Marine Aquaculture in Israel with Special Emphasis on Larval Rearing

AbstractThe goal of mariculture research in Israel is the development of an industry, based on available sea and brackish water, in the Arava Desert, the Gulf of Eilat and along the Mediterranean coast. Urgent progress is needed due to the shortage of fresh water for agriculture. High priced euryhaline fish like Sparus aurata and Dicentrarchus labrax are the obvious choice for development along with the more common grey mullet Mugil cephalus. The aim of this paper is to present the research and zootechnical state of the art in Sparus aurata and Dicentrarchus labrax larval rearing at the National Center for Mariculture (NCM).Fertilized eggs are stocked in 600 L tanks and hatching success estimated from aliquot counts. Rearing continued for 32 d after which larvae are removed from these tanks with minimum mortality. Under normal rearing conditions these tanks produce 15‐35 32 d old (10 mg, ww) Sparus aurata larvae/L (20‐40% survival). Average seabass survival to 80 mg (40 d) is 35%. Tanks were continuously supplied with filtered (10 μm), temperature and salinity controlled seawater and freshly enriched food organisms through a special delivery system. This system was recently upscaled to 1,700 L tanks with equally good results for seabream larval rearing.Live food enrichment regimes for the two species were developed to maximize their growth and survival. A microdiet is presently being used from the age of 20 d. The problems involved with using dry diets with larvae were found to be associated with both their digestibility and attractivity.As a result of a salinity reduction from the ambient 40 to 25 ppt, swim bladders developed in 90% of seabream and 75% of seabass. In addition, growth rate of larvae improved by 15%. Finally, seabream tend to show strong aggressive behavior once size differences in the population of 32 d larvae is greater than 300%. Therefore, once seabream ended their 32 d hatchery period they are graded to three size groups of 5, 10.3 and 23 mg (ww). The graded fish are counted with a locally developed Computer Aided Fish Counter (CAFIC) and stocked separately in 5 m3 nursery tanks.