SCIENTISTS REVEAL HOT COLORS FOR TUNA LURES!!!

[jurelometer]

I was sidetracking PJ's celebration of painting eddie bombs for the fun of it (https://alantani.com/index.php/topic,38596.0.html), so I  decided to move the science-based topic to a fresh thread.

So which colors are going to make a difference to tuna according to the best available science?

Uhh, blue and...

That's it.  Blue is the  only color that they can see.  They are colorblind.  OK- one study found a  minimal number of violet receptors in yellowfin eyes, but not enough to change the assertion that tuna are effectively colorblind.

On adult yellowfin tuna, the rod cells and cone cells both respond in a narrow blue range with a peak wavelength around 485 nm.  That is a makerel-ish kind of blue with a tinge of green in it Other species of tuna are in the same ballpark.  To get an idea -take a look at this chart:



Here's a quote:

Although tunas have two classes of cones (see review in Fritsches et al., 2000), electrophysiological measurements indicate only a single luminosity-type spectral sensitivity curve at photopic levels, peaking in the blue-green around 490 nm. Thus they are considered to be cone monochromats and, therefore, color blind.

Source: https://www.researchgate.net/publication/248924262_Developmental_Changes_in_the_Visual_Pigments_of_the_Yellowfin_Tuna_Thunnus_Albacares#read

Lots of other good stuff in this paper - including finding some cone cells that picked up violets (peaking around 425 nm) .  These were concentrated on the top front of the eye (most important for visual feeding), so they probably serve a purpose, but are scarce enough to not change the conclusion that yellowfin are also colorblind.  From the same paper:

The function of the violet cones is obscure. Nevertheless, they are associated with the major optical axis – i.e. directed toward the sea surface. The presence of a violet absorbing visual pigment does not negate the earlier suggestions that tunas are color blind, but certainly tuna should no longer be considered isochromats

Lots of other papers out there.  All the same conclusion. They figure this out by examining chemicals (opsins) in the receptors (rod and cone cells) and determine which wavelengths of light cause them to generate an electrical impulse.   They also do some more gruesome experiments by flashing different light wavelength on freshly extracted eyeballs and checking for electrical current coming out toward the ganglia (nerve bundles that collect signals). 

Not all species of fish are colorblind.  But you might be surprised how common colorblindness is among the glamour species of saltwater fishing. Especially once you get past the shallows.

This has been known for decades, and seems to be pretty settled science.  But the fishing community is highly resistant. 

Now here is the tricky part:  Pretty much all the colors we recognize as humans are not a reflection of a single wavelength, but a combination of wavelengths.  That hot pink lure that seems to be working probably has a big chunk of blue of the right frequency in it.   But that same paint job would be seen more by the tuna if it had more of the blue, and less of the red that the tuna can't see.
 
And for some reason we are fixated on color when there is much more important (and interesting!) aspects of the visual systems of fishes.  In the meantime:

stay tuned for "SCIENTISTS REVEAL HOT COLORS FOR MARLIN LURES!!!" 

-J (AKA- Mr Buzzkill)

[Maxed Out]

 Any info on which color is best for albacore ? ...and is there a difference in their visual spectrum at night ?

[jurelometer]

Albacore should be the same as the rest of the tuna - and only see blue. I think that there are two color possibilities for daytime near surface:  blue so that the fish can see it with the higher acuity blue cone cells, or anything but blue, so that the lure stands out from the blue water around it.   There is some stuff written about how visual systems enhance edge imaging - but don't remember how they figured it out and if it applies to fish. 

BTW My favorite (daytime) tuna flies have lots of black and flash on them. but I am an outlier.

Some fish species physically move the rod cells (more sensitive, less accurate) outward for the night, but in the case of tuna species, it won't matter because the  both rod and cone cells peak at the same wavelegth (blue).

But mostly it is too dark at night underwater.  Just some biolumincense and a tiny bit of difused light.  Which meands everything is backlit and color shouldn't matter.

Back to daytime: If I was looking for something new and exciting for albacore, it might be very small black and chrome irons for those days when they are keying on small stuff but won't bite bait or the usual lures.  But take this with a grain of salt -it has been decades since I have chased albacore


-J

[Keta]

I still like black or black and purple but most of my iron has a lot of blue on them.

