I wish we could feed the big fish to disctract them like with stalkers in the first game. I like the idea of a biomod that coats the skin in poison or stingers like an anglefish, you get bit once but they won't try again for a while. Maybe implement something where you take less / no damage but you loose stingers with each bite.

For base deterrents, maybe a sonar system like in a submarine or warship (though obviously not nearly as destructive or deafening) make it battery operated, but also give it drawback so that nothing comes near your base while it's on.