A five-year-old girl was among the nine people that were saved, while scores more remain unaccounted for.
According to survivors, the traditional fishing boat carrying 170 passengers sailed last week from the Senegalese-Gambian border region. It overturned near the southwest coast of Mauritania.
Thousands of boats left Mauritania last year as a major transit country for migrants attempting to go from West Africa to Europe.
The Canary Islands of Spain are the most popular destination along this treacherous path.
According to the Spanish government, there were around 40,000 new arrivals last year, which is twice as many as the year before.
Migrants frequently sail in overcrowded boats in their desperation to reach Europe.
The Caminando Fronteras organization believes that in the first five months of 2024, over 5,000 migrants perished while attempting to reach Spain by sea.
The European Union provided Mauritania with €210 million (£177 million; $225 million) in aid in April; about €60 million of that amount will go toward combating unauthorized immigration to Europe.
