Diet of rainbow trout in Lake Rotoiti: an energetic perspective

作者：Blair J M^*; Hicks B J; Pitkethley R; Ling N

来源：New Zealand Journal of Marine and Freshwater Research, 2012, 46(4): 557-565.

DOI：10.1080/00288330.2012.707660

• New Zealand
• predator-prey relationships
• energy density
• Oncorhynchus mykiss
• Retropinna retropinna
• Paranephrops planifrons
• Gobiomorphus cotidianus
• Galaxias brevipinnis

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 koura (freshwater crayfish Paranephrops planifrons; 6.3%), common bully (Gobiomorphus cotidianus; 5.5%), and koaro (Galaxias brevipinnis; 3.4%). Juvenile rainbow trout (%26lt;200 mm) consumed amphipods, aquatic and terrestrial insects, oligochaetes, tanaid shrimps, and smelt. Trout consumed koaro only in autumn and winter; consumption of other species did not vary seasonally. The maximum size of smelt consumed increased with increasing trout size, but trout continued to consume small smelt even as large adults. Consumption of larger prey items (koaro and koura) also increased with increasing trout size. This study indicates the importance of smelt for sustaining rainbow trout populations, as predation on other species was relatively low. These findings provide a basis for bioenergetic modelling of rainbow trout populations in lakes of the central North Island of New Zealand.

• 出版日期2012