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reproduction of european eel - towards a selfsustained aquaculture PRO-EEL 5th NEWSLETTER December 2013 Page 4 Ongoing work to improve water qual-ity management has taken a leap towards establishment of suited cul-ture conditions for eggs and larvae. Results obtained in a recent series of PRO-EEL experiments, showed se-vere impact of microbial infection on incubation and rearing success of eggs and yolk sac larvae. Therefore, it is of great importance to control the microbial community. This work provides suggestions for egg disin-fection and microbial control. The final series of PRO-EEL experiments will follow up results, addressing in particular microbial interference and water quality management in feeding larvae rearing culture. Microbial load interfers with the hatch and survival succes by Peter de Schryver, University of Ghent, Belgium. and Sune Riis Sørensen , Technical University of Denmark Cell culture bottles used in experimental in-cubation of eggs and hatch of larvae in mcro-bial interference studies. Photo: Sune Riis Sø-rensen, DTU Aqua Successful protocol for transport of egg by Sune Riis Sørensen , Technical University of Denmark Peter de Schryver, University of Ghent, Belgium. Peter Lauesen, Billund Aquaculture Service, Denmark Terje van den Meeren, Institute for Marine Research, Austevoll, Norway An aim of PRO-EEL was to establish a transport protocol to distribute fer-tilised eggs from the DTU research facility to partners abroad, testing specific larval culture conditions, feeds etc. Transport of viable eggs is common practice in aquaculture, but sensitivity of developing eel eggs to transport conditions was unknown. The tested and established protocol uses 3 L water-filled, zip-lock plastic bags topped with one third of oxy-gen. A monitoring program, record-ing survival of embryos and hatch of larvae, documented that survival and hatch rates transported batches equalled controls maintained at the DTU facility. Transportation times up to 12 hours were applicable, using airplane, car, train and/or ferry. Such protocols allow unbiased, parallel ex-periments on rearing conditions at different places using offspring from the same female. Water-filled zip lock bags topped with oxygen and egg densities around 2000 eggs per litre proved successful. Photo: Sune Riis Sørensen, DTU Aqua Scanning Electron Microscopy (SEM) of the surface of an egg (magnified 5000X). The upper photo shows an egg with noticeable larger bacterial load than the lower picture. Surface area coverage by bacterial colonies, affecting survival and hatch success, is used to quantify bacterial load. Photo: Peter W. Skov, DTU Aqua Studies like this including sampling and rep-licates demand a lot of effort, counting and distributing eggs to bottles. Here, Peter de Schryver, UGent, inspects bottles during ex-periments at DTU’s research facility Lyksvad in Denmark. Photo: Sune Riis Sørensen, DTU Aqua Resistance to transport is limited early in the embryonic development. However, 25 hours after fertilisation, successful shipment is fea-sible. Photo: Sune Riis Sørensen, DTU Aqua


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