Joseph J. Kennedy said he would be leaving Pandora Media after a 9-year tenure. His announcement was made to his Board on Tuesday and in an analyists call on Thursday.  Now the Internet radio service will search for a successor.  The chairman/CEO may be getting out just in time. In September 2012 the stock was pummelled by reports that Apple may launch a rival ad-supported music service. Pandora investors fear that the streaming music service — which tailors selections to users’ tastes — could be crushed by the electronics giant. Pandora has about 150 million registered users, and 55 million of them listen frequently giving it a significant head start over Apple. But payments for music rights eat up about 60% of its revenues which has severely impacted Pandora’s profitability. Since that report, Pandora’s stock has righted itself and the company has posted better-than-expected earnings and growth for its fiscal 4th quarter and full year.