But the Aviva Premiership have moved quickly to replace him, announcing the signings of Cardiff Blues forward Michael Paterson, London Welsh lock Kirill Kulemin and Jersey back-row prospect Charlie Walker-Blair.
Gray, a strong contender to be named in the British and Irish Lions squad, had been linked with a move to Castres for several weeks. But New Zealand-born Paterson, 27, is viewed by Sharks chief executive Steve Diamond as an ideal replacement.
Kulemin, meanwhile, will follow his London Welsh colleague Tom Arscott to Sale next term
"All three are very important signings for us," Diamond said.
"Michael has been outstanding for Cardiff and has been one of their key players over the past few seasons.
"Though Michael has played at number eight predominantly this season, going forward I see him more as a lock for us.
"In terms of Kirill, I know him very well from working with him with the Russian national side. He has played very well for London Welsh this season and has a huge physical presence.
"As for Charlie, he is someone that we have had our eyes on for quite a while now.
"He was out for a year with a knee injury, but has totally recovered from that and has been playing really well with Jersey."
- Sports & Recreation
- Michael Paterson
- Aviva Premiership
- Cardiff Blues
- Kirill Kulemin