"Cam is going to stay completely in our environment," Witcombe said, adding the injury was a nuisance but not something which would hurt their form.
"We definitely want [Eyre] involved because he's a good leader and we're expecting, just like the Taranaki game, people to step up and play with a lot of ticker."
Eyre's exit from the starting line-up means aggressive Hora Hora lock Miracle Tulua gains his first start - and third cap.
Injury has forced another change to the starting side with Wright's propping partner, Namatahi Waa, dropping out and Mid Western's Willgriff John stepping up.
Witcombe hopes Waa's injury will only be for one game, adding the youngster has justified his selection this season. "He's made some big shifts this year. Coming back home and getting into a semi-professional environment, he's made a lot of shifts.
"He's good in the contact area and in the ruck - he's playing out of position and doing remarkably well for us."
Warren Dunn is promoted from the bench to start, swapping with Troy Gilbert, while Filipo Nakosi gets a start after being out since the win against Wellington nearly a month ago. Nakosi's return is at the expense of Ume Fosita, who joins the bench. Also on the bench are debutantes Dane Rawiri and Jaycob Matiu, who have been added to the squad as cover for Waa and Eyre.
Rawiri and Matiu's promotion into the Taniwha team is a continuation of Witcombe and co's policy to pick from other Northland representative teams when injury strikes.
Taniwha
Ross Wright
Matt Moulds
Willgriff John
Shane Neville
Tom Murday
Miracle Tulua
Kara Pryor
Dan Pryor (c)
Tane Takulua
Dan Hawkins
Jone Macilai
Warren Dunn
Brook Gilmore
Filipo Nakosi
Matt Wright
Reserves: Howard Sililoto, Dane Rawiri, Michael Stolberg, Jaycob Matiu, Kurt Davies, Ume Fosita, Troy Gilbert.