INTERVIEW TRANSCRIPT - Bunjonk Nissapavanich

How do you clean your bottom soil?

We pump air and water to the bottom soil and this aerates the sediment. By this technique, the water turns turbid and we can control the pH of the water.

You have to do this everyday, right?

Yes, we have to do it everyday. The bottom soil will be clean and shrimp will be healthy.

Does it cause danger to the shrimp?

No, the shrimp can swim away. The shrimp pond uses a biological process for controlling the water. This is the way we treat the bottom sediment. Usually, there is a lot of organic matter accumulated in the shrimp pond. This sediment is composed of organic matter, hydrogen sulfide, which causes the problem to the shrimp. Shrimp like to lie down on bottom sediment during periods of temperature changes. If the sediment is not clean, shrimp will stress and become fragile to the disease. That’s why we have to treat the sediment.

After we pump the air and water to mix with the sediment, hydrogen sulfide will turn to sulfuric acid which then reacts with calcium to become gypsum. Gypsum is neutral and helps to buffer the water and control the pH of the water. By this method, shrimp will stay healthy because the toxic gases are neutralized. The suspension of sediment decreases the photosynthesis process and pH will not get too high in the afternoon. If photosynthesis is too strong, afternoon pH will be high and shrimp will stress.

After you use this technique, do you have problems with disease?

No, we have no disease problem. The growth rate is normal and survival rate is 80%.

What do you think about the natural water? Is it still suitable for shrimp culture?

During the years 1957-1967, shrimp culture was still an extensive culture that relied on natural water. There was no organic matter. The water was good; there was no sewage or any industrial pollution. Then in 1987, the shrimp culture system changed to intensive culture. There was more organic matter, more chemicals used, and more sewage and industrial pollution. That is why we had to change from an open system to a closed system. With high density in a closed system and a lack of appropriated water treatment, it finally caused failure in shrimp culture. It was the high organic matter and the pollution from community and industries.

Your system is natural, right?

Yes, it is a natural treated system. They already had one in nature, but when we put too much organic matter in it, it caused imbalance in nature. Some organisms disappeared. That is the reason why we have to rebalance nature again.

Why don’t shrimp farmers in the southern part of Thailand, who have disease problems, use this system?

The reason why people do not use this system is because they want to use 100 % of their area for shrimp production. If they have to change to the natural system, they think it will increase their operation costs and complicate and decrease their profit. But it is not true.

What is the density you use here compared with the others?

I use 30 pieces per square meter; generally, people use 60 to 100 pieces per square meter. They just think that if they raise 30 pieces per square meter, they will gain 1 ton per rai, so if they double the density they think they will double production. But they forget that shrimp culture and mathematics is very different.

Could you tell us about your name and where we are now?

I am at the Bunjonk Farm, the address is 59 Moo3, Tumbol Bang Chorn, Amphur Ban Poh, Cha Choung Sao province.

What is your opinion about the future of shrimp culture? Do you think people will turn to use the natural system?

Shrimp farmers both in Thailand and other countries encounter disease problems. Some can’t raise shrimp anymore, while the natural system has no problem. I think in the future all the shrimp farmers will turn to use this system.

If there are foreign markets for those who raise high quality shrimp, do you think it will help promote this system or not?

If there are markets that require shrimp culture from natural systems that avoid using chemicals or anything that’s toxic to the consumers, the demand from the market will push farmers to change to this system faster.

Why does low density culture have better chance to survive?

When we raise shrimp at 30 pieces/m2 compared with those who raise 60 pieces/m2, the lower densities cause less waste, are easier to manage, and the shrimp are more likely to be healthy and grow well.

How does low density culture affect the price of shrimp production?

Every pond is limited in its capacity, if you put many shrimp into the pond you get the same production but with a smaller size of shrimp production compared with when you put lower density in which creates bigger shrimp. Bigger shrimp get a better price that affects a lot of your cost and benefits the crop.

What do you think about your system compared to the others?

I think every system has the same target: to produce quality shrimp. But the ways to approach the target may be different. It is difficult to say which one is better, but the lower cost should be the good index. The one that produces with the lowest cost will be the one who survives.