Habitat Use and Seasonal Migrations of Burbot in Lowland Rivers in North France
Alain Dillen, Johan Coeck, and David Monnier
Abstract.—Our objectives were to study habitat use of different life stages of the burbot Lota lota L. in lowland rivers and to develop habitat models to assess possible reintroduction sites in Flanders, Belgium. Summer habitat use of subadult and adult burbot was studied in lowland rivers in northeast France in the Meuse basin. Highest burbot densities were found in the upper river parts over several watersheds. Adult and subadult burbot showed a strong preference for microhabitats characterized by undercut banks and cover by tree roots. Habitat use of larvae and fingerlings was studied in spring. Both larvae and fingerlings were exclusively found in small tributaries (width < 2 m). Fingerlings mainly occupied tributaries with low to moderate flow velocity (0.05–0.15 m/s) and high densities of vegetation (>25%). Winter spawning migration was studied using fyke nets. Adult burbot migrated into the deepest tributaries and upstream migration was highest at increased water levels or flows. Analysis of water quality requirements revealed that both nitrate (NO3–) and total nitrogen (Nt) content negatively influenced burbot densities. With these results, two models to evaluate habitat suitability of lowland rivers for burbot were developed and tested. The use of these models to evaluate potential reintroduction sites for burbot in Belgium is discussed.