White abalone (Haliotis sorenseni), a critically endangered gastropod native to California, faces ongoing population collapse due to overfishing and habitat loss. Conservation aquaculture and outplanting are central to recovery, but success is constrained by unusually high early-stage mortality and slow growth relative to other species. While hatchery programs for species such as pinto abalone often achieve first-year survival rates near 10%, survival in white abalone is typically <1%, with few juveniles reaching outplant size. This pattern highlights that existing husbandry protocols, largely adapted from other haliotids, fail to meet the unique physiological and nutritional needs of H. sorenseni. Juveniles <3 mm depend on microalgae, but optimal algal diets for this species remain undefined. This study evaluates the effects of microalgal diets on juvenile growth and survival under controlled rearing conditions to identify species-specific nutritional strategies. Optimizing early diets has the potential to improve growth and survivorship, shorten culture time, reduce rearing costs per unit animal, and enhance the overall effectiveness of restoration programs for this critically endangered species.