Questions About Biofloc Shrimp Farming
April 16, 2010
David Strnad (email@example.com): I have been studying indoor shrimp farming for a while and have successfully harvested a small batch of shrimp. I’m still learning and have no formal training in marine biology. I have a couple of questions about biofloc systems:
1. It appears that more fish can be raised in a gallon of water than shrimp. I was under the impression that this was because shrimp needed a lot of surface area. Now, I am reading that dissolved oxygen (DO) is the limiting factor to increased shrimp densities. Which position is correct?
2. Most of my experience has been with zero-exchange, biofloc systems. Is it possible to mature and breed Pacific white shrimp (Penaeus vannamei) in biofloc systems? Can you grow larvae and PLs in biofloc systems?
Eric De Muylder (firstname.lastname@example.org): Hello Dave, The problem of intensive shrimp farming is indeed density (10kg/m³, maybe a little more, is the maximum), which is far below finfish (up to 200 kg/m³). The problem is not DO, which could be supplied through pure oxygen if necessary. I believe the main problem is molting. In intensive systems, shrimp don’t have a place to hide after they molt. Their shells are soft. They can’t move or defend themselves. Beginning with their legs, their tank mates quickly cannibalize them. Adding substrates and hiding places helps alleviate the problem.
The other problem at high densities is blackspot, spots on the shell that don’t affect the health of the shrimp, but do lower the price you can get for them. For maintaining broodstock at breeding centers, bioflocs are a plus because they provide fresh nutrients for the shrimp. I wouldn’t use bioflocs to culture larvae because up to 0.4 grams, postlarvae are not able to cope with bioflocs and prefer microalgae. After that, they start benefiting from the presence of bioflocs.
By the way, I have developed a small turnkey system for intensive shrimp farming, called CreveTope.
Gintas Stasys Zavadzkas Leon (email@example.com): Dave, As Eric pointed out, you can inject oxygen, but because equipment and energy costs are high, oxygen is mostly used at breeding centers and hatcheries. Try to find a cheaper solution, like regenerative blowers.
With regard to culturing larvae in a biofloc system, I think it’s a good idea because it requires less feed and labor, especially if there’s some algae in your water. The management of these systems is complex and results can be mixed, depending on the your degree of expertise. You need a specific probiotic for your system, and the design of your hatchery must accommodate bacterial management, not just larvae, algae and water management.
Jeff Peterson (firstname.lastname@example.org): You should also check out the work done by the Waddell Mariculture Research Center in Bluffton, South Carolina. Contact Al Stokes. Please contact me [Jeff] offline if you need more information.
David Strnad (email@example.com): Thanks everyone, for your helpful input. I have talked to Russ Allen, he is a wealth of knowledge and very helpful! In fact that is where my shrimp came from. I still have a few perking along after a year. They have kind of hit a roadblock mostly due to my lack of ambition over the winter. So now I’m getting some new water started to see if I can take them further.
Sources: 1. The Shrimp List (a mailing list for shrimp farmers). Shrimp System Capacity. February 28 to March 22–23, 2010. 2. Summarized by Bob Rosenberry, Shrimp News International, April 5, 2010.