Fish attractants are an important aspect of salmon and halibut fishing. The Bait Set-up Triangle rigging means adding fish attractants to salmon and halibut gear. It all makes more sense when understanding basic fish physiology. This month’s blog will look at odor-detection systems in fish and how to rig baits to take advantage of food-seeking behaviors. Last month’s blog revealed three fundamental elements for bite triggering—sight, smell, and sound.
Sensory Systems
Humans use sensory perception to make food choices. The sizzle of a steak on the grill whets our appetite in anticipation of a favorite meal—that’s sound. We get excited by an afternoon baking aroma, knowing apple pie for dessert is served after our steak dinner—that’s smell. And when we pull the rack of salmon out of the smoker, recognizing the lovely appearance of a perfectly done piece of coho—that’s sight. As soon as it cools, we pop a piece into our mouth.
The human senses of sight, smell, and sound affect our food choices. Fish are no different—they also use sight, smell, and sound to make their food choices. Therefore, using baits that activate a full range of a salmon or halibut’s sense of sight, smell, and sound is fundamental to drawing out a fish’s feeding behaviors.
If you choose to omit one element from your bait set-up, you should know why. For example, Alaska fishing regulations prohibit the use of “bait” in some of our waters. Alaska defines bait as any substance applied to fishing gear to attract fish by scent. Therefore you shouldn’t add scents to lures if regulations prohibit the practice in your area.
Odor Detection
Now, let’s take a few moments to look at a fish’s olfactory or odor-detection systems. But first, a disclaimer, we simplify our interpretation of fish physiology through a fisherman’s lens of science. Simple is good. A salmon or halibut’s sense of smell breaks down into four main parts, an odor key, the epithelium keyhole, the recognition wiring, and the recognition center.
Science tells us that odor keys are, by and large, microscopic bits of fish. One odor key example for illustration purposes, which many of us have heard about, is amino acids. Amino acids are the building blocks of proteins, and proteins make up fish body parts like muscles. These odor keys are at the molecular level, so tiny they are not seen by the human eye in the water column.
Odor keys are freed from baitfish and suspended in the water column through normal fish activities. Salmon or halibut pick up these odor keys as they swim or wait in ambush. When odor key concentration thresholds are met, a salmon or halibut’s odor-sensing epithelium keyhole registers these compounds as food sources.
Recognition Wiring
Scientists believe odor-key molecules match at the epithelium keyhole momentarily. When these matches are made, a recognition signal is generated. The concept is similar to your cell phone’s fingerprint key. When the right fingerprint momentarily covers the screen, the correct match generates a signal to open your phone.
Once the recognition is achieved, a signal is generated. It travels through the recognition wiring and registers in the recognition center. Fish have specialized odor-sensing recognition centers called Olfactory Bulbs that detect underwater odors. Humans do not have Olfactory Bulbs.
When the recognition center is excited by incoming messages of a tasty morsel, it sends a signal down the brain communication line. Then, other parts of the fish’s brain tell the body to get active and start looking for food. In other words, the fish begins looking for the odor source, thinking its dinner bell has rung. If you rigged right, that is your bait.
An Excellent Sniffer
Now that we know how odor cues lead to food-searching behavior, we should quickly look at the fish’s ability to detect odors. One experiment used by scientists to determine a fish’s sensitivity to odors is dripping food-source solutions in tiny amounts into a tank of hungry fish. Then, scientists increase the concentrations until the fish demonstrate food-seeking behaviors.
They found that fish begin food-seeking activity when odor keys are in a concentration range of one odor molecule in 1,000,000 to 1,000,000,000 water molecules. Granted this is a large range but illustrates the incredible sense of smell possessed by fish.
Visualize the Numbers
To help us visualize these numbers, if an amino acid molecule were the size of a pinhead, then a fish could smell that one pinhead suspended in the bottom ¾” of a gallon milk jug in the one part per million end. That’s pretty impressive. Another experiment shows salmon can smell at one part per ten million. Using our milk-jug illustration, this would be equivalent to one pinhead-sized odor key in an 8½” gallon milk jug. That’s much more impressive.
Finally, to illustrate the one part per billion, one pinhead-sized amino acid molecule is found in an 812.5” stack of milk cartons. That is unbelievable! Incidentally, halibut are thought to detect odors in the one part per billion range, but I’ve yet to find research that verifies this number.
A Lot of Water To Cover
A tablespoon holds approximately one million water molecules. Ten million water molecules are about ⅔ cup of water. And one billion water molecules are slightly less than 4 gallons of water. Of course, we all know that there are many tablespoons, cups, and gallons of water in the lakes, rivers, and ocean bays we fish.
Although salmon and halibut have very sensitive odor-detection systems, the simple truth is we need to cover a lot of water to activate their odor-detection systems. So, the more scent you’re sending out from your bait, the better your chances of turning on their food-seeking behaviors.
Solution – Scent Striker
The solution to more odor keys in the water surrounding your bait? Scent Striker! Scent Striker fibers hold lots of fish attractant, and its hollow center means you slide it on your leader where you most want odor keys—by your hooks.
To illustrate, we’ve added a picture of our typical hoochie rigging to show a couple of Original Scent Strikers between the terminal and second hook. Again, we recommend odor keys right where it counts, at the hook end. To finish tying this rig, four 8 mm spacer beads are installed in front of the forward hook, filling the squid head and moving the skirt so that the terminal hook is exposed.
The squid slides on over the bead, the leader is cut to length, and a swivel is tied on the leader’s end. Out on the water, the beads and squid are moved up the leader away from the forward hook. The Scent Strikers are dipped into a puddle of DBS-Striker Formula, working the scent deep into the fibers through a bit of stirring, and the rig is ready to go overboard. Turbocharging a hoochie rig or any other salmon or halibut rig is easy using Scent Striker.
A Word of Caution
One fascinating scientific find by one researcher is that a “finger wash” solution dripped into a tank of hungry fish caused the fish to distance themselves from the odor. For this experiment, the finger wash was the researcher’s finger swirled around in a liter beaker of distilled water. As a result, I now use nitrile gloves when handling my gear and baits.