Maximus applies a hatchery technology, which combines the application of copepod technology with an ecological balanced larvae rearing environment.
RAS technology is used in combination with addition of intensive cultured algae cultures to established a natural like but optimized water chemistry and biology in the larvae rearing tanks, to support the early development of the fish larvae.
Picture copepod distribution system, with first feeding tank in front.
The larvae are fed on copepods, but with some addition of rotifers and Artemia.
Artemia and rotifers can be suitable as an energy source for the fish larvae, but as approximately 40% of the food/energy consumed by the fish larvae turns into growth, then to obtain optimal growth performance and perfect fish larvae development, approximately 50% of the feed to Marine fish larvae should be copepods.
Figure show DHA levels of Copepods, Artemia and rotifers
Feeding the larvae on copepods, facilitates a faster growth rate.
The experience is further that the fish will continue to obtain a faster growth through out all the life stages, if they have started off their life being fed on copepods, improving the overall economy in the fish farm, from fry production to harvest.
Feeding the fish on copepods has the following benefits:
Uniform size of fish in bath (later less work effort on grading)
Deformities rarely seen
Improved immune system, and more resistance to diseases
Production setup for marine fish fry, turbot, kingfish and Tuna:
The fish fry are going through 3 phases at the hatchery, before being shipped to the grow out facility:
Egg incubation Hatching:
The egg incubation is the phase from spawning and up to the point where the hatched larvae, have mostly absorbed the yolksac, at which point the larvae are ready to start feeding. This production phase will for the species, that will be produced at Maximus, only last a few days. It is a relative simple phase, which requires little, but a very controlled water quality, with full temperature control, and high hygienic standards.
The First feeding phase:
The following phase, first feeding phase, is the very most complicated phase for production of marine fry, and for production of marine fish in general. The larvae are prior to first feeding transferred to first feeing tanks, of which there are 12 of at Maximus, with the production plan to start up 4 tanks at each run, each run separated with 7-10 days interval.
The water quality and composition inside the tank is very important. The correct bacterial balance is controlled by a special designed RAS system- Biofilter setup, and intensive algae cultured in a separate production are added to the tanks, creating a natural like, but very balanced and safe larvae culture media.
Then the correct amounts and types of live feed prey are added to the tanks, according to a feeding protocul which will be individual for each specie.
For a period of approx 3 week live feed prey is added to the tank. This is mainly different stages of copepods, but also some amounts of Artemia and rotifers, which are cultured in separate production systems inside the facility. During the first feeding phase, the larvae will go through the stage of metamorphosis, where the fish larvae will transform from a fish larvae, into a small fish fry which will actually look like a fish.
To facilitate the balance in the first feeding tanks, separate cultures of Copepods, Microalgae, Rotifers and Artemia are required.
First feeding tank at Maximus. The tank is started up with algae, and various stages of copepods, Artemia and Rotifers are added in an optimal mix, according to specie and larvae age.
The concept original developed at Maximus, has been adopted in several other marine hatcheries, on this picture Futuna blue in Spain.
The tank concept has proven useful for production of Kingfish, Bluefin tuna, Sole, halibut and Turbot.
This tank from Aquinor in Chile, equivalent to the two tanks above. Observe the double outlet screen, as in the other tanks, originally developed for Maximus.
The copepods are cultured in big tanks, as the reproduction is sensitive to densities, and the production is based on influx of sunlight. For a continuous production a set of 6 tanks are required. The tanks at Maximus are each of 2600 m3.
The Copepods develop in 12 stages, which makes it possible to use a single specie of copepods to feed the larvae from shortly after they hatch, at a size of only 3-4 millimeter in length, and up to a size of 60 mg wet weight when the larvae/fry now passed metamorphosis, can be fed on 0,5 millimeter dry pellets.
On the picture the copepod grading/distribution system, the tiny stages of the copepods are graded, in sizes to match the requirements of the larvae during the various stages of development.
Artemia are frequently used as the dominant feed source for fish larvae. The problem with this little creature of only a little more than half a millimeter in length is, that it does not match the natural requirements of fishlarvae, regarding fatty acids and amino acid. In reality it is a very unnatural feed organism for the fish larvae, as it has its habitat in some very saline inland lakes not connected to the sea.
Artemia hatching cones at Maximus. The Artemia are very easy to work with, which is the main reason, why it is applied in the industry. Using Artemia as the sole live feed source for the fish larvae, would have consequences on the quality of the fry produced.
Top view of Artemia hatching coni at Maximus. With water dosing system.
Rotifers is another substitute to Copepods covering the larvae until they are big enough to ingest Artemia, if copepods are not available in sufficient quantities or not used at all. The rotifers will be from 150 to 300 my in size depending on stock.
From a nutritional point of view they are quite a bit better for the larvae than Artemia, but they can not match the copepods by far.
Rotifer culture system, the picture is actually not from Maximus (From Aquinor) but the setup is almost equivalent, at present under renovation after many years in use.
Algae cultures are required to stock tanks, and to maintain the necessary algae levels in first feeding tanks.
Maximus has until 2013 applied an old faction algae bag culture concept as on the picture, from another hatchery, which works well. But after the renovation a slightly different concept will be implemented
The weaning/nursery phase:
Once the fry have reached a size of approx 50 mg, they can be transferred into the weaning phase, where the fry will be weaned to feeding on dry feed pellets..
The weaning of the fish can be either in a separate facility or it can take place into the same tanks as the first feeding, but then the water inlet and outlet should be connected to another water treatment system. That is an option, which will exist at Maximus once the upgrade of the facility has been completed in 2014.
On turbot it is better to do the weaning after transfer into weaning tanks, where as for kingfish and tuna, it might be more optimal to keep the fry in the first feeding tank, also during the weaning phase.
Weaning tanks for turbot. The fry will be transferred to these tanks when the fry are approx 50 mg . For Kingfish, bigger circular tanks will be used.
The water supply to the weaning nursery systems as well as first feeding, is from RAS systems. This RAS system on the picture at Maximus, was one of the first RAS concept developed for use with seawater. The concept was developed in 1996 by Bent Urup. This unit being one of the very first installed, based on a double loop concept with gravity CO2 stripper, a multi step biofilter with fluidized fixed biofilter media.
In spite of the age, this concept is still being applied in the industry.
For the new RAS systems though, within Sashimi Royal, a new concept with a more efficient CO2 stripper and a fully fluidized multistep filter which requires less maintenance, and which is less costly to build, will be chosen.
Turbot fry at Maximus of approx 60 mg, a few days after transfer from first feeding tanks to weaning tanks.
And the fry 7-8 weeks later, at a size of 3-5 gram, almost ready fro shipment to grow out facility.
Illustration of tissue composition of larvae of halibut after feeding on Artemia, rotifers and copepods.