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June 28, 2013

United States

Mississippi—Large-Scale Copepod Production System

 

Researchers at the Gulf Coast Research Laboratory (GCRL) in Ocean Springs, Mississippi, USA, have built a large-scale, biosecure, indoor production system for marine copepods that combines batch culture of adults with the continuous culture of eggs.  It produces pathogen-free nauplii and requires 50% less labor than smaller-scale systems.

 

The copepods (Acartia tonsa) produced at GCRL are used almost exclusively for the culture of the Gulf of Mexico red snapper, Lutjanus campechanus.  A. tonsa was chosen because it is a local species, and the size ranges of nauplii, copepodites and adults are appropriate for many marine fish that require copepods for first feeding.

 

Built in a climate-controlled building with ultraviolet-filtered air, the system is composed of four separate but identical subsystems: (1) 1,000-liter growout tanks, (2) 2,200-liter egg production tanks, (3) 150-liter egg-collection tanks and (4) 2,600-liter water-storage tanks.  Salt-mixing and water storage tanks are located outside the building.  Each subsystem has three circular 900-liter, cone-bottomed growout tanks linked together by a pipe that empties by gravity into a single 2,200-liter cone-bottomed egg production tank.  Water and eggs are withdrawn by gravity through a 200-μ screen on a 10-centimeter center standpipe that flows into a 50-μ plankton net suspended in a 200-liter egg collection tank.

 

Water returns from the bottom of the egg collection tank to the egg production tank via a four-centimeter airlift with a flow of 10-14 liters a minute.  Each tank receives a gentle supply of air through four-centimeter-square air stones.  This aeration helps to evenly distribute the algae and copepods.  A wooden platform surrounds the tanks to provide a working surface for the staff.

 

The first step in the production sequence is the stocking of the growout tanks with freshly harvested copepod eggs.  The tanks receive feed daily beginning with 0.5 liters (approximately 25,000 cells/mL) of Isochrysis galbana algae, increasing to 5 liters (approximately 200,000 cells/mL) of algae on day seven.

 

The second step occurs every five days when half the volume of one of the egg production tanks is drained, and the entire volume of a 14-day-old growout tank is added.  The egg production tanks receive 11 liters (200,000 cells/mL) of algae every day.

 

The third step is the harvest of the egg collection tanks each day, and all eggs are transferred to a beaker for counting.

 

A portion of the eggs is used to start another growout tank, and the remaining portion is hatched out to feed the young red snapper larvae.  The eggs are then incubated in circular 200-liter egg-hatching tanks.  After hatching, the nauplii are added to the snapper larval rearing tanks.  The average daily harvest of eggs ranges from 6 million to 16 million eggs, which, after hatching, produce from 4 to 6 million nauplii.

 

All tanks are filled with reverse-osmosis-filtered, artificial seawater.  The seawater is mixed with commercially available salt and tap water.  The temperature averages 25° C, and the salinity is maintained at 25 part per thousand.  All the nitrogenous waste products remain at low levels because they are consumed by the algae, and all system water is reused in fish production systems.

 

Information: To view the entire article, click on the link in the Source below.  On the page that opens, look for the “Magazine” tab under and to the left of the main tab bar.  Click on current issue.  On the page that opens, you will see the options to “View Online” and “Download”.  I have found that the downloaded version is easier to work with.  You will get the entire July/August issue of The Global Aquaculture Advocate.  Go to page 76 to view the article on the copepod culture systems, which includes two pictures and a diagram of the system.

 

Information: Brie Sarkisian (brie.sarkisian@usm.edu), Thad Cochran Marine Aquaculture Center, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564, USA.

 

Source: The Global Aquaculture Advocate (The Global Magazine for Farmed Seafood).  Editor, Darryl Jory (dejry2525@aol.com).  Large-Scale Production System for Copepods.  Brie Sarkisian  and Phillip Lee.  Volume 16, Issue 3, Page 76, July/August 2013.

 

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