“The Thermocline Trap

Why do fish suddenly show up where you don’t expect them? One day you’re marking bait balls at 20m… the next day a pelagic smashes your lure on the surface, and then out of nowhere someone hooks a tuna right on the bottom. It feels random — but it isn’t. Fish constantly change depth because they’re chasing three things: 🟦 Temperature — Every species has a preferred thermal band. When warm or cold water layers shift (thermocline drops, upwelling rises, or a warm eddy pushes in), pelagics follow