Sardines, both alive and dead in a packaged can, can be used for fishing bait. However, depending on how you bait your sardines, you will be more likely to catch certain fish then others. This is important to know depending on where you are fishing and which fish you are trying to catch.
Deep Sea Fishing
Sardines can be used for deep sea fishing bait, but they must be alive when they are baited, otherwise they won't be very effective. The way to properly bait a live sardine is by taking the fish in your hand and insert your hook just below the fish's spine, so that it can still swim with the hook through it and can look like a normal fish swimming through the ocean to the hungry fish you are trying to catch. However, this bait will only survive for so long with this technique, whether bigger fish are feeding on them or not, so be prepared to rebait your hook regularly.
Catfish are the notorious bottom feeders of lakes and eat incredibly stinky things. This is why packaged sardines work so well as bait for catching catfish. Chum the water to draw the catfish in by dumping a couple of cans of sardines into one area, along with the liquid they were packaged with. Then bait your hook or hooks with particularly large sardines or chunks of sardines which you can then drop into the water where the other sardines have been dumped. Allow your baited hook to sit on the bottom where the catfish will feed and unsuspectingly eat your hook.
Steelhead and Salmon Baiting
Take large sardines and filet them like you would any other fish. With these pieces of filet meat, cut them into solid chunks which can fit on the hooks of a lure which are attractive to steelhead and salmon. Make sure to insert these chunks of bait in a vertical way, so that the meat won't fall off as you reel it in through the water or a rushing stream. The smell of the meat will draw the salmon and steelhead to the lure, if the color and movement of the lure don't draw the fish already. You can also insert this meat into a plug lure, which will draw the fish by scent yet not allow them to tear it off when they strike it.
Hailing from Austin, Texas, Daniel Westlake has written under pen names for a myriad of publications all over the nation, ranging from national magazines to local papers. He now lives in Los Angeles, Calif. but regularly travels around the country and abroad, exploring and experiencing everything he can.