Morphological and ecological variation among populations and subspecies of Burbot (Lota lota [L, 1758]) from the Mackenzie River Delta, Canada

Résumé

The Burbot (Lota lota [L, 1758]) is a holarctic distributed freshwater fish in the Gadidae family. In northwestern Canada, it has an important value for local and traditional fisheries. We describe the morphology and ecology of Burbot from four populations in the Mackenzie River Delta. Two subspecies come into contact in this area, which is the western edge of Lota lota maculosa distribution (one population in our study) and the eastern edge of Lota lota lota distribution (three populations in our study). We found the combined length–weight relationship in these four populations to be log₁₀ (weight) = −3.986 + 2.617 * log₁₀ (length). There was no difference in mean body length (overall mean and standard deviation 73.4 ± 8.7 cm), although the L. l. lota populations were heavier than the L. l. maculosa population. All populations differed in their carbon and nitrogen stable isotope signatures (δ¹⁵N overall mean 12.1 ± 1.59; δ¹³C overall mean −25.54 ± 1.11). Main prey items were four fish species: Ninespine Stickleback (Pungitius pungitius [L, 1758]), Broad Whitefish (Coregonus nasus [Pallas, 1776]), Burbot, and Northern Pike (Esox lucius [L, 1758]). Ecological and morphological differences may be due to local conditions and population variability or to the different Lota lota subspecies. More ecological and morphological information from this region is needed to resolve possible phenotypic differences between the subspecies.