Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

Pacific Lamprey Ammocoete Habitat Utilzation in Red River, Idaho

Christopher W. Claire, Timothy G. Cochnauer, and George W. LaBar

doi: https://doi.org/10.47886/9781888569896.ch15

ABSTRACT The Pacific lamprey Lampetra tridentata is a native Snake River basin fish species occupying a unique ecological niche. The recent decline in numbers of returning Pacific lamprey adults to the Snake River basin has focused attention on the species. In 2000–2002, we employed electrofishing surveys to determine habitat utilization and distribution of Pacific lamprey ammocoetes in Red River, South Fork Clearwater River drainage, Idaho. Ammocoete average densities were 25.7/100 m² in scour pools, 4.4/100 m² in riffles, 2.1/100 m² in rapids, and 253.3/100 m² in the one alcove sampled. Ammocoetes were found in water depths ranging from 1.0 cm to 1.0 m; however, the two greatest densities were observed in habitat units with maximum depths greater than 0.50 m. Pacific lamprey ammocoete density decreased with increased velocity and coarse substrate, and increased with fine and medium substrates and riparian shade.