The UN migration agency says the boat sank on Friday between a Comoros island and the French island of Mayotte.
At least 30 minors were charged with treason and inciting a military coup after they took part in August protests.
Scenes of young Nigerians fainting while in court in the capital Abuja sparked uproar from politicians, civil society.
Sipho ‘Hotstix’ Mabuse on the power of art in South Africa’s struggle for freedom and its relevance to today’s conflicts