How Marlin and Sailfish REALLY Feed!

…And, why you need to “Drop Back” to consistently hook Billfish when using live or dead natural bait.

The family of “true” Billfish includes all the species called Marlin, all the Sailfish (which are split into the Atlantic and Pacific species with the Pacific Sailfish also being found in the Indian Ocean), several species of Spearfish and the Swordfish, which is sometimes referred to as Broadbill Swordfish.

All of these fish are members of the teleost group, which are known as “Boney” fishes and are closely related. The true billfish, with the sole exception of the Swordfish, vary only slightly in how the different species capture and kill their prey. I am about to explain why the common myth that all billfish use their bill as a sword, or a club, to kill their prey is not correct!

The Swordfish is easily distinguished from the other species of billed boney fish by their flattened, sharply edged, upper jaw or “Sword”. They frequently use it much as warriors’ metal swords were used in years gone by, to SLASH at their enemies, or in the swordfish’s case, at their prey.

Anyone who has ever baited a swordfish by slowly trolling a bait in front of one and managed to get a bite, will never forget the sight and the sound of the sword- like upper jaw slicing through the water when the fish attacks the slow moving bait!

As a young deck hand, fishing out of Martha’s Vineyard, I was usually standing high up in the boats’ tower holding the fishing line very lightly between my thumb and forefinger.  I’d be slowly making adjustments in the length of line we had to let out into the water to keep our bait close to, and in front of, the slowly moving fish, where he could not help but see the bait!

When the strike came, if it ever came, it was SAVAGE! The bill slicing through the water HISSED, loudly enough for me to hear it even in my elevated position up in the tower! Sometimes the line was snatched so savagely out of my fingers by the speed of the slashing bill that I got a blister from the line. There was no need for a sailfish type of free spool drop back! The skipper would back up for a few yards after getting a strike, then move the boat slowly ahead until the line came tight with the reel set at our strike drag and we had him on!

From the fish’s perspective, it had killed its prey and then swallowed it. When the line tightened, the fish was hooked, often deeply!

In more recent years, both commercial fishermen and sports anglers, reacting to techniques developed by Cuban commercial fishermen, have developed  “deep dropping” techniques which changed catching a sword fish from the most unlikely event for a recreational angler, to the most common, except for the sailfish which is still the star billfish, especially for Florida waters, due in large part to their large populations and year round access for anglers with small boats.

The Sawfish which is called a “Saw Shark” in Australia, is really a member of the shark family and is not a boney telost fish. It is quite different from all the other billfish but also slashes like the boney Swordfish. This strange looking shark has a long, horizontal sword which is filled with wicked looking and very dangerous external teeth that raise havoc when swung through the schools of mullet in the shallow water in which saw fish thrive. Saw Fish can kill, or cripple, dozens of the small bait fish in a very short time! They then feed on the dead and dying at their leisure!  Saw fish are feared by commercial fishermen, in whose nets they get hopelessly tangled, but remain capable of inflicting serious damage to both boats and the men in them!  They are not considered to be a sport, or game fish!

The Billfish that recreational anglers seek around the globe all have very similar ways of catching, killing and then swallowing the prey on which they feed. It is quite different from the SLASHING attack of a Broadbill Swordfish! These Billfish all have rounded, tapering, boney jaws, with very strong muscles that can make the upper and lower jaws clamp tightly enough together to easily kill most of their prey species if the jaws close on their vital organs.

Both upper and lower jaws have a multitude of very tiny, external teeth, called “denticles” which gives them a rasp like surface on both upper and lower jaws.  This helps them to hold  on to their prey when they succeed in grabbing it with their jaws.

Sailfish and marlin only rarely slash at a single food item, such as a single fish, squid or eel with the sideways movements of Saw Fish and Swordfish.  However, there is one fairly common exception to this no “slash rule”. It is the tendency of both marlin (especially the smaller white and striped marlin) and sailfish to slash their bills wildly into any of the compact schools of very small bait fish that anglers and crews often refer to as bait balls or “Meat Balls.” A large pack of sail fish will often work together in order to round up a school of hundreds or even tens of thousands of their prey, forcing them into a tightly packed school. They can then take turns attacking the school of bait, rapidly killing or wounding hundreds or thousands of the small fish by slashing into the dense school with their upper jaws, that we call the bill!  When this occurs, multiple dead and dying bait fish can then be easily taken directly into the billfish’s mouth and rapidly swallowed in an orgy of feeding. It takes very little skill to feed a dead natural bait to a billfish under these conditions.

