Print This Page


January 21, 2016

The World

The PL-Quality Discussion on The Shrimp List Continues

 

Anil Ghanekar (www.ecosecuresystems.com): We have observed that most cases of postlarvae size variation starts after PL-9.  When batches with size variation are reared in nurseries there is cannibalism.  The larger PLs eat the smaller ones, resulting in extremely low nursery survivals.

 

Here are some solutions to that problem:

 

1. Don’t use batches with a size variation of more than 10%.

2. Batches with high size variation may have better survival with direct stocking in well-prepared growout ponds.

3. Buy PL-9s or smaller and rear them in a biofloc nursery at high densities (5 to 10 PLs per liter) for two to three weeks; you will get even-sized, stunted juveniles between (100 to 200 mg) that will how compensatory growth in growout ponds with much better survivals.

 

Eric De Muylder (crevetec@gmail.com): Unfortunately, in the European Union, we don’t really have a choice, since somebody decided that we can only import from the United States.  I have repeatedly asked SIS to supply PLs with less size variation, and they confirmed they would, but then they send another batch with the same size variation, or less variation, but much smaller PLs.

 

For your info, when PLs arrive, I put them in a nursery and initially feed them algae and Artemia, and then use bioflocs after a couple of days.  Stocking is between 6.5 and 23 PLs per liter.  I give them Artemia twice per day for five days (last batches, 10 days) and dry feeds continuously, so there is plenty of feed available for all the PLs.

 

Of course, it is possible that cannibalism is high, but it is difficult to know if they eat live (probably molting) small PLs, or if the PLs die and are eaten afterwards.  I don’t observe any mortalities!

 

You can tune into the entire discussion at The Shrimp List (below).

 

Source: The Shrimp List (a mailing list for shrimp farmers).  Subject: Quality of PL11 and Subsequent Growth.  January 20, 2016.

Print This Page