"A fisherman is a jerk on one end of a piece of string waiting for a jerk on the other end." This old joke has more than a little truth in it.
Watching bass anglers on TV, the best of whom are some of the most innovative and skilled fishermen on the planet, reinforces the idea of jerking on the rod. However, casting a bait or lure, instead of trolling it as most marlin anglers do, requires a different method to set the hook.
The giant and rapid sweeps of the rod (basically a huge jerk) - when bass fishing takes all the slack out of the line - pulls the hook tightly and penetrates the muscle or cartilage of the fish's mouth to grab hold.
All experienced billfish anglers should be familiar with the concept of dropping back, where the angler free-spools the line for a few seconds after a marlin grabs the bait. At first, ten seconds was the magic drop-back number, but now there are a wide variety of opinions, even among the world's best skippers, on how long an angler should drop back before trying to hook the fish (notice I didn't say set the hook). Three to five seconds and eight to ten seconds are the most frequently recommended drop-back times for fish that have struck a trolled natural bait.
Both groups do well, but both also encounter a run of misses from time to time. Trying to figure out the "why" is not as important as keeping accurate logs (statistics) and nailing down the correlation between bites and catches.
Never jerk on the rod to hook any fish when trolling. This action does not add extra pressure to set the hook. Neither does gunning the boat ahead - as many skippers do - when trolling artificial lures for marlin. The motion of the boat will tighten your line, but if your reel is working correctly and has a smooth drag, the only thing that happens when you jerk the rod or run ahead is that the reel releases more line.
When trolling, all you need to do is calmly wind in the slack, with the rod pointed straight at the fish, and raise the rod when the drag starts to slip. Good reels do not increase the amount of pressure it takes to turn the spool just because the speed of a fish's run increases.
The fractional drag on the line increases as a fish runs faster, but the drag setting on the reel should remain the same regardless of velocity. (Some inferior reels' drags do change significantly with increased velocity.)
When fishing with circle hooks and natural baits, it is especially important to come tight slowly. Striking quickly with a heavy drag is a surefire formula to miss a high percentage of any kind of fish that strikes, especially billfish. Coming tight on a billfish, with its oddly shaped mouth and upper jaw, while it is facing toward the boat is guaranteed to result in a low hookup percentage on every style of hook, whether using a lure or natural bait, either dead or alive.
With J hooks, on fish you intend to release, use a shorter drop-back to try to avoid the higher mortality that results from deeply gut-hooking the fish. Some anglers still prefer J hooks and try to gut-hook prize-winning or record fish they intend to boat.
One of the major advantages of circle hooks is that true non-offset hooks almost never gut-hook a fish, and usually end up in the corner of the mouth or around the jawbone. Unfortunately, many brands of circle hooks are not the right shape or are offset, and they are more deadly than correctly shaped circle hooks.
When using large live baits and circle hooks, slowly increase the drag on the bite to about 20 percent of the line's breaking strain and wait until the fish turns away from the boat; otherwise, a belly begins to form in the line, which causes it to trail the fish.
Your intention is to set the hook by pulling the circle hook back into the corner of the jaw and avoid pulling it from the front, where the hook can pop out of the fish's open mouth. With this method, the fish is hooked at a safe initial fighting drag. Once the fish realizes that something is awry and starts to jump or make a fast run, you push the drag up.
With skilled and experienced anglers, use 40 percent of the breaking strain and only back off when a fast-moving fish gets at least 200 yards of line off the reel.
Never jerk the rod, or you will be the only jerk left on the line.