Olfactory Sensitivity of Pacific Lampreys to Lamprey Bile Acids
Summary
Pacific lampreys Lampetra tridentata are in decline throughout much of their historical range in the Columbia River basin. In support of restoration efforts, we tested whether larval and adult lamprey bile acids serve as migratory and spawning pheromones in adult Pacific lampreys, as they do in sea lampreys Petromyzon marinus. The olfactory sensitivity of adult Pacific lampreys to lamprey bile acids was measured by electro-olfactogram recording from the time of their capture in the spring until their spawning in June of the following year. As controls, we tested L-arginine and a non–lamprey bile acid, taurolithocholic acid 3- sulfate (TLS). Migrating adult Pacific lampreys were highly sensitive to petromyzonol sulfate (a component [...]
Summary
Pacific lampreys Lampetra tridentata are in decline throughout much of their historical range in
the Columbia River basin. In support of restoration efforts, we tested whether larval and adult lamprey bile
acids serve as migratory and spawning pheromones in adult Pacific lampreys, as they do in sea lampreys
Petromyzon marinus. The olfactory sensitivity of adult Pacific lampreys to lamprey bile acids was measured
by electro-olfactogram recording from the time of their capture in the spring until their spawning in June of
the following year. As controls, we tested L-arginine and a non–lamprey bile acid, taurolithocholic acid 3-
sulfate (TLS). Migrating adult Pacific lampreys were highly sensitive to petromyzonol sulfate (a component
of the sea lamprey migratory pheromone) and 3-keto petromyzonol sulfate (a component of the sea lamprey
sex pheromone) when first captured. This sensitivity persisted throughout their long migratory and overwinter
holding period before declining to nearly unmeasurable levels by the time of spawning. The absolute
magnitudes of adult Pacific lamprey responses to lamprey bile acids were smaller than those of the sea
lamprey, and unlike the sea lamprey, the Pacific lamprey did not appear to detect TLS. No sexual dimorphism
was noted in olfactory sensitivity. Thus, Pacific lampreys are broadly similar to sea lampreys in showing
sensitivity to the major lamprey bile acids but apparently differ in having a longer period of sensitivity to
those acids. The potential utility of bile acid–like pheromones in the restoration of Pacific lampreys warrants
their further investigation in this species.