Winter feeding ecology and the importance of cannibalism in juvenile and adult burbot (Lota lota) from the Mackenzie Delta, Canada
2015
Gallagher, C. P. (Colin P.) | Dick, Terry A.
The diet of adult burbot (Lota lota) collected from two locations in the Mackenzie Delta during the winter was characterized using stomach content and stable isotopes analysis (δ ¹³C and δ ¹⁵N). Burbot consumed mainly ninespine stickleback, juvenile northern pike, and conspecifics, with high δ ¹⁵N confirming long-term piscivory. Of the 66 adult burbot sampled, 530 juvenile burbot were enumerated from their stomachs, and from these, 50 juvenile burbot were counted. Many of these juveniles were undigested and were examined for diet content and stable isotopes. Juveniles primarily consumed invertebrates, however, piscivory was detected in young-of-the-year, with stickleback and conspecifics becoming more important as size increased, possibly resulting in competition with adults for small-size fish. δ ¹⁵N indicated juvenile burbot occupied a lower tropic level while δ ¹³C suggested differences in habitat properties between sites. Cannibalism was important to adult diet where the highest frequency of occurrence was 96%, with conspecifics accounting for 82 and 93% of diet items by number and weight, respectively. Cannibalism in burbot increased its trophic breadth and juvenile growth rate, and combined with the amount of conspecifics consumed possibly promoted population stability and coexistence with intraguild predators.
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