Senegal’s navy says it has intercepted four boats over three days with more than 600 people on board.
They were attempting the treacherous crossing to Spain’s Canary Islands – a gateway to Europe.
Footage on social media on Saturday showed other would-be migrants jumping off a boat that had run aground in Senegal’s coastal city of St Louis.
Witnesses say winds forced them back and they wanted to avoid arrest by the navy, which has stepped up patrols.
“We were at the beach chilling when suddenly we saw a pirogue [wooden style boat] arriving with migrants on board. When they got closer to the shore, they were frantically jumping into the water,” a 19-year old Saint Louis resident told the Reuters news agency.