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July 29, 2014

 

Can You Grow Bivalves in Shrimp Ponds?

 

Jimmy Maneckshaw (j.n.maneckshaw@gmail.com): Is it possible to culture bivalves (oysters, clams and muscles) in shrimp ponds?  Would their filter feeding help reduce the BOD (biological oxygen demand) and COD (chemical oxygen demand)?

 

Dallas Weaver (deweaver@me.com): The vast majority of bivalves require water supersaturated with CaCO3 (calcium carbonate) for proper shell growth.  Unless your shrimp ponds are in deep ponds that minimize pH variations caused by photosynthesis and maintain proper alkalinity and Ca (calcium) concentrations, the answer is probably no.

 

What often happens to the water in a pond when the nutrients increase, you get an algae bloom that uses up the CO2 (carbon dioxide) during the day and the pH increases to above 9, or so.  At that point CaCO3 and Mg (OH)2 (magnesium hydroxide) in seawater come out of solution and become part of the bottom mud and the supersaturated CaCO3 that normally exists in clean open ocean seawater disappears.  At night the CO2 increases and the precipitated CaCO3 wants to go back into solution, but it’s in the mud, so the shells of your bivalves may dissolve.  At night the pH is low enough and CO2 high enough to dissolve shell.

 

Ajitsinha (panchamaqua@vsnl.com): Do shrimps feed on bivalves?

 

Gruenberg Daniel (seagardenfoods@mac.com): As Dallas says, you may reduce plankton by adding bivalves, but you would be adding significant complexity to your system.  A couple years ago, an experiment by Thailand’s Department of Fisheries attempted this and the conclusion was that the system was too difficult to manage.

 

Hank Bauman (hank_bauman55@yahoo.com): Regarding Dallas's comments about the bivalves not doing well on the pond bottom, would it be feasible to glue the spat onto bamboo or another type of pole and place them vertically around the pond so the bivalves would not be sitting in the mud?

 

I was actually under the impression that oysters (Crassostrea gigas and C. virginicus) liked mud.  When I worked for Aquatic Farms in Hawaii back in the 1970s, we had a pond that we used to culture diatoms (Chaetoceros) for feeding the oysters in a raceway.  After some time—a year or so—the biggest oysters in the whole system were in the mud on the bottom of that pond.

 

Later Aquatic Farms tried recirculating water from a shrimp pond through an oyster raceway, and as I remember, it got pretty good oyster growth.

 

Carlos Macías Mendoza (carlosagustinmacias@yahoo.com): Jimmy, I estimate that you could grow three to four tons of mussels per hectare in shrimp ponds.  We use calcium carbonate.   Usually we only use lime (200 to 300 kilos per hectare every two days) when the alkalinity drops below 80, but alkalinity fell to 50 once and our shrimp began to die.

 

Judi Ramses Nieves (jrinieves@yahoo.com): Carlos, are the mussels imbedded in the substrate or attached to the pond walls or other structures? They could be used as fresh feed for the prawns if collected, crushed and thrown back in the pond.  The problem becomes the solution.

 

Sources: 1. The Shrimp List (a mailing list for shrimp farmers).  Subject: Bivalves in Shrimp Polyculture.  July 22–25, 2014. 2. Bob Rosenberry, Shrimp News International, July 29, 2014.

 

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