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ผู้เขียน หัวข้อ: India; Monodon and Low Salinity  (อ่าน 2253 ครั้ง)
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« เมื่อ: ธันวาคม 18, 2006, 09:22:29 PM »



This exchange took place on the Shrimp List in early December 2006:

Laurence (ecotao@yahoo.com): What's the lowest practical salinity level for growing Penaeus monodon intensively (6 to 8 tons per hectare per crop)? Is anybody doing it below 10 parts per thousand salinity, below 5 ppt or below 2 ppt?

Statish (skbodapati@yahoo.com): It is possible to grow P. monodon at almost zero salinity. Here in India low-salinity shrimp farming (less that 5 ppt) has been practiced for at least 10 years. But average production per hectare is around 3 to 4 tons. Hatcheries on the east coast acclimatize postlarvae (PL-13 and larger) to zero salinity before shipment. There's no problem growing monodon in freshwater, but a couple of years back Japanese importers said that they had a muddy smell. That problem has been rectified with better culture practices. In our observations, we found that the success ratio in low saline waters is phenomenal when compared with brackish waters.

Laurence (ecotao@yahoo.com): Thanks for the information. What sort of survivals are achieved at 3-4 tons and 5-8 tons?

Statish (skbodapati@yahoo.com): Survival is based on many factors, not just salinity. With direct stocking (introducing PL-15s to PL-18s directly to the growout pond without a nursery or acclimation phase), the average survival is around 50% to 70%. But if they are transferred from nursery ponds to growout ponds, then the survivals are around 70% to 90%. There are some instances when the farmers got 90% above survivals in 5-8 ton production, but their profit margins dropped because of pond management costs, like aeration and probiotics.

Ramjai (padlab@yahoo.com): Low-salinity shrimp farming of P. monodon got started in Bhimavaram, India, over two decades ago, long before low-salinity, P. vannamei farming developed elsewhere in the world. The farmers in Bhimavaram work with very low salinities (0.5 to 2.0 ppt) that have the right mineral content (ionic balance) for shrimp.

That muddy flavor in shrimp farmed at very low salinities is due to blue-green algae, an offshoot of the eutrophication of these waters caused by excess nutrient loading, possibly from old carp ponds. Unless this issue is addressed, it's going to be difficult to produce good quality fish or shrimp from these ponds.

Source: The Shrimp List (a mailing list for shrimp farmers, "shrimp-subscribe@yahoogroups.com"). Subject: [shrimp] P monodon growout salinity. December 4-7, 2006.

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