Fontenot came on board in 2006 as a coaching intern and advanced to assistant offensive line coach (2007-10), running backs coach (2011) and tight ends coach (2012-15).
"It's been a pleasure to work with Jerry for the past 10 seasons," Packers head coach Mike McCarthy. "He has given a lot to this organization and has been a big part of our success."
Gash came to Green Bay in 2014 as running backs coach after serving mostly in the same position from 2007 to 2012 with the Detroit Lions. He also was an assistant special teams coach and assistant running backs coach for the New York Jets in 2005 and 2006.
"I would like to thank Sam for his contributions to the team over the past two seasons," McCarthy said.
Gash said he was given the news earlier in the day.
"I respect the Green Bay organization a lot," Gash told the Milwaukee Journal Sentinel. "I just apologize that I didn't, I guess, get the job done. And that's totally on me. You just live and learn from every situation that you're in. I'm living and I've learned a lot. That's all. I think the organization is great."
McCarthy said after the Packers' season-ending loss to the Cardinals in the NFC divisional round of the playoffs that he was unhappy with the offensive coaching staff this season.
"We did not get it done on offense," McCarthy said. "So the structure was obviously a part of the failure on offense. That's something that will be closely evaluated."