Callahan, 22, made his NHL debut on March 25 against the Columbus Blue Jackets. He was second on the Grand Rapid Griffins of the American Hockey League with 26 goals and fourth with 44 points in 70 regular-season games.
Callahan was a sixth-round pick (No. 180) in the 2009 NHL Draft.
Nestrasil, 23, had 16 goals and 36 points in 70 games for the Griffins. He was a third-round pick (No. 75) in 2009.
I have been blessed to play for 16 years in the NHL; it has been an amazing ride. I would like to thank the Tampa Bay Lightning and New York Rangers organizations and owners for providing me the opportunity to play the sport I love for so many years. I could have never played for so long or accomplished all that I have without the unwavering love and support from my wife, Heather, our three sons, Ryan, Lucas, and Mason, and my parents.
— Martin St. Louis after announcing his retirement from the NHL on Thursday