Finding Billfish feeding on a meat ball is an anglers dream come true! By free spooling a dead natural bait, or a badly wounded live bait, into a meat ball and allowing it to sink, an angler can  create an easy meal that is hard for a hungry fish to resist!  By releasing the reel’s drag and pulling out several feet, or a few yards/meters of line, before getting a strike or a pickup, it is easy to detect when a fish picks up the bait and begins to move on to get another meal. Engaging the reel and winding in the slack line until it comes tight is all it takes to have a good hook up! If the prey is small enough, and the meat ball is dense enough, both sailfish and marlin will rush into the massed school with their mouths wide open and suck one or more small minnows into their mouth and throat along with an excess of water, which is then forced back out through the gill rakes and the food is swallowed. A small live or dead bait will usually get a bite in this situation as well.

So, When Do You Need to do a serious Drop back? And How Do You do it?

A single marlin of any species or a sailfish, usually attacks any single, lone prey from underneath and behind or from off to one side. Rarely does a bait rush toward a large predator!

The prey invariably tries to swim away, as fast as it is capable of moving, often making twists and turns in many directions as it tries to escape. Small tuna will often exhibit this behavior when chased by a marlin but even a tuna cannot beat the speed and stamina of the larger and faster billfish! A marlin can easily grab (with its powerful jaws), kill and swallow a tuna weighing ten percent or more of the billfish’s body weight.  I once used a live tuna, weighing well over 30 pounds, for bait and caught, tagged and released a modest sized blue marlin.

I have seen small, half digested, billfish in the stomachs of marlin and can only wonder how the larger fish managed to get them down!

If marlin fed by hitting a fish, or a lure with its bill, then very few fish that DID get caught by anglers trolling lures, would be those that were caught by getting foul hooked outside the mouth. The majority of the marlin I catch on lures are hooked inside the mouth, and they have been given little or no drop back.

A Typical Billfish Strike

A typical Bill fish strike, on a lone natural bait, often goes like this. The big predator swims rapidly toward the prey or bait and then, when it gets close enough, lunges upward and forward, trying to capture the bait in its mouth, between its jaws. A marlin chasing a small tuna or a sailfish eating a ballyhoo can catch one, crush it and swallow it in mere seconds. It then looks for another snack!  However, if the prey dodges successfully, the predator must try again, once or several times! Sometimes the prey actually escapes, and lives long enough to breed and make more prey for other billfish to feed on.

How Marlin Swim

Marlin and sailfish use what the scientists call a “sinusoidal swimming motion.” It is called this because of its similarity to the shape of a sine wave, like one displayed on a computer screen of an electric current. As it swims in this manner trying to feed, its bill must be above the water’s surface for the fish to capture a prey or your bait, swimming on or near the surface! It can now easily appear to an angler or deckhand watching from the cockpit, that the fish is trying to beat its prey to death with its bill!

However, this is not what actually happens, since this would be a very ineffective way for a marlin or sailfish to make a meal out of a single, fast moving, flying fish, mackerel, or tuna. What a billfish is most often attempting to do is to first, swim rapidly toward any lone morsel of prey. It then LUNGES both forward and upward in an attempt to grab its intended meal between its bottom and upper jaw!

Billfish have good binocular vision, which means they can see very well with both eyes. As a result, they can detect both the direction and the speed of the prey that they are chasing, but only IF it can be seen simultaneously by both eyes! (Imagine a one-eyed batter trying to hit a fast curving baseball!  This would be almost impossible, but it can be done consistently by a batter with two good “binocular” eyes.)

The fish’s bill, as it lunges over the prey may obscure the view of one eye taking away its binocular capability. In theory, this should be a handicap, as the fish can now no longer see and react to changes in speed or distance.  Nature still does not reward changes that are detrimental to survival and or reproduction!  After thinking about it for a long time, I came to believe that ,at this stage, the bill becomes what I have now come think of as a “food guide. The bill now helps ROLL the prey into contact with the bottom jaw. The two jaws can now quickly crush the life out of what has now become a dead and tasty tidbit of food!

