Historical Changes in Large River Fish Assemblages of the Americas

Composition and Changes to the Fish Assemblage in a Large Sub-Arctic Drainage: The Lower Slave River

Ross F. Tallman, Kimberly L. Howland, G. Low, W. M. Tonn, and A. Little

doi: https://doi.org/10.47886/9781888569728.ch3

Abstract.—The Slave River is the largest tributary to Great Slave Lake and the second largest river flowing northward in North America. There are no dams or major industrial developments on the lower Slave River, but further upstream in its Peace and Athabasca tributaries there are numerous pulp mills and a large hydroelectric project (Bennett Dam). These developments appear to have had limited effects on the Slave River fish fauna. The most significant concern is the reduced flood-pulse due to flow regulation, which is hypothesized to have affected spawning success in some species. The other major human impact is from commercial fishing on Great Slave Lake. Migratory species, such as inconnu, have been extirpated from some tributaries due to overfishing. In the Slave River, however, the impact of fishing on inconnu and other species appears to have been less severe. Although the number of age-groups has decreased within some species, the species composition appears to have remained stable. There is little evidence of species introductions into the system, but some rare species, such as chum salmon Oncorhynchus keta, may be extirpated.