When on the pier or on a boat you want to look for the birds diving at the water in groups.This usually means that something is chasing the bait fish up to surface you just cast on them and you should hook up. Usually this happens with bonito, cobia, and other. Cobia usually swim in groups and they scare easily. So dont cast right on them cast over them then reel it in through them.
This is a cobia if you see a big group while at pier do what I said above.
Kings usually like fast moving lures.
Spotted trout like shrimp live or dead and lures should also work.
Sharks live in deeper water and also love eating bonitas heads.