The U.S. Conference of Catholic Bishops are screening priests who provide ministry to cruise lines in an effort to eliminate unsuitable clergy, such as those who were suspended for sexual abuse or those who have left the priesthood,  reported the Associated Press.

Formerly, priests on cruise ships were not regulated by the USCCB, and cruise lines were not doing background checks.

The conference has approved more than 650 priests to work on cruise lines since the program began a year ago, reported the AP. The priests must have their local bishop’s approval and undergo a yearly review.

Two cruise lines – Celebrity and Holland America – currently have priests approved by a Catholic ministry called Apostleship of the Sea.

However, the report stated that other cruise lines hire clergy privately or use agencies, such as Rent-A-Priest, which provides former and now-married priests, who are no longer authorized to celebrate Mass.

The USCCB hopes all cruise lines will adopt a better screening process for clergy.