The incident occurred in the San Francisco Bay near Alcatraz Island.
In the video published on YouTube it is seen how the sea lion several times throws the predator into the air.
"It was a moment like a documentary," SFGate quoted Gorman as saying.
According to vet Cara Field, sea lions often hunt for small sharks. As stated by a specialist, in the video the mammal is trying to stun its opponent and throw it out of the water.