We were bringing in a big halibut (~60")when a sea lion took it. He slapped it around on the surface for a bit. My boat captain said it's not uncommon. They hang around fishing boats knowing they might steal an easy catch. In our case, our captain was pissed off and navigated over to the sea lion and basically ripped the halibut out of it's mouth. It was questionably legal but made for an awesome story.