It is interesting that many people go fishing and come home with nothing, and yet are not discouraged from doing so again. It is difficult to say definitively why fishermen fish, but it is with some confidence that I say that the most effective means of fishing also require the most effort on the part of the angler. Fishing requires no small amount of attention or effort to do effectively. Perhaps this is why people don't catch fish? I am Mark Santos, and I fished Little Jim over and over again until I learned how to catch fish there, even during those times when everyone else went home empty-handed.
Little Jim bridge is a bridge, and it is accompanied by a 10-12' channel and a fishing pier. It also has lots of lights, and is surrounded by the shallow grass flats of the Indian River. I fish at the base of the bridge, and though there is much structure located directly under the bridge, I prefer the north side of the eastern base of the bridge. Aside from a distinct shadow line, which is important for predators and prey alike, I can fish feet of fast water or inches of slow water, or some structure or all of it, simply by walking a few yards west or east, respectively. As a habit, I fish the rocks on the northeastern side aggressively. This is, by the way, my secret to catching fish here on just about every trip.
The fish almost always hold near structure, or places where the current changes dramatically (e.g. channel edges). Some fish hold right next to the wall or behind and in front of pilings or rocks, etc. However, the question then becomes: where in the water column are the fish holding? Since the area around Little Jim is relatively shallow, with the exception of the channel, it is fairly easy to answer this question. In practical terms, I use ¼ ounce jigs, and plugs that dive up to 4-5'. But this isn't always effective, especially when the water level is particularly high, or particularly low. The water level can be low to the point that the majority of fish do not hold to the structure closer to shore, and makes long casts to open water necessary, while a high water level can present its own set of problems (e.g. makes my plug far less effective since it's not bumping into anything or running near the bottom). In practical terms, I bring a couple of ½ ounce jigs just in case I have to fish the faster, deeper water.
The type of retrieve to use is a question that is difficult to answer. A whip or fast retrieve has at times caught fish when nothing else worked. Jigging can also be effective, but the retrieve I try first is a slow, steady one. To elaborate, cast uptide and reel just fast enough to keep the slack out of the line, bouncing off bottom or structure all the way. I use this retrieve with both plugs and jigs, and it has worked the best. It's not for the impatient though, and you have to be confident that it works to make it work. I believe this retrieve works because this is how fish in the area catch their food, in this case, shrimp and small baitfish that cannot swim against the tide but are washed along with it.
Note that with jigs I will increase my retrieve speed in order to keep from hanging up, staying just above the structure, but I will still reel as slowly as feasible. Additionally, reeling in slack line presents problems at the reel, and consequently requires constant attention.
An hour after dusk to the first hour of dawn is productive, with action peaking a little while after most fishermen have gone home (and noise level, and fishing pressure, substantially reduced). I used to fish 2-4am and enjoyed great fishing. An hour after dusk has lately been excellent, and around midnight has been known to be a 'feeding time.' In short, low light conditions are important for the shallow waters about Little Jim. Second in importance is the stage of the tide. Slack tide is not as productive as, well, not slack tide, or faster current. Current changes almost always are a 'dinner bell' for fish.
Note that I fish for snook, and an hour before dusk is a good time to target other fish, particularly bottom fish like snapper.
I have a lot of faith in DOA lures. They are expensive, but they are the lures for fishing Florida. They're certainly worth the money, but, if I was hard up on money, I'd buy some ¼ ounce red saltwater jig heads and pair them with some 4" chartreuse shrimp tail jig bodies. In general, however, any ¼ ounce jig, rigged with a saltwater hook, in yellow, white, or chartreuse will produce.
However, I typically start out with plugs first, to probe the water, and also to see if the fish want a more subtle presentation (e.g. a ¼ ounce jig). In my opinion, the Berkley Frenzy Saltwater Diving Minnow is an almost entirely idiot proof way to catch fish. It may cost about six bucks and doesn't look as pretty as, say, my Yo-Zuri Tobimaru, but once you compare this plug's performance to other floating diving minnows, you might buy every one you can find, stocking up 'just in case.' Personally, I bought six of these on clearance several months ago, and I have lost all but one, and this last one is like an heirloom to me. I had the first one for quite a while, and it went through at least three sets of treble hooks before I lost it, including a set of nickel teflons. When I lose this last one, its place will be taken up by the aforementioned Yo-Zuri Tobimaru. I consider it a downgrade, but... Bottom line: I treat these plugs better than my mother.
Shallow water and people scare fish away from the pilings closest to the bridge bases, so the only way to fish Little Jim effectively other than my method is to fish from atop the bridge. The most successful fishermen will have lures or live bait and actively manipulate them under the lights above the channel and shadow lines using thirty pound tackle or heavier. The channel itself is very fishy, but boat traffic can present problems. In my opinion, fishing from atop the bridge is much more difficult than fishing the shallow rocky water I'm so fond of. For the sake of completeness, mangroves near the bridge also hold fish, but are slightly less accessible.