View Full Version : Sense of Smell: Something to think about!

06-22-2010, 10:46 PM
I have experimented with several different fly tying materials and floatants. One thing I have noticed is that the fish are extremely selective in slack water and they will pass often on a perfect fly-that mimics their current take.

So, I decided to just follow my old technique of bathing each fly in river muck/moss and I think it has helped mask some of the artificial smells of the fly. Obviously, this issue is more prevail-ant in slack or slow water. I have stopped using dyes and markers for my flies. Just wet a suspect fly and place it on a white paper town for a bit. You will be amazed at what colors bleed out. Also, I have started just using good whip finishes and forgetting the cement. My flies still hold up the same.

Here is an excerpt from a website describing the sense of smell of a trout.

The senses of taste and smell are particularly well developed in the Rainbow Trout. They are better developed than the legendary Bloodhound and about 500 times more sensitive than these senses in a human. It is believed that Rainbow Trout, steelhead and salmon (all of the scientific Order of Oncorhynchus) use taste and smell to help locate the waters of their original spawning streams.

A Rainbow Trout can smell the difference between two aquatic plants of the same species that are side by side. It can even taste the difference between two species of Chironomid and thus will have a preference for one species over another. Rainbow Trout are very sensitive to differences in ph, salinity and the differences in amino acids as found in their food sources. It is thought that the Rainbow may even have taste and smell sensors on parts of its body other than in the nostrils and mouth and that these may actually help the trout in locating its food.
I am not trying to argue one thing or another; just trying to offer up a kind tip to guys who are getting good looks, but no takes....

06-22-2010, 10:58 PM
Shawn, I find the quote very interesting. Where is the info found? I would like to see their methodology and controls.
If I get a look and no take,I turn my rod around and beat the bejabers out of the fish with the reel seat! ;)
I read of a father-and-son duo who were fishing for carp with the skinny stick. They weren't having any luck so Jr. put some garlic juice on his fly and started to catch fish. This technique is classified as using live bait in some states, so beware.

06-22-2010, 11:00 PM
I used to believe in the smell factor, but over time decided that it wasn't of huge importance. I used to never pump gas before fishing etc etc. But noticed folks I fished with who had pumped gas etc etc had the same success I was having, and the fish didn't seem to care one iota. That is a pretty limited experiment, but as the years passed I started to focus most of my efforts on presentation and location, rather then all the other stuff which can boggle the mind.

I am sure they can smell great, and sure some fish snub flies because of smell. However, I would think that tippet shine, hook shine, presentation, fly pattern, mood of the fish, and location play a larger role in success on any given day then scent.

06-22-2010, 11:10 PM
Here is the link to my citation. I should have included it in my original post.


I recommend searching "trout sense of smell" in Google and reading the various articles. One of the first things I learned below the dam from a very old fly fisherman was to 'blend-the-fly' as he called it by coating it with the river.

Please note: this tip is primarily intended for slack water and very selective/rising trout. I suggest you try a comparison and see if you can notice a difference. The Rainbows will be more selective and then the Browns and Brooks will go with about anything. Also, the primary fly I am addressing is the dry fly or the emerger. Their scent trails will be more focused and less diluted.

Forgot to mention: I am sure most bass fisherman have heard of spraying WD40 on their plugs as an enticement and other scent baits. I do not recommend the WD40 technique for environmental reasons-but, I can remember seeing it work like a charm back in the day.

06-22-2010, 11:24 PM
I think that WD-40 is fish oil based. I'll check and get back.

06-22-2010, 11:27 PM
I am sure they can smell great, and sure some fish snub flies because of smell. However, I would think that tippet shine, hook shine, presentation, fly pattern, mood of the fish, and location play a larger role in success on any given day then scent.

Jim, I did say slack water and slowing moving situations with dry flies. Personally, I think:

-most tippets are adequate enough to blend well enough in a drift. I am not well read on tippet shine; so, I need to learn more about it and investigate it on the water. (usually, I find knot size is the biggest issue with tipper or untamed memory)
-hook shine does not come in to play with my hooks:smile:.
-of course presentation is the key; that is why I mentioned they were taking what you were presenting, etc.
-pattern; see above...
-mood of fish (I mentioned; they were taking flies)

-location (I mentioned slack water and slow moving water).

06-22-2010, 11:33 PM
Shawn, I ran across lots of references on your suggested search. I'll go through them and see what is out there. Thanks!

06-23-2010, 06:48 AM
I hope no one thinks I am saying that it has nothing to do with success, because it certainly could. The bass industry has certainly shown that scent plays a huge role. I just don't know how big an impact it has on trout fishing as a whole.

I could see how fish in slack water would be a little more sensitive as they have time to inspect every aspect of a presentation.