mechanical stress for SHRIMP LARVAE

From: Paul Hale paul@paulhale.fsnet.co.uk
To: shrimp@yahoogroups.com 
Sent: 09 January 2003

QUESTION:

Would you describe vannamei larvae as hardy, like Artemia?  The Lysmata larvae appear to be delicate, maybe I am being too cautious.

Paul Hale
Curator Underwater World
e-mail: paul@paulhale.fsnet.co.uk

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COMMENTS 1 :

In larval culture of Litopenaeus vannamei and in hatching of Artemia cysts, both at commercial densities, the use of airstones is standard procedure. Culture water agitation is quite strong and no harm seems to result.

Julio Estrada
e-mail : julioe@speed.net.ec

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COMMENTS 2:

I have observed many trials with ornamental shrimp larvae and
personally played around with L. debelius, L. ambionensis and Stenopus hispidus. The larvae do appear to be very fragile with their long paddles, but they are not as bad as some other ornamental crustacean larvae.
We have used both aeration and water flow at different times to keep
the larvae and feed in the water column, but the most important
point to look at is the design and shape of the tank to enable
everything to circulate with a minimum input.
 
Peter Bridson
e-mail: peter.bridson@ekno.com

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COMMENTS 3 :

I would welcome any observations you may have on rearing these shrimps such as system design, nutrition and disease. There is lots of conflicting information out there, you can't beat personal experience.

I am currently using a small kryslier design, which is powered by an external airlift drawing water from the main tank and into the open top of the kryslier (which is in the tank).  This creates the circular flow and also exchanges the water, there does not appear to be any dead spots but some of the larvae do accumulate in one spot which I think is due to an external light source rather than water flow.  You mentioned that you need to have the minimum of input to maintain circulation, would you say that high flow rates are detrimental to the larvae.  Considering that we are using the circulation method as a way of exchanging the culture water I would be conscious of reducing the water flow rate too low.

Paul Hale
e-mail : paul@paulhale.fsnet.co.uk

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COMMENT 4:

I really couldn't compare directly, as I haven't followed Artemia past the naupliar stage when they become vannamei / fish snacks. And about Lysmata larvae I know zip. I could only say vannamei larval-rearing people worry far more about water quality and pathogen exclusion than about mechanical stress, but your babies might be a different story. What's their natural habitat like?
At any rate, Peter's advise seems eminently sensible if you have a small number of animals to risk and the larval stage is that long.

Julio Estrada
e-mail: julioe@speed.net.ec

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COMMENTS 5:

For exchanging water in P. vannamei larvae culture, you can also lower the level of your tank to the amount needed: if you need to exchange 30% per day, you lower your tank by 30% and add new water back to 100%. This has two major advantages: You can really control the % of exchange, you can feed your rotifers or Artemia based on a 100% volume but applied on a 70% so that by the time your tank goes back to 100% of the volume you´ve given your larvae a greater opportunity to catch a prey. The same method is usually applied with antibiotics (hope you won´t need it!).

Francois Brenta
fbrenta@hotmail.com  

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