[MarkT]

I've always thought with both surface and yo-yo iron, it's the contrast, not the color. Scrambled egg and mint/white have a softer contrast and blue/white and black/white (good for 'cuda) have a stronger contrast. Tuna jigs at night? Color isn't important 300' down at 2am... they aren't seeing any colors! The color is to catch fishermen at the store, not fish in the ocean!

[Keta]

Yup.

[jurelometer]

You guys are killing me

Remember that black/dark is the absence of receptors firing off.  So what might be a bright yellow scrambled egg jig to us humans could be the same as black to a tuna with no ability to see yellow. Same with red. No matching receptors equals the same as black.

But to pick on myself for a bit:  While the blue receptors on tuna species peak at 490 nm, they get decent but weaker reception from about 460 to 510 which means mostly blues but leaking well into the greens. 

Since weaker reception could either be from a less than ideal wavelength or simply less brightness (AKA amplitude- light waves have both length and height),  I don't expect that tuna can tell blue from green the way we can. They would need both blue and green receptors to tell the difference.  Such is the life of a monochromat... 

You can play with the wave length to display color with this tool:
https://405nm.com/wavelength-to-color/

-J

[Ron Jones]

I throw any surface iron as long as it is a blue and white Salas 7x, or the same color smaller iron for albacore. The iron I have had the best albacore luck with is the blue and white Salas 6x yo-yo. Completely factual, I in no way have caught enough to call it a sample that meets statistical significance, but I do appreciate that I have science in my corner. I am still convinced that disruption of background energy is as significant as anything else. It works for me for decades, don't see why it doesn't work for fish.

At the end of the day, smashed lead with a hook in the right place.
The Man

[oc1]

Since everything is just varying shades of blue, it seems that the pattern would be more important than color.  For the pattern to get their attention it should have as much contrast as possible.  That would be black and white.

I'm a believer in using flash material.  It goes black-white-black-white and increases the illusion of motion.

[JasonGotaProblem]

This is an interesting topic and I'm glad it got it's own thread. Loosely related by my understanding bass see green and red only. Color-wise I have the most success with purple lures. I can't back this up empirically but I believe it's because it's a color they can sort of see. I assume it probably looks, to bass eyes, like a weird looking red. Maybe that makes it look enticing?

I also get hits on green lures but it always seems to be small bass hitting those.

[jurelometer]

I throw any surface iron as long as it is a blue and white Salas 7x, or the same color smaller iron for albacore. The iron I have had the best albacore luck with is the blue and white Salas 6x yo-yo. Completely factual, I in no way have caught enough to call it a sample that meets statistical significance, but I do appreciate that I have science in my corner. I am still convinced that disruption of background energy is as significant as anything else. It works for me for decades, don't see why it doesn't work for fish.

At the end of the day, smashed lead with a hook in the right place.
The Man

We seemed to be hard wired to giver lure color every benefit of the doubt

I do agree with the comment about "disruption of background energy", which I was referring to as the halo/backlight effect.  One of the benefits for writing this stuff up is double checking my own assumptions and trying to reconcile the scientific data with the observations from you folk.  My theory on lure color has evolved since starting this thread.

I am warming up to the idea that blue is camouflage in a bluewater environment with no structure, and that the cone cells in tuna eye (concentrated on the front top for looking up) are used for their higher acuity (better resolution) for profile search by looking for the blue/not blue boundary between water and bait.

From an open ocean predator's view, blue is empty water, and anything that is not empty water could be food.  Now the prey has evolved with reflective and blue coloration to look like open water as best as possible, and the predators have evolved to better decipher those boundaries between real and imitation empty water, which would allow them to identify a profile of an individual target that can be pursued and subjected to the taste test.  An underwater evolutionary arms race of hide and seek, sort of like Ron's old line of work.

If this theory is correct, we have two lure coloration strategies.  Either go for completely standing out (any color that is out of range for tuna rod and cone cells - it shouldn't matter much which one), or go for the look of a baitfish slightly failing to  to camouflage, giving a the impression of a short window of opportunity that might fire off a strike reflex.  Tuna brains are all about fast and efficient processing.

