By Craig Browdy, Peter Van Wyk, Chris Stock, M.S. Diego Flores and Murthy Chennamsetti

Part 2: Commercial results of using synthetic Artemia in hatcheries and ponds

Global aquaculture growth will require additional Artemia supplies, with no obvious additional production sources in sight. The alternative is formulated, synthetic products that provide the same nutrients as live Artemia and can also offer a more consistent enhanced nutrient profile, stable quality and supply, biosecurity and also act as a delivery mechanism for immunostimulants, enzymes and other beneficial compounds.

In part one of this article, we discussed the relevance of Artemia to the growing aquaculture industry around the world, the global status of Artemia resources and the potential bottleneck its limited supplies could represent. The possibility and advantages of replacing Artemia with innovative manufactured synthetic products was presented. Here in part two, we discuss results of some of the field trials at the hatchery and pond stages in commercial facilities as well as some perspectives on the future of Artemia replacement.

Performance of synthetic Artemia

Our synthetic Artemia has over a decade of proven commercial application in hatcheries and nurseries in several countries all over the world.

Commercial hatchery tests – Western Hemisphere

In an earlier test, we compared two feeding protocols using 100% synthetic Artemia (not from hatched cysts), and evaluated the dietary impact of the two protocols on growth and survival of larval shrimp using commercial mass production systems. Two feeding protocols (treatments) for Litopenaeus vannamei were tested in two types of rectangular 20 m3 fiberglass tanks taking into consideration the main types of tanks commonly used in shrimp larviculture. In one, flat bottom Asian style tanks were used, coupled with the use of easily suspended liquid larval feeds and synthetic Artemia. In the other, parabolic American style tanks were used, together with low-cost, dry diets and synthetic Artemia. Each treatment had three replicates.

Tanks were stocked with nauplii (N) at 160/L, and the test ran for 21 days, from stages N5 to PL15 (post larvae 15). From N5 to PL4, the microalgae Thalassiosira pseudonana were added and maintained at a density of 60,000 - 100,000 cell/mL. Water temperature was maintained at 30.8 - 31.8 °C and dissolved oxygen at 4.5 - 5.0 mg/L; pH was stable at 8.2 for the duration of the test.

Table 1 shows the results in growth and survival of N3 to PL15 in each treatment. The experimental results indicate that regardless of the format of the supporting diets (liquid versus dry) and the type of production tanks (flat versus parabolic), excellent results were achieved in the commercial hatchery trials using no Artemia in the feeding protocols.

This test was carried out at a hatchery that had eliminated hatched Artemia use and had already adopted a protocol that exclusively used synthetic Artemia. The facility noted increased survival, sustained improvements in water quality and increased hatchery productivity, leading to decreased production costs and higher profitability.

Subsequently, between 2014 and 2016, we carried out several additional tests at various commercial hatcheries in five countries in Latin America, where we evaluated our artificial Artemia at 100% replacement levels versus controls fed standard diets. Table 2 summarizes test conditions and results; % survival and animal weight at PL4 were comparable or better than those of controls, demonstrating that 100% replacement was possible depending on the hatchery setup and equipment, operators and other conditions.

At these innovative hatcheries in Latin America, management protocols have been developed which enabled the complete replacement of Artemia. Benefits reported include reduced Vibrio counts and improved biosecurity which enhanced production efficiencies and consistency. The trials were conducted with synthetic Artemia at stocking densities ranging from 85 to 300 nauplii/L). Successful results have been achieved in several countries, using different management and feeding protocols; survivals from 50 to 92% in the best cases were obtained.

Table 2 also shows that the growth of the shrimp and larval development rates were similar to those obtained in normal cultures fed with Artemia ranging from 0.7 mg in 10 days for PL4, up to 5.5 mg for PL13 in 20 days of culture.

Doing away with traditional protocols

One of the strategies employed by the most successful hatcheries with Artemia replacement involves the splitting of daily rations into larger numbers of feedings. The traditional feeding of live Artemia 2, 4 or 6 times/day has been replaced by innovative managers who feed dry and liquid manufactured feeds of all kinds up to 12 times/day, providing the developing larvae with access to fresh feeds on a frequent, semi-continuous basis.

The results achieved by innovative hatchery managers who have adopted Artemia replacement is being shared among producers. More and more hatcheries are gaining confidence in the safe, simple use of liquid synthetic Artemia by gradually increasing the replacement rates over time.

