ORIGINAL ARTICLE Aquaculture Effects of n-3 highly unsaturated fatty acid content in Artemia on survival and development of laboratory-reared horsehair crab Erimacrus isenbeckii larvae Tadao Jinbo • Shigeki Dan • Mitsuhiro Nakaya • Masakazu Ashidate • Katsuyuki Hamasaki Received: 7 December 2012 / Accepted: 11 March 2013 / Published online: 31 March 2013 Ó The Japanese Society of Fisheries Science 2013 Abstract The effect of varying levels of dietary n-3 highly unsaturated fatty acid (HUFA) content in Artemia sp. on survival, the number of days required to reach each larval stage, and the growth and morphogenesis of larvae of the horsehair crab Erimacrus isenbeckii were examined. Artemia enriched with materials of six types [condensed Nannochloropsis sp., ethyl oleate, two enrichment levels of eicosapentaenoic acid (EPA), and those of docosahexae- noic acid], and unenriched Artemia were fed to larvae. Newly hatched larvae were reared in groups of 50 indi- viduals in two 2-l beakers until they reached the first crab stage. No significant difference was found in survival rate, growth, or morphogenesis of larvae, but fewer days tended to be required to reach the first crab stage in the group enriched with high EPA compared to the other groups. Results show that, although the amount of n-3 HUFA in unenriched Artemia might meet the demands of horsehair crab larvae for their survival, growth, and morphogenesis, Artemia should be enriched with high EPA to improve the rate of larval development. Keywords Horsehair crab Á Erimacrus isenbeckii Á Larval rearing Á Mass culture Á n-3 HUFA Introduction The horsehair crab Erimacrus isenbeckii is distributed widely throughout the North Pacific, near Japan, mainly along the Hokkaido coast [1, 2]. The stock of this species, which is an important fishery resource because of its high commercial value and its tastiness, has been declining significantly for several decades [1, 2]. These circum- stances have spurred efforts to preserve and manage them as a resource for sustainable utilization. Stock enhancement through the release of artificially produced juveniles into the natural habitat is an attractive option for horsehair crab stock management. Nevertheless, the technical skill required for the mass seed production of this species has not yet been established. Several studies have been con- ducted to investigate larval culture technologies of the horsehair crab larvae. Jinbo et al. [3–5] conducted larval rearing experiments on horsehair crab and reported suitable environmental conditions, such as prey density [3], water temperature [4], and salinity [5]. Even although larval mass cultures to produce horsehair crab juveniles were con- ducted under these appropriate environmental conditions, mass mortality occasionally occurred from the zoeal to T. Jinbo (&) Shibushi Laboratory, National Research Institute of Aquaculture, Fisheries Research Agency, Natsui, Shibushi, Kagoshima 899-7101, Japan e-mail: tjinbo@affrc.go.jp S. Dan Á M. Ashidate Tamano Laboratory, National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, Tamano, Okayama 706-0002, Japan e-mail: sdan@fra.affrc.go.jp M. Ashidate e-mail: ashidate@affrc.go.jp M. Nakaya Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan e-mail: mnakaya@fish.hokudai.ac.jp K. Hamasaki Department of Marine Biosciences, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan e-mail: hamak@kaiyodai.ac.jp 123 Fish Sci (2013) 79:459–467 DOI 10.1007/s12562-013-0618-5