A boat carrying around 40 migrants and refugees has sunk off the coast of Mauritania, leaving only one survivor, according to the United Nations refugee agency UNHCR. The perilous sea passage from West Africa to the Canary Islands was once a major route for migrants seeking jobs and a better life in Europe. Attempts became scarcer when Spain stepped up patrols in the mid-2000s, but the route is seeing a fresh surge. "New shipwreck off the coast of Nouadhibou #Mauritania of approximately 40 persons on board, there is one survivor (from Guinea)," tweeted UNHCR special envoy Vincent Cochetel. UNHCR "along…