JOHANNESBURG — The remains of 52 people have been found after more than 100 migrants went missing off Djibouti when two boats capsized in rough waters, the United Nations migration agency said Wednesday.

Witnesses said large waves had caused the overloaded boats to tip over about a half-hour after they departed on Tuesday. The United Nations agency, the International Organization for Migration, said its team had found an 18-year-old survivor who reportedly boarded a boat with 130 people, including 16 women.

No details were immediately available about the second boat, but a search-and-rescue operation was said to be underway.

Thousands of migrants from the Horn of Africa region, most of them from Ethiopia, set off every year from Djibouti to cross the Bab al-Mandab Strait for the Arabian Peninsula with hopes of finding work in rich Gulf countries.