EUREKA, Mo. -- A fingerprint is now required for season pass holders at Six Flags St. Louis.

The St. Louis Post-Dispatch reported that a measurement of the fingerprint will be attached to a bar code on the plastic card to get into the park. Pass holders at the entrance will have to scan both the card and his or her finger to get in. Six Flags began the system more than a week ago when the park reopened for the 2014 season.

The technology known as biometrics has been in use in some other amusement parks such as Disney World and Universal Studios. A Six Flags spokeswoman says that, eventually, it will be at all Six Flags parks across the country.

The new policy at Six Flags St. Louis was a bit of a shock to Jason Kirkpatrick, 38, of south St. Louis County, who visited the park with his 3-year-old son and 5-year-old daughter last weekend. He wasn't clear exactly what bothered him. Maybe it was just one more sign of the erosion of privacy, or concern about where the information could end up. Maybe both.

"You don't know what they can do with it. Or more importantly what someone else could do with it," Kirkpatrick said. "It just feels more personal than a photo."

Six Flags spokeswoman Elizabeth Gotway said the new verification system is only being employed because it's more efficient, allowing patrons to enter the park in less than nine seconds.

She said that the fingerprint measurements taken by a computer could not be used to recreate a patron's actual fingerprint.