58 Show Review Daniel Arana, BernAqua provided powerful insights and experience on post larvae production in Latin American hatcheries. This included standard protocols and most common problems during the development of nauplii to post larvae. Each broodstock can be used for 4-5 months, or up to 6 months but with declined fecundity. Causes of non-uniformity of post larvae are attributed to poor water temperature control; genetics; bad feed management (such as using mysis feeds for PL1); and poor water quality management. Control of cannibalism and synchronisation of moulting, temperature control and suitable feeds to maintain the standard survival at 50-55% are critical. In quality assessment, there is zero tolerance for presence of diseases (WSSV, EHP, IHHNV, NHP, TSV, YH, BP, AHPND) or when necrosis is detected, and the stock must be discarded. The stock is discarded when deformities >10%, any mortality in tank and >25% CV (coefficient of variation). PL12 should be at least 4mg. “RAS requires intensive culture but substantial loss of shrimp along the culture period is a major bottleneck in developing this technology,” said Eran Hadas, Maof Hanegev Ltd. He discussed the moulting mortalities at his extremely high-density shrimp farming facility (1,000 PL/m2) in Israel. Histological and microbiome analysis of shrimp did not show any acute bacterial diseases and he attributed the mortality of shrimp to the moulting phase. White faeces disease is responsible for losses of up to 50% in shrimp farms in Central Java, Indonesia. Yustian Rovi Alfiansah, Bremen University, Germany said that causative pathogens were
Vibrio and gregarines. He analysed the microbial populations in faecal strands before and after infection and identified the bacterial types. When disease level was high, so was the gramnegative heterotrophic bacteria Alteromonas populations. In shrimp farming, there is an urgent need to understand the toxicity mechanism of Vibrio parahaemolyticus and VPAHPND toxins, and to develop anti-infective strategies to control AHPND. Vikash Kumar, Laboratory of Aquaculture & Artemia Reference Centre used the gnotobiotic brine shrimp (Artemia franciscana) and freshwater shrimp (Macrobrachium rosenbergii) model. His study provided substantial evidence that the pro-oxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp and freshwater shrimp, M. rosenbergii against the VPAHPND strain. While the discussion was lively, the consensus was that the shrimp sector is growing rapidly and enjoying strong investment and interest. There was great desire in learning from other nations, despite differences in shrimp production systems and methods. Warnings to avoid a “gold rush” and investment bubble was heard and heeded. The importance of high-quality European hatchery production in the near future was well recognised although many hurdles, economic and otherwise, remain. (EAS, 2019). Reference: EAS, 2019. Aquaculture Europe 2019. Summary Report Berlin, Germany, October 7-1. www.aquaeas.eu
RAS for African catfish in Germany I
n Germany, AquaKultur Abtshagen GmbH is the market leader for circulation systems for catfish rearing. Since 2005, it has been building its PAL technology of warm water aquaculture circulation systems, especially for farming the African catfish Clarias gariepinus. The first system went into operation in 2006. In total, it has the technology for commercial hatchery, production and feeding systems for the African catfish. One example is a farm 230 km north of Berlin close to the Baltic coast. In large systems, it is possible to harvest one tank per day which is 1.6 tonnes/fish/day. “RAS farming of the catfish is very profitable. The fish is very robust and can be reared at high density without any effects of stress as they are airbreathers. They are also fast growers. Boneless, the meat is rather delicate in taste like the pangasius fish. In Germany the cost of production in our RAS is around €4-5/kg and market prices can reach €7-8/kg. Direct retail prices can go to €13-18/ kg. The fish is popular as there is already a European catfish which consumers are familiar with,” said Markus Schulz, as he introduced his PAL system at the trade show during AE 2019. He added that the cycle will be 5 months, growing from 16g to 1.5 kg fish. In terms of systems, there is the “PAL-Spezial” 40- foot plug and play container which can produce 5 tonnes/year in 3+2 units within the container, complete with filtration and feeding systems. This can be moved anywhere. More common are larger systems between 5 to 75 m3 production volumes. The largest system can produce 500 tonnes/year. Systems are often custom built in converted old farm houses and can include slaughter, processing and sales at the farm. “The advantages of RAS is that it can be located anywhere. Germany is a cold country and often the heating system is excess heat from biogas. The species of fish must be accepted by the consumers. There is a farm raising tilapia but it is not successful as demand
January/February 2020 AQUA Culture Asia Pacific
Markus Schulz introduced the “PAL-Spezial” 40- foot plug and play container which can produce 5 tonnes/year of African catfish.
was low. Catfish farming has a future in Germany. But we are also looking at developing RAS for another popular freshwater fish and perhaps for the pangasius, which is an interesting imported fish.” The support services offered by the company usually takes over a year to complete, from further investigations into the biology of the fish, setting up the systems to legal approval procedures. AquaKultur Abtshagen also has dispenser feeding technology or fully automatic chain feeders for these systems. The company is also investigating into the ideal feeds for RAS. At the moment, the catfish are fed feeds produced by Coppens, based in the Netherlands and which also supplies the African catfish feed market. www.pal-aquakultur.de