Question: Manatees are large sea creatures that live along the Florida coast. Many manatees are killed or injured by powerboats. Below are data on powerboat registrations (in thousands) and the number of manatees killed by boats in Florida in the years 1977 to 1990 (how folks who collect these data know the number of manatees killed by boats is unclear to me). Is there any evidence that power boat registrations is related to manatee fatalities?