Depending on how long each Lamprey spends in the larval and parasitic phases, they can spawn at ages ranging from 4 to 8. A Lamprey can mature into an adult at the age of 3 and reach sexual maturity at the age of 4 after finishing its parasitic stage a year later. If the Lamprey converts after six years and stays a parasite for an additional two years, it can take up to 8 years.