But the Robins boss has also confirmed that the hunt has begun to find a replacement for the 30-year-old.
“We are disappointed to lose a player of Mick’s calibre but he has been a great servant to the club during his time here and he leaves with our best wishes for the future,” Chester told his club’s official website.
“He’s been a great leader for this club and this is not the way he would have wanted to end his career, but he’s played at the highest level and can be rightly proud of what he’s achieved in the game.
“The time has come for him to put his family and life after rugby first and he’s made the right decision.
“He’s a true professional and he wouldn’t have been happy being on the sidelines and not being able to make a contribution on the field.
“That’s the sort of bloke he is and it’s been a pleasure working with him.
“We’ve already begun the search for a replacement for Mick and we’re looking both in this country and overseas. We now have a full quota spot to play with but we won’t be rushing into any decisions.
2We have a really close-knit squad this year and whoever we bring in will have to fit in both on and off the field.”