Food, growth, habitat, and community interactions of young-of-the-year burbot, Lota lota L., in a Precambrian Shield lake

Abstract

The burbot, Lota lota, is a widely distributed gadid of the northern circumpolar regions of North America and Eurasia. Despite its near ubiquity over much of its range, relatively little is known about its biology during the first year of life.

Burbot sac-fry of 3 mm total length, hatched under the ice in early May in Shebandowan Lake. Their first foods following atrophy of the yolk-sac were copepods and cladocerans which they captured pelagically. At first the fry swam in small schools, high in the water column of the near-shore littoral, and fed during the daytime. Upon reaching 30 mm in total length, the burbot fingerlings became solitary and benthic, and fed primarily at night, almost exclusively on the amphipod, Hyalella azteca. Amphipods constituted about 75 per cent by number of all the food consumed by burbot fingerlings in their first year of life. Growth was rapid from May to the end of July, tapered off during August to October, and effectively stopped by November at freeze-up. The principal habitat of burbot fingerlings during the benthic stages of their life was the near-shore littoral, in depths ranging from 0.5 m to 4.0 m. There, they were sheltered by boulder shoals, sunken trees or other debris, or beds of quillworts (Isoetes sp.). The principal ichthyofauna that cohabited with the burbot included the sculpin (Cottus cognatus), the smallmouth bass (Micropterus dolomieui), two etheostomatines (Etheostoma nigrum) and (E. exile) and the yellow perch (Percaflavescens). Burbot fingerlings were subjected to low levels of prédation from the nocturnal foraging of walleyes (Stizostedion vitreum).