With Kauai's abundant 63 miles of accessible beaches, there are plenty of spots to set up a pole and catch some dinner or find the closest pier and set up there. No license is required for shoreline fishing here on Kauai. The only thing you need to bring, buy here, or rent is your tackle. You can run lures, bait (shrimp, squid, or fish scraps, which can all be found at Big Saves), or live bait. Live bait can be scarce, so best thing is to buy some shrimp and find a school of small bait fish, snag one and rig it up to your biggest pole with a larger weight and hook. This will give you the best chance to catch anything on the larger side. The best baitfish are Oama; they can only be found during summer months though.
South shore has a great spot that's easy to fish from and to get to--Kukui'ula Small Boat Harbor. Here you can fish off the pier or off the beach. There is a large variety of types and sizes of fish that you will catch. Some of the local favorites are Papio, Nenue, Ulua, Goat fish, Snapper, wrasse, moon fish and so many more. A favorite spot for locals is at the end of the pier because there is a reef that runs along the jetty and because of the larger drop off next to it. This attracts the smaller fish and the larger fish that come to feed.
On the northeast side, Rock Quarry Beach is a favorite spot for fishing and crabbing, due to the river mouth that opens up into the bay. The Samoan crabs that are in the river are ONO (delicious) as locals say. To catch them, you need to go to Wal-Mart or Kmart and buy crab nets, some fish scraps or squid, tie it in the middle of the net and tie a piece of fishing line or string to it, and drop them along the river shore line. It doesn't take long to catch one so check traps often and, when you do, pull it up fast before they can get out. For fishing, the river is really the best spot, you can catch some larger Papio's, some barracuda and many other kids of fish.
Hanalei is another great spot to fish where you can fish off the end of the pier or over by the river mouth opening to the right of the pier. The best way to fish either spot is with an egg bobber that lets out about 2 feet until the hook. That way you're not getting hooked on the rocks here. Also top water lures are great here for wiping.
Although we only listed a few spots, there are so many more. Get out there and explore, and always feel free to ask a local for any advice. Most the time, they are more then happy to help you figure out what to use and where to fish. Before you know it, you will be shouting Hanapa'a which, in Hawaiian, means “to make secure or fasten.” However, it is frequently used as a slang to mean “hook up” or “fish on”. Thus, throughout Hawaii, whenever a fisherman has a strike, he yells, “HANA PA’A!!!