COMPARATIVE-STUDIES ON THE NUTRITION OF 2 SPECIES OF ABALONE, HALIOTIS-TUBERCULATA LINNAEUS AND HALIOTIS-DISCUS-HANNAI INO .1. EFFECTS OF ALGAL DIETS ON GROWTH AND BIOCHEMICAL-COMPOSITION

This study was conducted to examine the nutritional value of eight alg al diets for two species of abalone, Haliotis tuberculata and Haliotis discus hannai, by measuring biochemical composition of the algae and relating this to feeding rate, growth and biochemical composition of t he animals. Nutritional value of algal diets can be divided into three categories for each species of abalone. For H. tuberculata the best p erformance was on the mixed diet and Palmaria palmata intermediate was Alaria esculenta, Ulva lactuca and Laminaria digitata, and lowest gro wth was on Laminaria saccharina and Chondrus crispus. For H. discus ha nnai, best performance was on A. esculenta, P. palmata and the mixed d iet; intermediate was on L. saccharina and L. digitata and lowest was on U. lactuca. It is generally accepted that high ''balanced'' levels of protein (> 15%), lipid (3-5%) and carbohydrate (20-30%), with no de trimental substances in natural algae are essential for optimal growth performance of these abalone. The fact that A. esculenta, L. sacchari na and U. lactuca had different dietary values for the two abalone spe cies indicates specific nutritive requirements and/or digestive physio logy. Overall, H. tuberculata grew faster, had higher food conversion efficiencies and muscle yield than H. discus hannai. Generally abalone fed on the highest category diets, had higher muscle yields and level s of protein, visceral lipids and muscle carbohydrate. Viscera and foo t muscle are reservoirs for lipid and carbohydrate, respectively. The effect of algal diet on sexual maturation is similar to that on somati c growth.