Standard measures of Artemia quality include hatching percentage, cyst count and hatching efficiency. These are well defined, and can be replicated with the proper equipment and procedures.
But one key determinant of quality - separation - is recognised as important but has not been subject to a well documented quantitative test.
Separation is a measure of how well the newly hatched Artemia (nauplii) detach and separate from their shells and any other debris within the batch.
It is important to the health of the shrimp larvae. If a larval shrimp eats shell fragments or other debris, the particle(s) might lodge in the digestive tract, block the passage, and cause death.
Many buyers and sellers measure the quality of separation subjectively by inspecting a sample and judging 'how it looks'.
Now, Eric Hol, chief engineer for Avocet Artemia, has developed the Baroes Separation Test (BST) to quantify Artemia separation on a universal scale. This begins with steps many aquaculturists use in their assessment of separation quality.
A hatching solution with Artemia nauplii is poured into a beaker and left to settle. As the test progresses, three layers form in the beaker: the empty shells float on top, the hatching medium clears in the middle, and the nauplii and debris fall to the bottom.
By looking up through the bottom of the beaker, one can assess the separation quality: nauplii are a translucent reddish-brown in colour, while debris (shells, sand, etc.) generally appear as black specks.
Good separation is demonstrated when few black specks appear.
The BST expands on this subjective method. For full details contact Avocet Artemia Inc, 2010 South 1000 East, Salt Lake City, UT 84105, USA, Fax: +1 801 463 9705, e-mail: Topper@brineshrimp.com.
(excerpts from article in Fish Farming International, December 1997, Vol. 24, No. 12)