How Well do Fish Smell?

A salmon can detect the smell of it's home stream five thousand miles at sea, and follow it home to spawn 2 to 5 years later.  This amazing ability allows the salmon to detect very small concentrations of some compounds in the water. 

Members of the she salmonid family can detect L-serine amino acid in quantities as little as 1 part per 8 billion.   This phenomena will work against fisherpersons far more than for them.   If you understand & take advantage of this information, you will put more fish in your fish-box.  There are many manufacturers of fishing scent that have dedicated clients with testimonials as to the effectiveness of their product.

SIGHT,  SMELL & SOUND : In the sport fishing world there is documentation that this is mandatory if you plan on increasing your catch rate.  All of these working together will increase your catch percentages.  Any one alone can catch fish under the right conditions.  If the water is clear & shallow enough to allow light to penetrate, then SIGHT alone may be all that is needed.   However once you move to deeper, or murky water then things change dramatically.

How do you think deep sea fish find food?   It is dark down there below 100' so sight is probably out of the equation.  Sound made by the preys movement could very well be helpful.  But SMELL is also a very important item here. 

The photo below shows a Spiny Lathrope crab taken from the stomach of a 45# halibut pulled from 450' of water off Neah Bay Washington in the early summer of 2008 & is shown laying on the bottom side of the tail of the halibut that ate it. 

This crab was small, (about 2 1/2" across the body, not counting the legs) & was 100% intact, meaning it had just been picked out of the gravel on this bottom.  As you can see it is covered with a hairy type substance that would help camouflage & allow it to hide it in the gravel.  However the one thing that may have been a demise of this crab was that it was a female that was laden with eggs, a few (about 10% of which can be seen as an orange mass on her under belly.  The mass of these eggs was 10 times the amount seen in the photo.  I am sure the eggs gave off a distinct smell separate from the crab itself leading to her demise.

Spiny Lathrope crab recovered from the stomach of a halibut caught at 450'

SOUND would be from the vibrations of the lure in the water whereby the fish can zoom in as if it was using radar.  How many times have you been in your yard & a younger person drives by with their vehicle sound system set so high using a BOOM BOX that you can feel them coming?

Again relationship to fishing for halibut in deep depths one common practice is when using a spreader bar (a heavy wire in the shape of an Ell designed to separate the weight from the bait as it is descending to the bottom & to keep them from tangling) is to bounce it on the bottom occasionally.  It is known by some as "Ringing the Dinner Bell".  This creates noise of the up to a 32ounze lead weight & the spreader bar when they hit the bottom inviting the fish to investigate.

Good Smells :  This also means that a good smell, or scent can be used on a lure as an attractant to help you.  There are companies that make attractants for just this purpose.  These scents do two things; first they mask the L-serine that we all give off, but they can also contain amino acid profiles that appeal to fish to trigger feeding behavior.

Do These Scents Work?   There has been many side by side tests done and unequivocally it has proven the effectiveness of the scents and attractants.   Ask about any tournament fisherperson, experienced anglers & guides if they use scent.   There are many ways to use these attractants.   Depending on the consistency, if it is a jelly, they you smear it on the lure or flasher that is being used as an attractor.  Some of these attractants are a liquid & designed to be soaked into a fly or yarn.  There are also capsules that attach to the line that have small holes to slowly dispense the inserted scent.  There is one nylon bag sold by Silver Horde that has hatchery salmon feed pellets inside that is attached to a downrigger ball to leave a scent trail in the lure's path.  This is specifically designed by Tom Nelson of Salmon University to be more selective by attracting returning hatchery Coho salmon over wild salmon.  

Fishing guides have for years known that different egg cures work better for some species of fish than others.  This is a personal secret that they guard closely.  The egg cure they use for steelhead is different than the one they use for salmon.  This surely is smell related & not taste related.

