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 says the Swedish ship Poseiden, which is taking part in the EU's Triton Mediterranean operation, rescued 439 people from the ship on Wednesday.

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.

The toll was similar to the estimated 40 migrants who died, apparently from fuel fumes, on Aug. 15.

Migrants by the tens of thousands are braving the perilous journey across the Mediterranean this year, hoping to reach Europe and be granted asylum. They are fleeing war, persecution and poverty in the Middle East, Africa and Asia.

The U.N. refugee agency says more than 2,400 people have died at sea so this year.