The penalties on the trio were attacked as inadequate and "not a deterrent" by the parents of 15-year-old Aimee Wellock, who collapsed and died after running from the gang at a Bradford beauty spot in June.
The ringleader, 18-year-old Clare Carey, was described as a "dangerous offender" by Mr Justice Field at Leeds crown court. He warned her that the sentence was a minimum which could be extended if a parole board review found her unfit for release. Carey has convictions for kicking and punching another girl and assault.
An application by a local newspaper to lift a ban on naming the two younger girls, aged 15 and 17, was refused by the judge. The court had heard that Carey and her friends bought 40 bottles of lager and had a five-hour drinking binge before targeting Aimee and her friends. A postmortem examination found that the girl, a keen dancer, had been suffering from an undiagnosed heart condition which may have been a contributory cause of death.