible heat — it is 2 in the afternoon.
Five years ago, the white spot disease killed all shrimps: 100% mortality; 0% survival. Now disease prevention is key. It all starts with keeping water quality and selecting the best shrimps.
We need to avoid mortalities, so we invested in water quality. We invested in RAS and implementing control measures.
The first control measure starts when they buy the 11 mm shrimp from a hatchery located 100 km away.
I was lucky to see the process and it goes like this:
The shrimps are transported from the hatchery to the farmers’ lab station. The shrimp come in water with aeration (17.6 mg/L of oxygen) at 27°C.
But before shrimps are sent to the ponds, they go through several tests:
1. Stress test — 100 shrimps are placed in freshwater (salinity=0 ppm) for 30 minutes, followed by 30 minutes in seawater at 30 ppm.
2. The white spot disease test, a kit is used to test for this
3. The hepatopancreas (liver) test of 15 shrimp is inspected under the microscope.
If the shrimp fail these tests — if more than 10% die in the stress test, or if more than 10% show liver problems, or if the white spot test is positive the farmer won’t buy them and the hatchery will need to provide a new batch of shrimps for inspection.
Today, the shrimp passed the test; they can now go to the nursery RAS. They will stay there for 30 days, 5.000 shrimp in each tank. The nursery is tidy and clean; it is empty now, waiting for the new batch of small shrimp. The water salinity needs to be constantly adjusted — Ca, Mg and Na, salt bags are pilled.
In 30 days’ time, these shrimps will be ready to go to the earth ponds.
But right now, some ponds are empty, a bulldozer rests in the bottom. I can see the opening in the middle, the incoming pipe, the outgoing pipe, some aerators.
The bottom can become very dirty— full of organic matter, so after every cycle, we remove the excess organic matter and let the pond dry in the sunshine. Nothing is wasted, this company also owns some coconut and banana plantations. Apparently, the salty organic matter is an excellent fertilizer — it makes coconuts sweeter.
We drive to the nearest pond with juvenile shrimps. Paddles rotate, water splashes — several rows of aerators are displaced to prevent oxygen dead spots — proper aeration is crucial. The milky turquoise colour of the pond contrasts with the greenish colour from the lagoon. I can’t see a single shrimp. The water is coloured with blue food dye to prevent algae blooms — it looks like a cartoon. In the past they tried other colours, blue turned out to be the best colour — it looks good too.
So the shrimp have been in this pond for 20 days now, how big are they? — I ask.
I don’t know — he replies — let’s see.
These shrimps have been hand fed with dry pellets, 5 times a day, during the daytime, and never at night. He shows me the table with the optimized amount of feed depending on the size of the shrimp and numbers in the pond. They keep a close eye on feeding behaviour — if the shrimp stop feeding they test for white spot disease. If they carry on eating well, after 30 days or so, they move to automatic feeding — 45g of dry pellets every 5 minutes is delivered for 10 hours. A mix of probiotics is also used throughout the entire grow out period.
We drive again to the next pond. These shrimps are big, they are 70 days, and in another 20 days or so they will be ready for sale. Small tilapia swim towards us — tilapia is added to the tanks or the canals to keep the ponds clean. They come from a local hatchery and are sold locally once they start growing.
In 20 days if the factory offers a good price, 10 men will fish 100.000 shrimp from this pond. They will use a net it will take them 30 to 60 minutes. Then 10 minutes driving to the factory.
Some shrimps will be exported alive to Malaysia and Singapore, transported in water at 15 degrees with oxygen. The frozen product is exported to the USA via Phuket airport, a 5-hour drive from here.
India is starting to grow shrimp too; they can become a competitor and if the production increases the prices will drop. So, for now, this company which has 11 other shrimp farms, has no interest in increasing its production. The key, he tells me is keeping the quality, following the standards and learning from other companies how to control for diseases.
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?