Santo Domingo.– Ferry service between the west Puerto Rico port Mayaguez and the Dominican Republic will stop operating on April 15, a measure that will be until they Ferries del Caribe can resolve the impasse with the Port of Mayaguez administration.
According to Liana Pena, the company’s executive vice-president, if the conflict is solved, they would resume passenger service in December. The ship Caribbean Express will sail on April 15 for the last time on the Mayaguez-Santo Domingo route.
The Caribbean Express carries about 170,000 passengers, 19,000 passenger vehicles and 11,000 trucks annually.

Good question WP!
Bet the impasse is a matter of port fees. That there is a bad taste left in the mouth of the the Port of Mayaguez administration over the decison of Ferries del Caribe to move its homeport to San Juan.
The only winner here will be the airlines.
Point of information:
The main Airport is in Carolina not San Juan.