Catching fluke might not be rocket science, but there is sound science behind it.
Sometimes it is hard for anglers to get used to the concept that even though fluke have the same five senses that we humans do, the relative importance and ability of the individual senses is quite different than ours and they live in a marine environment quite unlike the airborne world we live in.
The olfactory sense, the sense of smell, is one that is commonly neglected and misunderstood but is an important, if not the most important sense that anglers need to pay attention to entice fluke to get on our lines.
The sense of olfaction, the ability to smell chemicals, is a primitive sense present in even very primitive creatures. The visual clues that come from eyesight must be interpreted by the brain for a creature to act upon that information. On the other hand the sense of smell is so primitive that a creature, like a human or a fish, reacts to that stimulus without even thinking about it.
The chemical sense of smell in a fish can cause it to track a bait, attack a bait, and hang onto a bait without the fish contemplating its action. This primitive reactive behavior can be utilized by anglers to their advantage to put a better catch together.
Science of Fish Olfaction
Olfaction is vital in bait procurement for most fish including the fluke we seek to catch. Smells that fish pick up in their environment trigger them to go on the feed and help them to locate bait sources. In fact, many fluke end up feeding on spots like wrecks and artificial reefs, using the scent trails emanating from the intense bait laden structures to guide them to that area during their migratory phase.
Fluke are able to detect odorous compounds dissolved in water in the range of parts per billion to parts per trillion, an ability far surpassing the capability of humans and many other land dwelling animals. Fluke likely can smell chemicals that humans are unable to detect, and detect them at low levels that would be unrecognized by us. With visibility in water far less than in an air world, other senses assume greater importance. In humans more than 70 percent of our brain is involved in visual interpretation. In a visually limited marine environment, other senses like olfaction take on an important role.
Summer flounder have an olfactory apparatus different in certain important ways that enable them to have such a well-developed sense of smell. Humans and many land animals have one opening on either side of our face for incoming scents, the posterior opening being the back of our throat. Most fish species like fluke have two openings for each one of their nostrils; the one further forward for incoming water, the other for exiting water. They are able to pump water through their nostrils in a number of ways including the beating of the cilia that line the internal nares, the pumping action of the accessory sacs, the movement of their jaw bone during respiration, facing into a current, and by swimming forward.
Fluke use their incredible sense of smell to help them find our baits and determine whether they are appropriate food sources. The better an angler mimics the natural bait smells, the more successful the fishing venture is likely to be. Although fluke are occasionally caught with no bait at all, few anglers venture out on a fluke fishing trip without bait of one sort or another.
Natural Bait Selections
Before the invention of artificially scented baits, many fluke were and still are caught on store bought natural baits or bait secured while out fishing. Many baits fall in this category such as squid and fish strips made from sea robins, bluefish or others. Other baits like spearing and sardines may be working more because of the scent they produce than from their physical appearance.
Some baits work extremely well even though they are not part of the normal diet of fluke. Baits such as strips of tuna, false albacore, bonito and herring will entice fluke to feed because the scent they produce is so intense and imitates other bait sources that fluke feed upon. In fact, the chemical sense is so strong from these types of baits, they work extremely well, often outperforming less pungent bait sources.
Keep in mind that the compounding effect on the ability of a bait to produce scent by stripping out that bait. I remember one angler bringing onboard some live mullet that produced poorly until some of the deceased baits were stripped out and used that way. A whole bait only produces odors from its surface mucous and pheromones, but once a bait is stripped, all of the thousands of internal chemicals are released into the water column and produce a much better feeding stimulatory effect than the same bait fished live.
It is important that natural baits are kept as fresh as possible as rancid bait will catch unwanted creatures but not usually the fluke we are seeking to catch. If you purchase bait, try to get it from a tackle shop known for keeping their bait in good condition. Squid purchased that looks black or smells badly will not produce as well compared to a nice translucent looking specimen that honestly would be fit for human consumption.
It is important when you secure your own bait on the boat that you keep that bait in good condition. For example if you catch some sea robins and want to use them for bait, make sure you cut them into strips while they are freshly caught. Once stripped, the baits should be kept cool, moist and out of the sun. Storing them with a cool moist rag on top will keep them in good shape for a half an hour or so if the rag is kept moist and cool. Storing them in this manner with the skin side up will prevent the water in the rag from causing the bait strips to swell and not undulate well when deployed.