Your guess is a good as mine here, but I would tend toward the former in darker conditions and the latter closer to the surface in brighter daylight.  But it is a just a slightly "edjumacated" guess.

This theory is consistent with us all having our favorite colors, but not the same ones, with blues and whites coming into the mix more than others for daytime.

This also partially covers Steve's comment about patterns.  I'll try to respond to the rest next.   I have some chores backing up that I really don't want to do

-J

[Keta]

Good info in this thread.

I have personaly been to 280' below the surface in verry clear water,  not a smart thing for a sports diver but we planed the dive and had tanks staged at decompression stops.  At that deeph all colors with the exception of black and grey are black and grey because the other spectrum does not penetrate.  Black is always black.  This is why deep water bottom fish tend to be red and orange blotched, good camouflage at depth.

On a side note large amounts of glow is not common in nature and my preferance for deep jigs is little or no glow. 

[MexicanGulf]

Very interesting, thanks for sharing this topic.

[Gfish]

Buzzkills are needed to eliminate misconceptions based on flawed human thinking.
Just a thought, but it seems like "something" is missing in our understanding of how fish see and react. Probably just a flawed hunch.
Maybe massive amounts of data are needed to test statistically how fish "might" see and react to it...

[jurelometer]

Since everything is just varying shades of blue, it seems that the pattern would be more important than color.  For the pattern to get their attention it should have as much contrast as possible.  That would be black and white.

I'm a believer in using flash material.  It goes black-white-black-white and increases the illusion of motion.

Well (I think) that depends...

If the predator is looking for a profile, a pattern can break up the profile. Many  (but not all) bluewater species have patterns-so it must serve a purpose.  Stripes on a skipjack, squiggly lines on a mackerel, and so on.  These can work to break up an individual profile, or make it harder to pick out one individual from the school.

For example, single black spots are probably false eyes.  Predators can use the target's eye to determine how to attack (fish don't swim backwards too well).  Species that hang out in schools tend to have the spot near the head- it makes a tight pack of fish look like a wall of eyeballs.  Fish that do not frequently group so tightly tend to have the spot near the tail, presumably so the predator cannot tell which end is the front.

Another example- Marlin are a major predator of dorado (mahi) and have (non) color vision capabilities very similar to tuna.  Taken that green just looks like a fainter blue to this type of vision- that green with random blue dots coloration makes it easy for dorado to see each other, but harder for billfish to make out a dorado profile. It looks like a gaudy paint job to us humans but it is probably camo to a billfish.

If you just want the lure to be seen- any pattern is unlikely to be as effective as a solid color- any color that the rods/cones won't respond to for fish that are looking up or against something like a shallow sand bottom, and something white for fish looking down. Going  between displaying light and dark as the lure wiggles might match the pattern of a disoriented baitfish that is not keeping right side up very well. I think this might be what you are getting at wwith the "illusion of motion" concept?

In regards to flash:  A highly reflective surface is used by fish as camouflage as well.  Each row of scales are at a different angle, reflecting light in different directions(difusion), and also reflecting the colors and shades that are around it, making it  harder for a predator to make out a profile.  Bonefish are the masters of this camouflage.

I am sure that you have seen this one: a bonefish cruising in the grass right in front of you with each scale reflecting seperate bits of sand bottom, coral, seaweed or whatever is around it.  The fish is almost invisible. All you can see is the eye and/or the shadow underneath it. but if it rolls a bit, the change in angle makes a humongous flash that you can see easily at 50 yards,  No doubt that predators key on this as well. A fish that is rolling is vulnerable and easy to find.

Don't know why, but this attraction to flash seems to be species or maybe situation specific.  A 5 lb skipjack will be all over a gigantic chrome crocodile, but you can scare off a 50 lb roosterfish in the shallows if you have more than a strand or two of flash in your 4 inch fly. Sometimes a big flash is better, sometimes no flash, sometimes something in between.  Flash is useful in almost all situations for catching fishermen's money in tackle shops. Right up there with with those "realistic" photo style finishes.

BTW: the vision data is from the scientific literature, but the conclusions and conjecture are mine. While I am doing my best to be logic-based here, other folk may come to different conclusions.  Not trying to convince anyone- just sharing what I have learned and am learning more myself in the process.

It's all good.

-J