Abstract
We characterised seasonal and ontogenetic changes in diet and prey energy density of rainbow trout ( Oncorhynchus mykiss ) in Lake Rotoiti, New Zealand, to better understand the prey requirements of trout in central North Island lakes. Common smelt ( Retropinna retropinna ) was the dominant prey item of rainbow trout larger than 200 mm (77.8% of diet by weight), followed by kōura (freshwater crayfish Paranephrops planifrons ; 6.3%), common bully ( Gobiomorphus cotidianus ; 5.5%), and kōaro ( Galaxias brevipinnis ; 3.4%). Juvenile rainbow trout (