Board Thread:Theories and Speculation/@comment-3001903-20160306050607/@comment-1872728-20160306052025

It's possible that the Hoshigaki Clan works similar to the Inuzuka Clan, where they have a standard summoning, so the sharks are probably summoned from somewhere in the Land of Water, maybe an underwater cave or something. He wasn't shown to have the ability to use senjutsu, nor was he shown stationary gathering Natural Energy, so possibly no.