Distribution and Population Characteristics of Burbot in the Missouri River, Montana: Based on Hoop Net, Cod Trap, and Slat Trap Captures
Travis B. Horton and Adam C. Strainer
Abstract.—Although burbot Lota lota are native to Montana, little is known about their distribution, life history, and ecology. The objectives of this study were to determine the distribution, relative abundance, and population characteristics of burbot in the upper Missouri River basin in north-central Montana, and to compare sampling efficiency of hoop nets, cod traps, and slat traps. Hoop nets and cod traps were fished in the Missouri River during March 2005 and 2006, and slat traps were fished during March 2006. In total, hoop nets were fished 572 net nights, cod traps for 94 net nights, and slat traps for 92 net nights. Catch rates of hoop nets and cod traps were higher in 2005 than in 2006, and catch rates of all gear types were higher in the upstream half of the study area. Mean section-wide hoop-net catch rates exhibited a significant (P ≤0.05) inverse relationship with increasing distance downstream from Holter Dam, while catch rates for other gear types did not. Catch rates were not significantly different (P ≥0.05) among gear types. The size (length and weight) and condition (relative weight) of burbot sampled was significantly (P ≤0.05) different among gear types. Length, weight, and relative weight were higher for burbot sampled in hoop nets and cod traps than those sampled in slat traps. Slat traps were effective at sampling small (≤300 mm) burbot. Although most (80%) burbot were recaptured within 10 km of where they were tagged, three burbot moved more than 33 km. We hypothesize that the distribution of burbot in our study reach has changed and relative abundance has increased due to the cumulative effect of upstream reservoirs (Canyon Ferry, Hauser, and Holter) by decreasing the downstream water temperature regimen.