The shark tore off the boy's limbs and part of his stomach as he was surfing early today morning in an off-limits section of sea off the west coast of the island.
The boy, whose first name was given as Elio, was a keen and promising surfer.
It was the 16th shark attack on the island since 2011 and the seventh loss of life.
Authorities immediately put in place a "post-attack procedure" in a bid to capture the shark.
In February, island authorities extended until February 2016 a law prohibiting swimming and other water-based activities such as surfing and windsurfing except in special areas.
This measure has resulted in a dramatic decline in tourism on the island lying to the east of Madagascar.