Ukupanipo

In Hawaiian mythology, Ukupanipo is a shark god who controls the amount of fish close enough for the fisherman to catch. He occasionally adopted a human child who gains the power to transform into a shark.
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[Polynesian] The Hawaiian shark god who controls the fish by driving them to or from the shores and thus supplying or depriving the people of their food. He is believed to occasionally adopt a human child to whom he grants the power to change into a shark at will.