Ventral Videographic Assessment of the Feeding Behavior of Juvenile Greenlip [Haliotis laevigata (Donovan, 1808)] and Hybrid (H. laevigata×Haliotis rubra) Abalone in Response to Dietary and Temperature Manipulation

This multifactorial study used a newly developed ventral videography technique to investigate the feeding behavior of 18-mo-old juvenile greenlip abalone (21.1 g, 55.6 mm), and hybrid abalone (23.4 g, 57.6 mm) fed either a formulated commercial diet or live Ulva sp. at 18°C and 22°C. Feeding behavior was scored in terms of the following activities: quiescence, alertness, moving, feeding, distance traveled, velocity, and homing. There was a significant effect of diet type and temperature on feeding behavior of abalone. Both types of abalone were more active and exhibited the highest velocity when fed the formulated diet at 22°C. Greenlip abalone spent a larger proportion of time feeding on Ulva sp. than on the formulated diet, regardless of the water temperature. In contrast, no significant difference was observed in the proportion of time feeding between diet types for hybrid abalone. Both types of abalone rapidly located and consumed Ulva sp. when feed was introduced into the aquaria at 1600 h (light phase). In contrast, abalone predominantly commenced feeding on the formulated diet in the dark phase, indicating the potential of Ulva sp. as feed attractant in abalone diet, to promote feeding. The mode in which abalone consumed feed also differed between diets. Abalone fed the formulated diet nibbled intermittently on random chips, whereas when fed Ulva sp., abalone engulfed entire individual fronds before moving on to the next available frond. Greenlip and hybrid abalone exhibited homing behavior at the completion of the dark phase, which was more pronounced in abalone fed Ulva sp. This new information may assist in refining feed design and feeding practices for the culture of these two types of abalone.