Hatch & Collect

Artemia are predominantly collected from the wild during their cyst stage. The embryos in the cyst develop up to gastrula stage, a point where they reach 4,000 cells whose development has been arrested by greatly reducing the metabolism of the embryo to almost a level which is close to zero (biologists call this ‘diapause’). This is the stage at which they can be harvested, processed, conditioned and stored as dormant or quiescent live organisms, ready to be used as feed in fish and shellfish hatcheries. These dormant encysted embryos are capable of severe dehydration.

Hatching

When outside conditions improve to the point where it is safe for the brine shrimp larvae to come out of their shell, the embryos will respond to a number of triggers and resume their metabolism. They will take up water, start to metabolize and convert their carbohydrate reserves, eventually increasing the osmotic pressure inside the cyst up to the point that the cyst shell bursts and the nauplius still enclosed in the hatching membrane (also called umbrella stage) is released from the cyst shell. Within the hatching membrane one can see the nauplius moving its appendages.

Within the next hours the hatching enzyme is secreted in the head region of the nauplius and the free-swimming instar I nauplius is released. Several elements play a crucial role in this delicate process, that aquaculture professionals need to imitate to optimally hatch Artemia cysts.

The presence of unhatched Artemia cysts and shells in the live feed entails several risks:

Risks at hatcheries

Increased biosecurity risk due to transfer of organic matter and high bacterial load
Maintenance problems (can foul the tank)
Complex chemical and non-sustainable way to decapsulate cysts

Risks with Nauplii

Tedious and cumbersome separation of nauplii and cyst shells after hatching
Separation techniques to remove shells, reduce viability and survival of the nauplii

Risks in fish and shrimp larvae

Possible infections
Gut obstruction with unhatched cysts and empty shells leading to mortality
Failed ingestion of cysts and shells by fish

Selecting the right Artemia products and hatching technologies is crucial to minimize risks and improve efficiency.

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Collecting

Traditional methods to collect Artemia

Double-sieving: the double trouble method

Traditionally, Artemia nauplii are often separated from the cysts and shells using a double sieve, through which nauplii can pass while cysts are caught on the upper sieve. Double sieving is labor intense and highly inefficient: cysts often remain in the final suspension and nauplii are physically damaged when pushed through the mesh. To overcome these issues a new technique was developed.

Decapsulation: an improvement with a catch

Chemical decapsulation was introduced to solve the shortcomings of double-sieving and facilitate the hatching of large volumes of Artemia. Decapsulation uses hypochlorite to dissolve the chorion and free the embryos. The method is complex, expensive and dangerous to Artemia and workers, who are exposed to hazardous chemicals and the toxic fumes produced during the reaction. Besides, the heat-releasing reaction virtually ‘cooks’ the nauplii, if not timed correctly.

SEP-Art Technology

The drawbacks from double-sieving and decapsulation make them inefficient and non-sustainable methods for the live Artemia nauplii production. It is important to simplify harvesting processes and develop an efficient and sustainable production of live Artemia nauplii.

The patented SEP-Art technology is a ground-breaking method to separate Artemia nauplii from their cysts using magnets.

Producing high quality nauplii
Maintaining the vitality of the Artemia nauplii
Reducing losses
Speeding up the process of handling and harvesting
Ensuring safety for workers
Limiting environmental impact