MADRID — Spanish authorities say rescuers have found five dead migrants and 53 survivors in a boat partially sunk in waters east of the Strait of Gibraltar.

The Maritime Rescue Service said Thursday that a surveillance plane found the dinghy in a stretch of the Mediterranean known as the Alboran Sea on Wednesday. The bodies and survivors were taken to Almeria.

The service said that 181 northern African migrants — mostly adult men — were rescued Thursday morning from five boats attempting the shortest route into Europe.

On Wednesday, a total of 501 people were pulled from 12 boats, with three migrants found crossing the Alboran Sea in a jet ski.

A recent spike in migrant arrivals has put a strain on public services and added pressure to the Spanish government.