Spyderco have a lot of good SALT series folders. The stuff made from LC200N will actually hold an edge long enough to get some use out of it, compared to H1. I'd love to have a Spyderco Caribbean, but probably not on a fishing boat, where I'd be worried about losing it.
Morakniv have a cork knife that's more of a clumsy boater knife than something a fisherman would probably want. The Kansbol or Grohmann #3 Boat Knife would be a good blade for a fisherman. If you want upscale stainless and you want to go all in, get yourself a Demko FreeReign in Magnacut steel.
As others have mentioned, maybe bringing a sharpening stone wouldn't be a terrible idea if a knife is going to be used a lot.