[ usefulness is good, Buffy would like more of it please, so she will be trying to fish.

Slayer reflexes are great when it comes to things that are trying to kill you, but hunting is harder. she has to really focus, to convince her brain that the fish is an enemy.

which might explain why she's standing knee deep in the surf, talking to herself ]

All right, fish. You think you're better than me? Is that it? Well, what's so great about you? So you can swim, that's nothing. I've been swimming since I was in preschool. That's years more experience than you have.