Bishop Paul Connell says a lot of the existing priests are ageing.
A number of parishes in a Shannonside diocese will be clustered next year due to the retirement of long-serving priests.
This relates to the Diocese of Ardagh and Clonmacnois, which includes Athlone, Ballymahon, Carrick-on-Shannon and Longford.
There has been a lack of vocations over the past decade.
Bishop Paul Connell says a lot of the existing priests are ageing and some parishes in the diocese have already been clustered.