Isaac Brumaghim was trying to reel in his mackerel tuna when the shark jumped up behind him and attempted to take the fish for itself before going back under the water.
In the video, the panicked man was then seen trying to haul the tuna on board that he wanted for a competition.
But it broke off his line and then disappeared under the surface off Hawaii.
Mr Brumaghim, 37, put his fishing rod away, picked up his paddle, shouted "Oh my God", and starting paddling.
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