Oil based fish attractants are said to be on the low end of the scale for effectiveness in attracting steelhead or salmon.  They will however, cause a fish to take a longer look at your offering or keep it in their mouth for a greater period of time before they spit it out.  Oil based attractants will mask human scent and most other offending odors.   Products such as Smelly Jelly;  Edge Products Hot Sauce;  Fish Formula; Mike’s Shrimp Oil, Riverside Lures Real Craw; and Cossacks Bait Products shrimp, Herring, and Salmon egg oils are considered to be primarily oil based scents.

Those attractants which include amino acids are based on evidence that combinations of amino acids can stimulate feeding in many fish species.  Amino acids come from animal proteins and all living animals have their own unique amino acid combinations, giving each a distinct taste and odor.  Few manufacturers of fish attractants use amino acids solely as the active ingredients in their recipe.  Amino acids rate high at attracting and stimulating fish from a distance.  It is thought that Berkley’s attractants are based on amino acids along with Pharmacal’s Baitmate Live and Dr. Juice’s Elixirs.

Scents such as anise oil, banana oil, and garlic are extracts from plants.  These plant bi-products do not seem to have the same fish attracting ability as amino acids, but can cause fish to be of interested as they provide an aroma steelhead are not accustomed to smelling in their normal lives.  Plant extracts are very effective in covering human odors along with others that might be present on your offering.  A few plant scents are Cossack Bait Products Anise and Garlic Gel;  Mister Twister Banana Oil;  Atlas Mike’s Glow Scent Jel and Anise Oil; and Fish Formula Sparkl Scales.

One experienced river fishing guide mentioned that at times he uses Preparation H or corn syrup as a scent attractor at times when the bite is off.

Some fish attractants are based on phermones or better classified as the elk in rut type chemical.  Phermones are chemicals that animals use to communicate with members of their own species.  Steelhead release their own phermones which are detected by the olfactory receptors of others.  Fish in general, are thought to identify members of their species through the use of this chemical.  Mating and courtship are also influenced by the chemicals presence.  Phermones decompose rapidly and it seems their main function is to alert other fish of short term danger or attraction with little or nothing to do with feeding behavior.  Dr. Juice Elixir is the only fish attractant that uses phermones.

Some lures incorporate scent directly into their soft baits like rubber worms or jig bodies.  The scent in these soft baits encourages fish to not drop the baits soon as they realize it may not be what they thought, giving you a better chance of a hookset.   Berkley has a huge selection of PowerBait for all species, including a new Inshore bait that has proved effective for halibut, and big lingcod. 

For years salmon plunker fishermen have been using oil packed tuna fish balls in a golf ball size panty hose bag attached to the mainline swivel as a attractant.  Now Brads Super Cut-Plug lure (shown below) has a hinged tail section that can accommodate scent with open slots to disperse the scent.  This hinged section is secured by a rubber band.    A great way of using this lure for salmon is to remove the inner foam & insert a sardine fillet or oil-pack tuna as a scent by packing the cavity with the attractant.  I have found that you should repack with new about every 1/2 hour. AND do not forget to remove the partly full container from the boat at the end of the day.

At times it seems these bait & lure companies are making a product to catch you & I more than the fish. 

It has been my experience that Chinook salmon seem to prefer a mix of anchovy & garlic scent.  Bass & other warm-water fish seem to prefer crawfish & anis.  Steelhead seem to prefer shrimp.

In the chart below taken from a well known fishing scent manufacturer in the Pacific NW, show what they have tested  & formulated for different species.

Clean Your Lures After Use :  One related thing here is that IF you do use scent on your lures, that it can get rancid & collect debris in your tackle box over time when not cleaned off after usage (and the sooner the better).  All dedicated fishing guides make a point of carefully cleaning it off the lure before the end of the day.  Therefore it will behoove you to make a practice to use Lemon Joy & wash off the scent before you put the lure away.  

