Feed intake and its relation to foregut capacity in juvenile spiny lobsters,Jasus edwardsii

Limited food consumption has been identified as a possible reason for the poor growth in spiny lobsters raised on dry formulated diets. Food intake was determined for different sized juveniles (20–80 g) of the spiny lobster, Jasus edwardsii, fed either fresh mussel flesh or a dry formulated diet for 0.5–5.0 h every 48 h. In addition, the foregut capacities of lobsters of various sizes were measured to relate food intake to foregut fullness. Food intake was relatively rapid on both diets (1 h) and reached mean dry matter threshold values (mean satiation rations) that were related to foregut capacity. Foregut capacity increased linearly with body weight (BW; 10–110 g) and restricted dry matter intake of lobsters to an average of 0.8–1.2% BW regardless of diet. Both wet and dry diets, when fed in equal amount of dry matter, were found to have similar wet weights in the foregut after ingestion. Allowing lobsters more time to feed (2 to 5 h) had no significant effect on mean dry matter intake because the foregut filled to maximum capacity within 1 h. The results suggest that J. edwardsii juveniles have a small foregut capacity (2.5–3% BW) that limits food intake when diets are fed every 48 h. There appears to be no advantage in dry matter intake by providing the nutrient-dense dry formulated diet of this study compared with mussel flesh. Formulated diets would need to be fed more frequently and be highly digestible if they are to deliver sufficient nutrition to maximise growth for commercial aquaculture.