Durham coach Jon Lewis says all-rounder John Hastings will be difficult to replace, with shoulder surgery set to rule him out for the 2016 campaign.
The Australian, 30, will go under the knife once his stint in the Indian Premier League finishes in May.
Hastings took 76 wickets in all competitions for Durham last season.
"He's going to need surgery followed by some period of rehab which is going to take him out of all if not most of our season," Lewis told BBC Newcastle.
"He's a difficult guy to fill. It comes down to a lot of things, finding the right person, finding the right calibre of player, finding the person who can fulfil the roles he did for us in terms of the overs that he bowled," he added.
"In the white ball stuff he's one of the leading bowlers."
The 2013 County Champions have already enquired about signing South African paceman Kagiso Rabada as a replacement.
But Lewis also wants the club's younger pace bowlers to step up.
"We need to make sure that we develop our own players from within so whether that provides some more opportunities for our locals, that needs to be looked at," he added.
"Last year I was concerned with overworking young seamers but they are now a year older and maybe we can look to get more out of them."