Comparative performances of juvenile Haliotis roei fed on enriched Ulva rigida and various artificial diets

Growth rates of juvenile Haliotis roei fed inorganically enriched Ulva rigida were compared with growth achieved on various artificial diets. Juvenile abalone (20-40 mm SL) were collected from reef platforms off the Perth (Western Australia) metropolitan area and assigned to one of seven different dietary treatments. All diets were fed ad libitum (3% bw day ^-1) every second day, and growth rates were quantified over a 3-mo period. Specific growth rate (SGR) for both shell length and whole body weight indicated that growth of abalone fed enriched U. rigida was not significantly different (P > 0.05) to growth achieved from the best performing artificial diets. A 96-h salinity stress test was also conducted on all treatments to assess the effects of diet on stress resistance. Diet significantly effected survival at 20%, with the U. rigida fed animals exhibiting decreased tolerance to hypo-osmotic conditions (P < 0.05). This may have been caused by an interference with the cell volume regulatory mechanisms normally utilized by Haliotis spp. Enrichment of wild U. rigida increased the algal protein content from 11.4 ± 2% (dry weight) to 32.2 ± 1.5%, perhaps partially explaining the difference in performance between this and other abalone feed trials utilizing Ulva spp. Results indicate that enriched U. rigida is a suitable feed for H. roei, providing similar growth to that achieved from several commercially available diets.