'Massive restatement'
"The lack of priests to celebrate the Sunday Eucharist worries us a great deal and invites us to pray and more actively promote vocations," they said in an official declaration.
One bishop from Honduras illustrated the problem by saying he had only one priest for every 16,000 Catholics in his diocese.
Liberal Catholics have suggested that the key to the shortage was making celibacy optional for new priests.
But the bishops' statement called celibacy a "priceless gift" and dismissed the idea of married priests.
Cardinal George Pell of Australia told a news conference the vote was a "massive restatement" of the church's celibacy rule.
The Pope may use the 50 propositions for a possible future document.