An additional application for synthetic Artemia beyond its use in the first and second phase of the larval culture system is its growing commercial use in Latin America for the transport of post larvae from hatcheries to nursery systems or grow-out ponds. Synthetic Artemia is easily maintained at the farm to reduce cannibalism during acclimation prior to stocking in the culture ponds. In plastic bags, tanks or tubs, water quality is one of the primary concerns of producers, especially in long transport. The stability of synthetic Artemia offers an effective and economical option for reducing handling stress and cannibalism while maintaining needed water quality.

Commercial hatchery tests – India

Over the past 12 months, a series of Artemia replacement trials were run at six commercial shrimp hatcheries in Andhra Pradesh, India. Each hatchery dedicated three tanks to testing replacement by reducing by 50% the amount of Artemia fed and substituting with synthetic Artemia. These three tanks were compared with three control tanks. To minimize the influence of genetic variation the trial and control tanks were stocked concurrently, two at time from the same batches of nauplii. As shown in Figure 1, the survival rates varied between hatcheries but were generally typical for Indian hatcheries, varying according to the season when the tests were run. Standard deviation bars in the graph indicated that Artemia was successfully replaced with no significant changes in survival rates. At the hatchery with the best culture conditions, as indicated by high survivals achieved during the cooler season, performance results for tanks where Artemia was replaced equalled or exceeded the results achieved for the Artemia fed tanks in survival, growth and post larvae quality measures (Table 3).

Blue Star Marine Hatchery

With the kind collaboration of a customer, Blue Star Marine Hatchery in Ramatheertham, Nellore, India and the efficient support of Dr Ravikumar, we recently conducted a controlled trial to prove that our synthetic Artemia could replace hatched Artemia and improve post larvae quality and survival. The control treatment included several commercial, shrimp larval feeds and a commercial probiotic. The experimental treatments included the same commercial feeds and probiotic as in the control group, plus our synthetic Artemia product.

The 10-tonne larviculture tanks used in the trial were rectangular with flat bottoms, filled with dechlorinated water treated with EDTA. Each tank was stocked with two million nauplii (N5) produced from the hatchery’s broodstock (from a commercial US supplier). Tanks had grid aeration, and water was exchanged at 40% daily from PL 6 until harvest. A commercial probiotic was added at 20 g daily, and also sugar at 250 g starting at the mysis (M3) stage. EDTA was also added and NH4-N, alkalinity and pH were monitored, and the larval shrimp were fed six times/day.

Post larvae fed with our synthetic Artemia scored 100% survival in stress tests, and microscopic observations of the animals showed high numbers of fat globules and muscle: gut ratios of 4:1.

Our conclusion for this trial at Blue Star Marine Hatchery is that Artemia replacement with our synthetic Artemia liquid diet demonstrated similar performance when compared with hatched Artemia and was cost-effective.

Use of synthetic Artemia as part of a prevention protocol in hatcheries

Many shrimp hatcheries experience unusual mortalities during larviculture, likely due to bacterial and other pathogens. These mortalities typically involve an increase in the concentrations of Vibrio sp. (V. parahaemolyticus, V. vulnificus, V. alginolyticus), in the culture tank environment which affects various shrimp larval stages. Recently, virulent strains have emerged causing gross symptoms which include a reduction in appetite, progressive atrophy of the hepatopancreas and a reduction in overall activity. A small percentage (2-4%) of the population in a tank is initially affected, with exponential contagion of the rest and total mortalities in 12-14 hrs. Synthetic Artemia can be an important component in a prevention protocol, as shown in Table 4 that presents data on bacterial counts for a commercial hatchery in the Western Hemisphere which used Artemia nauplii versus synthetic Artemia. Some of the practical measures undertaken that have reportedly helped, according to one major hatchery in the Western Hemisphere, include:

• Bacteriological control: reduction of Vibrio sp loads in the environment and larvae; determine loads in algae and reservoir water; and evaluate efficiency of all treatments, including probiotics use, chlorination and addition of organic acids.

• Establishment of microbial health indices: identification of the levels, areas and foci of bacterial contamination in hatchery systems through periodic ongoing bacterial analyses and evaluations of animal behaviour.

• Intensive control of algae quality: externally procured certified microalgae, and use it during its optimum growth phase.

• Control of larvae quality: rate of development of larval stages, growth rate, water quality management, stress tests, size variation and bacterial load evaluations.

