KOTHIARY, Senegal—Less than a month after mourning a neighbor killed on the 3,000-mile migrant trail to Europe, Ibrahima Ba set off on the same treacherous road.

The 27-year-old was supposed to build a future in this stable corner of rural Africa, using money sent from his father in France to raise bulls and sell diesel fuel. But in March, as chaos in Libya eased a pathway to the Mediterranean, Mr. Ba gambled he could make a better life, selling the cattle to buy a ticket along the world’s deadliest migrant route and joining the largest global migration wave since World War II.

In April, Mr. Ba’s family mourned him, too: they believe he drowned alongside 700 migrants aboard a trawler that tipped into the sea, the worst in a series of tragedies that shocked Europe and triggered frantic diplomacy to rethink European immigration laws.

At least 1,840 have died on the crossing from Libya to Italy so far this year, following 3,200 known deaths last year, the International Organization for Migration says.

“He didn’t lack for anything, he had everything he needed,” said Mr. Ba’s mother, Awa Diop. “But he wanted to have his own means.”