We, as humans, won’t be able to smell the difference between a bait just prepared and one that has been sitting on the bait board for a half an hour. To a fish though, with their heightened olfactory sense, the bait smell can lose its appeal to make a fluke strike that offering. Baits become rancid exponentially meaning in twice the time, the rancidity level has increased fourfold. It is important to only strip out as many baits as you can use in short order. If you like to prepare a lot of baits ahead of time, take the majority of them and keep them in a bag on ice in your cooler.
Freshen It Up
Another factor to remember is that the bait you are using is losing its best scent characteristics in the same exponential way. The freshest baits are the ones that are producing the most scent you want to be releasing into the water column. Sometimes, one reason one angler on a boat keeps catching and others are not is because that angler is changing his baits more often as he reels in his fish and rebaits his rig.
Importance must be placed on not loading our baits with any extraneous chemicals. Baits stored in containers used for other purposes or baits placed on hooks with hands contaminated with sun tan lotion or other chemicals can really alter a bait’s effectiveness.
Keep in mind too, that our human decision of what is a good scent may differ entirely from what is enticing to a fish. Another charter I remember had brought some foul smelling gray looking herring that ended up being the top producing bait. I recall another day anchored up fishing with dried up stinky clams for sea bass where we ended up having an outstanding day catching fluke.
The longer that bait is deployed in the water the quicker it is becoming rancid. Our baits stay the best in very cool environments but once deployed in the warm waters where we are fishing, the bait is quickly changing its scent characteristics as the bait heats up from the ambient water temperature. Baits fished too long can lose their effectiveness not only because they are losing their scenting abilities but also because they are becoming rancid.
One natural bait that works that may seem surprising is the use of strips of dogfish, both smooth and spiny (what are often just referred to as sand sharks). These tough baits withstand the attacks of many creatures and can work very well particularly when fishing in bays and inland waterways. One would think that the scent chemicals produced by a predator of particularly young fluke would be counterproductive as a bait. Indeed, though, the stripping effect here too produces excitatory chemicals from the internal flesh of that creature that exceed those of any fear generating response by the feeding fluke.
Fake ‘em Out
Many anglers have taken to fishing with baits manufactured and loaded with what are called semiochemicals. These substances are stimulating chemicals that entice a fluke to bite, in some cases, enticing a fish to strike when it may have not been in a high feeding mode. Products such as Gulp! or Fishbites use these types of formulations to soak into their artificial baits.
Gulp! has been made with water, rather than oil-based resins, such that it will best sponge up the chemical to be released. When fished, these baits will release these special compounds in a very enticing way. It is important to keep in mind, though, that these sponge-like baits are losing their effectiveness the longer they are fished. Astute anglers soak their Gulp! baits back in their containers while the boat is moving for a new drift. Periodically changing these baits is also wise for the same reason, placing old baits back to the tub to be recharged.
Some very good anglers have learned that loading their rigs with multiple bait sources can produce the best results. Combinations of artificial and natural baits on the same hook can reduce the visual appeal of the offering, but the overwhelming scent stimulatory effect can overcome any loss of visual cues that rig provides. I’ve seen anglers have some very exceptional results loading the rig with three or more different baits, sometimes so loaded the hook is barely protruding.
It is common, for example, for anglers to put a piece of Gulp!, spearing and fish strip on the same rig when fluke fishing. Anglers will experiment in this way with different combinations of baits to find what is working best on that day.
Once the feeding preference of the fluke is discovered all anglers on board can switch to that bait or combinations of bait.
Capt. Harvey Yenkinson runs Vetcraft Sportfishing charters out of Bree-Zee-Lee Yacht Basin in Cape May, NJ. He received his Bachelor of Science Degree in Animal Science from the University of Maryland in 1971 and Veterinariae Medicinae Doctoris from the University of Pennsylvania in 1975.
FAST FACTS FROM NOAA FISHERIES
Summer flounder – aka fluke or Hirame – are found in the Atlantic Ocean from Nova Scotia to the east coast of Florida, most commonly in U.S. waters in the Mid-Atlantic region from Cape Cod, MA to Cape Fear, NC.