The U.N. migration agency said Wednesday and added that 83 people swam to shore.
It was one of the deadliest disasters this year among migrants trying to make the perilous journey to Europe.
The boat carrying at least 150 people had been low on fuel while approaching Mauritania, the International Organization for Migration said in a statement.
Survivors were being helped by Mauritanian authorities in the northern city of Nouadhibou, the U.N. agency said.
Survivors said the boat, with women and children on board, had left Gambia on Nov. 27.
An unknown number of injured were taken to the hospital in Nouadhibou.
“The Mauritanian authorities are very efficiently coordinating the response with the agencies currently present in Nouadhibou,” said Laura Lungarotti, chief of mission in Mauritania with the migration agency.
There was no immediate statement from authorities in Gambia, a small West African nation from which many migrants set off in hopes of reaching Europe.
More than 35,000 Gambian migrants arrived in Europe between 2014 and 2018, according to the U.N. migration agency.This notwithstanding the fact that Gambia is small in size.
A 22-year oppressive rule by then President Yahya Jammeh severely affected the country’s economy, especially for Gambia’s youth, and contributed greatly to the surplus of migrants hoping to get to Europe or elsewhere.