It is important to note that some fish attractants with natural by products may become toxic after a period of time.  This not only becomes offensive to fish, but can also be hazardous to touch.  If you talk to the major scent manufacturers, most will tell you that a shelf life of 2 years is about normal if not exposed to higher heats, like being LEFT IN THE SUN.  Also many dedicated fishermen will place their scents in a refrigerator when not actually fishing, which prolongs the shelf  life.

Catcher Company’s, Smelly Jelly products seem to lead the industry with a two year shelf life without spoilage.  When using any fish attractant follow the manufacturers recommended application instructions which vary greatly depending on the product.  Keep all attractants out of extreme heat conditions, for example during the summer keep your jars of scent out of the bright sun.  This will just cook the brew to a terrible stench in which you will just be chasing the fish off.   Disposing of your old scent every year or so may seem expensive, but not if you add the cost of your boat, motor, trailer, towing vehicle, rod & reels, lures etc., then consider that this one possible thing that may help fill your fish box appears to be a rather reasonable cost in the long run.

No explanation needed

Detrimental Smells :   Like it or not, mammals, humans included, are stuck with a scent that gives off a chemical that contains the amino acid L-serine, of which fish find very offensive.   Some fisherman unfortunately have more L-serine in their system than others, this is most likely the problem with your fishing buddy who is in the dry spell all of his life.   Also this is why some people just can not seem to catch fish as they give off more L-serine than others do.   I knew twin brothers, one of which could catch fish blindfolded & one arm behind his back, while the other had to really try even to get a bite, this possibly was the situation with them.

And how many of you when tying your mono leaders or line to your terminal snap will wet the knot with your saliva to keep it from abrading when pulled tight?  If you happen to be one of those who's body puts off lots of L-serine, you have just decreased your chances of catching a fish by a considerable multiplier.

It is interesting that with the number of fisherman using fish attractants, how few are concerned with the possibility of chasing the fish away with the chemicals that repel fish.   Many common chemicals that ride to the water with the fisherman have a negative effect to Mr. Salmon.    Or it could be he or she handles such items as tobacco products, sun screens, or insect repellents, which are all taboo to most fish.  The use of any product on the market to remove the nasty scents we bring to the river are a good idea.   Berkley’s Sportsman’s Odor Remover or Baitmate’s NON SCENTS Odor Eliminator & plain Lemon Joy seem to work well. 

Insect repellent is another bad smell, the various insect lotions and sprays are not an attractant, but do act as a repellant to fish.    They can also have a detrimental effect to the finishes some of your gear or lures.  

Another thing to remember is to wash your hands after using scent before you eat lunch as some of this scent may not be good for your digestive tract.  Also if you have a dog or cat as a pet, don't pet them before you leave for a day of fishing as pets may also have odors that repels fish.

This article is not intended to blow you away with all the negative smells that we as fisherpersons can induce on our lures which can reduce our chances of catching a fish, but to make you stop & think.  OK fish have been caught for years before any of this information became available.  But in this day & age where fish seem to be scarcer & competition is greater can you take the chance?   Can you associate any of this information to some of your or your partner's experiences?  Yes I know we all have been catching fish, but are we just like a blind squirrel that finds an occasional acorn?  Or could we improve & up our catch ratio into the 10% that catch fish instead of the 90% who just fish?

If I could give one piece of advice that would guarantee more fish it would be to wash your hands with Lemon Joy dishwashing soap after going to the bathroom.  Human sweat has generous amounts of L-Serine and male human crotches have…well have lots of L-serine.   Use latex examining gloves to apply sunscreen or bug dope.  Sunscreen has metal oxides in it and fish don’t like it.   Guides who wear latex gloves do so for a reason other than to keep their hands clean.

This is my shortest fishing article, but probably one of the most important to fisherpersons, as you may save for a lifetime or go deeply in debt to purchase your dream boat only to cut your chances of catching a fish by overlooking these bad smells.

 Back to Ramblings