 Head Shakes Finish Off Wounded Prey

Very Commonly, a marlin or sailfish that has captured a prey but has not yet killed it, will shake its head rapidly and violently allowing it to break the prey’s spine, thus depriving its captured prey of any chance for an escape!  Once again, a fast, agile fish is now a snack! This behavior is commonly seen when playing with a dog and “fighting” with it over a toy! When your puppy’s earliest ancestor caught a rat, if it shook its head and broke the rat’s spine, he had a meal, instead of getting viciously bitten by its intended dinner!

If the sailfish’s captured ballyhoo is not killed or held tightly enough and it escapes, it must be caught again with a big waste of precious energy being the cost!  If the billfish does not get a good enough grip on its prey’s vital organs to kill it immediately, when the prey struggles, instinct tells the predator NOT to let go!! Nature rewards conservation of energy by allowing the saved energy to be used to create more eggs and sperm which in turn allows more baby sailfish to be created. 

Now, imagine a marlin or sail getting a good grip on only the bony tail of a small tuna. No matter how hard the predator squeezed the bony tail it could not kill the fish! If the predator opened its mouth the prey would get away and would have to be caught all over again! Only when the bait fish quits struggling, often due to a broken spine from the powerful head shakes of its captor, would the bigger fish release the grip on the tail and then easily swallow the prey.

Releasing the drag from a reel and free spooling a bait with a hook in, or on it, fools the predator into releasing its prey and it immediately swallows the carcass, providing an angler a good hook up!  It is the most common tactic in bill fishing but takes skills which need to be learned.

I have watched exactly this behavior, including from under water, many times. On a trip chasing a lady’s world record sailfish, I jumped into the water several times with a face mask on when we had raised a fish of less than record size but not too large for us to bring it up to the boat rather easily.  This is how I first got to watch and see from up close how feeding billfish really behaved!  If the deck hand free spooled a hookless bait immediately, the fish ate the bait, swallowed it almost instantly and started looking for something else to eat!   Sometimes we could pull the mostly intact bait back out of the sailfish’s stomach and sometimes they would eat it again but they only swallowed it If we free spooled very quickly on the second attempt! This behavior is not uncommon in normal every day fishing situations!

If I told the mate, “Hey Scott, do NOT let this one have it” there was a very different pattern of behavior! If Scott pulled hard and with a lot of drag on a heavy line, the fish that had grabbed a bait continued to hold it, kept on swimming slowly down, vigorously shaking its head and it never did let go and try to take the bait down into its stomach. Only when the “prey“ stopped struggling would the billfish open its mouth widely and swallow the bait.  We deliberately broke line a couple of times, but never by free spooling, just to see what would happen.  In this case, the fish would very quickly swallow the bait when the line broke and would swim off trailing a length of monofilament nylon. This is surely not the best thing for a fish we intended to release!

Hooking a Bill Fish Without Any Fear of a Backlash!!

As a charter boat mate, captain and Head Instructor for Marlin University, I had numerous novice anglers come aboard wanting to catch their first Sailfish or Marlin. We were usually fishing under IGFA rules, which state that the angler must hook his own fish unaided!  No one else could even TOUCH the rod, reel or line once the fish struck the bait or lure. Several of our student anglers told me that their main desire was to learn how to drop back to a Sailfish! I always asked them if they if they fished at home and if so for what?  In addition, I asked what kind of rod and reel did they use? If they used a plug rod, I told them that they already knew how to drop back!  Anyone who can throw a lure to a bass more than a couple of rod lengths away or can cast a bait and heavy sinker into the ocean, past the surf break, will have no trouble “Dropping Back” to billfish!! If they had never used a plug rod and level wind reel, I gave them a few quick few quick lessons with one of our outfits on dropping back before we started trolling. I also told them to go home and practice CASTING with a non-Spinning Reel.

Many anglers and crew members put way too much pride on their skills at hooking billfish!  It is not hard to learn to use your thumb to control the release of line from a conventional reel. Spinning reels make it easy to give a fish a tension free drop back. However, these same reels are inferior tools for fighting big fish, when compared to lever drag, star drag and conventional reels, because they put twist into the line whenever a fish takes line out against the reel’s drag.

NOW GO SOMEWHERE, WHERE the bill fish are THICK and HAVE FUN!! Good Luck! — Peter B