Burbot (Lota lota) exhibit plasticity in life-history traits in a small drainage at the southwestern-most extent of the species’ native range

Little is known about the life-history traits exhibited by burbot (Lota lota) throughout their circumpolar range. Monitoring PIT-tagged burbot between lentic and lotic habits and collection of demographic data (length, age, sex, and maturity) were used to answer the following questions in the Torrey Creek drainage of west-central Wyoming, USA: 1) is there plasticity in the life-history traits of the burbot population, 2) do Trail Lake origin and Torrey Creek origin burbot interchange during the spawning period, and 3) is there a difference in growth and age at sexual maturity between Trial Lake and Torrey Creek? We found plasticity in life history traits exists within a burbot population in a small drainage at the southwestern-most edge of the species native range. Directional migration of PIT-tagged burbot in Trail Lake and Torrey Creek was monitored nearly continuously by tandem stream-width antennas. Thirty-five percent of lentic-origin burbot migrated upstream into Torrey Creek, and 11% of lotic-origin burbot migrated downstream of the antennas near the Torrey Creek inlet to Trail Lake. Migratory activity of burbot was highest during the late winter and early spring at a time that coincided with spawning. Additionally, Torrey Creek-origin burbot were smaller and younger than Trail Lake-origin burbot. In addition to documenting migration, the sampling of small, sexually mature burbot in Torrey Creek suggests that stream-resident burbot reach maturity earlier than adfluvial and lacustrine burbot in Trail Lake. Furthermore, high catch rates of age-0 burbot indicate that Torrey Creek upstream from Trail Lake provides nursery habitat to the burbot population. Life history trait plasticity and spawning and nursery habitats documented in this study must be considered when selecting conservation actions for this unique burbot population.