Erne will spend the remainder of the season with the Syracuse Crunch of the American Hockey League on an amateur tryout contract.
The Lightning selected the 6-foot-1, 206-pound left wing in the second round (No. 33) of the 2013 NHL Draft. The 18-year-old had 21 goals and 62 points in 48 games with the Quebec Remparts of the Quebec Major Junior Hockey League. He had one assist in five games for the United States at the 2014 IIHF World Junior Championship.