Turkey is the only country that recognises Northern Cyprus and all the trade goes vis Turkey. Due to its proximity, Mersin is one of, if not, the main port for trade to and from Cyprus. With the lack of development in Northen Cyprus, there is a large trading deficit between it and the mainland. Many of the ships returning to Turkey are almost empty. With that trade differential, the freight cost from the island to the mainland is far cheaper than to the island. All of this may change in the future with the EU-Cyprus machinations.
FOOTNOTE: The search was called off. Unfortunately 2 crew members are still missing, presumed drowned.