Suitability of two seaweeds, Gracilaria lemaneiformis and Sargassum pallidum, as feed for the abalone Haliotis discus hannai Ino

The suitability of two algae species, Gracilaria lemaneiformis and Sargassum pallidum, for use as food sources for the abalone Haliotis discus hannai Ino was evaluated. Abalones were fed one of five experimental diets: 1) kelp Laminari japonica: 2) G. lemaneiformis: 3) S. pallidum; 4) a mixed diet of L. japonica and G. lemaneiformis (1:1); and 5) a mixed diet of L. japonica and S. pallidum (1:1) for a period of 4 months. The survival, growth (shell length and body weight), condition index (body weight/shell length), and feed utilization were measured. Survival was excellent (100%) in all groups. Growth rate (body weight) was highest in the abalone fed kelp exclusively, followed by the mixed diet of kelp and G. lemaneiformis. The abalone fed S. pallidum had the lowest increase in body weight and the lowest feed intake. The mixed diet of kelp and G. lemaneiformis yielded the biggest increase in shell length. There were no significant differences in the condition index among all the treatment groups. The mean daily feed intake of L japonica was highest, followed by the mixed diets of kelp and G. lemaneiformis, and was lowest for S. pallidum. Abalone exhibited a preference for L japonica. The feed conversion efficiency was highest for G. lemaneiformis. Results suggest that G. lemaneiformis can be used as a partial substitute for kelp in the diet of cultured abalone. (C) 2010 Elsevier B.V. All rights reserved.