ROME (AP) — About 50 bodies were found in the hull of a migrant boat that was rescued off Libya's northern coast Wednesday, adding to the more than 2,400 people who have perished at sea this year making the dangerous Mediterranean crossing to Europe.

Italy's coast guard said the Swedish ship Poseidon, which is taking part in the EU's Triton Mediterranean operation, rescued 439 survivors from the ship.

The rescue was one of 10 requests for assistance that arrived at the coast guard's operations center as Libya-based smugglers take advantage of calm seas to send boats overloaded with migrants to Europe. Boats in distress use satellite phones to call coast guard rescuers or are spotted by patrolling Italian military aircraft.

Wednesday's toll was similar to the 49 migrants who died, apparently from fuel fumes, on Aug. 15 when some 320 other survivors were rescued.

Migrants by the tens of thousands are braving the perilous journey across the Mediterranean, hoping to reach Europe and be granted asylum. They are fleeing war, persecution and poverty in the Middle East, Africa and Asia. Once in the lawlessness of Libya, they pay smugglers upward of 1,000 euros ($1,150) to be crammed into overcrowded and unseaworthy ships and dinghies for the crossing.

The U.N. refugee agency says more than 2,400 people have died at sea so far this year making the crossing. More than 110,000 migrants have been rescued and brought to southern Italian ports.

This story has been corrected to say 49 migrants, not 40, died in the incident on Aug. 15 and that the name of the Swedish ship is Poseidon, not Poseiden.