Effect of artificial diets on growth, lipid utilization, and gonad biochemistry in the adult sea urchin Psammechinus miliaris

Three artificial extruded diets of high protein and varying lipid content were manufactured from dried kelp Fronds and commercially available raw materials. The diets were fed to replicate groups of Psammechinus miliaris (Echinodermata: Echinoidea) over a 14-wk period. Survivorship, weight gain, gonad index, and gonad biochemistry were monitored over the duration of the trial. The diets proved palatable to the urchins and were sufficiently stable in seawater for the urchins to consume in tank-based trials. All of the artificial diets enhanced gonad growth as compared to a reference group fed Laminaria saccharina fronds. The satisfactory performance of urchins fed a high-protein diet with a vegetable oil lipid source, composed mainly of oleic and linoleic fatty acids, suggests that P. miliaris is able to utilize effectively diets low in polyunsaturated fatty acids (PUFAs). This has positive implications for the manufacture of cost-effective urchin diet by excluding expensive raw materials (i.e., fishmeal, fish oil).