A boat carrying around 40 migrants has sunk off the coast of Mauritania, leaving only one survivor, the United Nations refugee agency UNHCR said on August 6. #UPDATE About 40 people are feared dead after a migrant vessel sank off the coast of #Mauritania, the UN refugee agency said on Thursday https://t.co/ZQ456betyC pic.twitter.com/EPCRiDsgq2 — AFP…