Population Structure and Diet of Burbot (Lota Iota) in Small Streams Near the Southern Extent of the Species' Range

ABSTRACT

We studied the population structure and diet of burbot (Lota lota) listed as state-endangered and inhabiting small streams near the southern extent of the species' North American range. The size structure was truncated, with a mean total length of 191 mm and range of 84–356 mm. A subsample of individuals (n=32) were euthanized, and age estimates from otoliths revealed surprisingly short lifespans (maximum age of five years). An age-length key was then used to assign ages proportionately to the larger sample. and 80% were estimated to have been age 2 and age 3. Burbot stomach contents were removed with gastric lavage from 120 individuals during summer sampling that occurred at four-hour intervals for 24 h. Burbot specialized on Ephemeroptera, and consumed a variety of other invertebrate prey; surprisingly. fish were only found in three individuals. While similar to other reports of burbot in small streams, (e.g. small body sizes, earlier maturation, short- lifespan, invertebrate-centered diet) the population demographics were considerably different from ‘typical’ burbot populations occurring in lakes, large rivers, and reservoirs.