• Replacement of Artemia nauplii with synthetic Artemia: a very useful tool in larval production, beneficial for reducing bacterial loads in the system without affecting larval quality during the larviculture phase.

Commercial pond testing

To address the question of whether post larvae produced with synthetic Artemia have the same quality as those produced with live Artemia, tests were conducted comparing pond results at a Latin American shrimp farm using post larvae produced with hatched Artemia cysts and with synthetic Artemia. Two hatcheries produced 6 million post larvae for the test: 3 million post larvae with a larviculture protocol using synthetic Artemia and 3 million post larvae following the larviculture protocol using Artemia hatched from cysts. The post larvae were kept in nursery tanks for 7-12 days prior to stocking into the grow-out ponds. A total of 72 ha of ponds were stocked at a large commercial shrimp farm with animals from the nursery tanks: seven ponds (36 ha) of the area were stocked with the post larvae produced with synthetic Artemia and six ponds (36 ha) with the post larvae produced with live Artemia from cysts. Figure 2 shows the results of the test in commercial ponds, showing equal pond performance from post larvae produced using artificial Artemia versus post larvae fed hatched Artemia.

Perspectives

When considering the projected growth of global aquaculture production to feed a growing human population, the continued increase in global demand for Artemia cysts could make its supply, availability and price a potential bottleneck for the growth of the aquaculture industry. These supply pressures become particularly acute when environmental conditions deteriorate in water bodies like the Great Salt Lake which currently provide the highest quality cysts.

A global industry as important as shrimp farming cannot completely depend on Artemia as an indispensable natural resource. Artemia, has historically demonstrated ups/downs in availability and prices. The expected growth of the aquaculture industry will demand more and more Artemia – where is it going to come from? One alternative is to culture Artemia on land, but to date large-scale culture efforts have not succeeded.

In the evolution of the aquaculture industry, the development of advanced hatchery diets designed to reduce dependency on live feeds remains an ongoing process. Many hatcheries have successfully decreased their overall reliance on Artemia, but very often Artemia remains a key component of most larval feeding regimes. Nevertheless, some pioneering shrimp innovative hatcheries have completely eliminated Artemia from their feeding protocols while improving overall results.

Artemia has undoubtedly played a valuable role in advancing the global hatchery business and the aquaculture industry. Yet it is critical that the industry comes to terms with the limitations of Artemia and continue to work with academic and industry partners to implement gradual replacement, thereby reducing the risks and costs of excessive reliance on this resource. As the supply of Artemia cysts is a potential bottleneck to aquaculture industry growth, developing practical and cost-effective alternatives to Artemia will surely help aquaculture be a more significant and sustainable provider of food for our growing human population.

Complete replacement of Artemia is possible, thanks to the availability of a complete, artificial Artemia replacement that has a consistent nutritional profile. Synthetic Artemia is pathogen-free and has no biosecurity issues. The product has constant availability and quality, with no storage or hatch-out concerns. Synthetic Artemia can be used for delivery of higher levels of nutrients, immunostimulants, enzymes and probiotics to enhance digestion and improve water quality and animal health.

Shrimp larvae do not need Artemia as they exist in their natural habitats which are devoid of Artemia. The key is to effectively provide the nutrients in live Artemia in the synthetic replacement. Years ago, many shrimp producers assessed the quality of aqua feeds solely on the fish meal and crude protein content percentage in the feeds. Today shrimp feeds are utilizing nutritional strategies aimed at meeting amino acid, fatty acid, micronutrient and other specific nutrient requirements. The reality is that cultured animals need specific nutrients in their feeds, and the same strategy can and is being applied during the larval phase of penaeid culture with the use of synthetic Artemia.

Can all hatcheries replace 100% of the Artemia cysts they use? No, it depends on the particular hatchery, its infrastructure, resources and technical personnel capabilities. An initial goal of 50% replacement level could certainly be achieved by most shrimp hatcheries, and increasingly higher levels of replacement can be achieved with experience and training. Artificial Artemia is another important tool for hatchery producers to reduce their dependence on a limited resource.

References

Craig Browdy is Director of Research & Development

Peter Van Wyk is R&D Technical Manager

Chris Stock is Sales Manager - Eastern Hemisphere.

Diego Flores is Technical Representative – Hatchery Feeds – Western Hemisphere

Murthy Chennamsetti is Technical Representative – Hatchery & Nursery Feeds.

All authors are with Zeigler Bros., Inc. USA.

 

AQUA Culture Asia Pacific Magazine - May/June 2017