Silver Lamprey - Reproduction and Life Fycle

Reproduction and Life Fycle

Adult silver lampreys move upstream to spawn in May and June, when the water temperature reaches 50 °F. Using their mouths to move sand and gravel, they dig a nest in the stream bed. Once the nest is completed, the female attaches herself to a rock and the male attaches to her head, wrapping his tail around hers to bring the genitals close together. Eggs and sperm are released, then the pair separates. Once spawning is completed and the eggs are deposited in the nest, the adults die. Upon hatching, the larvae (called ammocoetes) are blind, toothless, and provided with a fine-mesh tissue sieve. They drift downstream and burrow in the sand, mud, and organic material for 4–7 years. During this time, the ammocoetes feed mostly on detritus and algae. When they are approximately four to five inches long, the ammocoetes metamorphose into parasitic adults and migrate downstream to search for hosts. After one to two years feeding as a parasite, adult silver lampreys move upstream to spawn and die.