The average number of people in custody in Castlerea prison last year was just over three hundred.
According to the Annual report from the prison service, the capacity of the Roscommon jail at the end of last year was 340.
Loughan House in Cavan also had an average prison population at the end of last year of 104, out of 140 available bed spaces.
12 prisoners in Castlerea were on temporary release while two prisoners in the Blacklion open prison were on temporary release.