Fish Science Geek Out

Northern

Northern

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Wasn't sure where to post this, but I feel like there might be at least a couple folks on here that find this as cool as I do...serious nerd warning!

In the art forum, I recently posted a couple pics of fins:
20191203_164529.jpg
blue fin 2 %282%29.JPG
Those are not color manipulated, and they're not tropical. Those are of walleye fins in NW Ontario!
We were on a 2017 fly-in trip, the only cabin on the lake, so there was no one to ask if this was normal. My sibs and I have fished ON for decades - but this was the farthest north we've been. About 10% of the 'eyes we were catching had these brilliant blue fins, and this blue goo came off on your hands and on the cleaning table.
(Of course, after discussing how bizarre that was, and that we had no idea what it could be, we ate them anyway 😜)

Now, there used to be such a thing as Blue Walleye, but they apparently went extinct or almost extinct decades ago, and were more an all-over bluish gray phase, not this bright indigo. We knew that, and these were definitely not that.

When I got home, I did some internet research, and found some very recent articles about a newly discovered protein isolated from - you guessed it - walleye (Sander vitreus) fins!

Turns out that sandercyanin is a fluorescent protein with some super cool unique properties. As a molecular biologist, protein engineer, and walleye enthusiast myself, I was smitten! 🤓

If you're interested, here's a paper to start with: https://www.pnas.org/content/113/41/11513

A very brief summary, though: Sandercyanin is a very small protein secreted in the mucous layer of some walleye. Four of these molecules will non-covalently bind to a ligand called biliverdin, which is a product of UV radiation-induced breakdown of heme in the blood. The protein complex formed by that binding is not only bright blue, but under UV light will undergo a huge spectral shift to fluoresce as red!
(I won't bore you with all the other interesting properties of this molecule, you can read the papers if you like.) There's a theory that this is a recent adaptation to the increased UV exposure of a thinning ozone layer up north; that the sandercyanin absorbs UV and acts as a natural sunscreen. 😎

We're headed back up that way in August, after having our trip canceled for the last 2 years due to Covid. I'm planning to bring a strong UV lamp in the appropriate wavelength, and I really want to try to get photos of a glowing red walleye! How cool would that be??
 
That is cooler than hell. I'm kind of tuned to this sort of thing now, as I just finished reading The Tangled Web by David Quammen. I was struck by the really strange implications that molecular phylogeny has produced in the last 40 years. I realize that this is a different kind of adaptation, but it just goes to show that life is cooler and more complex than we think.
 
PhilR said:
That is cooler than hell. I'm kind of tuned to this sort of thing now, as I just finished reading The Tangled Web by David Quammen. I was struck by the really strange implications that molecular phylogeny has produced in the last 40 years. I realize that this is a different kind of adaptation, but it just goes to show that life is cooler and more complex than we think.
Click to expand...
Went and ordered that book just now - thanks!
 
Northern said:
Went and ordered that book just now - thanks!
Click to expand...
Let me know what you think. I've always liked his writing, starting way back in Outside magazine before it became a gear catalog.
 
This is so cool. Thanks for sharing @Northern
Did the rest of the walleye look all colored up? or just the fins?
In the bottom photo it looks like the caudal peduncle is all colored up too.
 
Long_Rod_Silvers said:
This is so cool. Thanks for sharing @Northern
Did the rest of the walleye look all colored up? or just the fins?
In the bottom photo it looks like the caudal peduncle is all colored up too.
Click to expand...
It's actually expressed in the slime coat, which is pretty thin on a walleye's body (they feel rough, not slick.) I think I remember reading that the protein just doesn't show up much against the darker coloration of the rest of the fish, so it was just more obvious with the sunlight shining through the thin fin membranes, or where it sort of pooled. Those pics were taken on the cleaning table. (Mmmmm...walleye) You could scrape the blue goo off with the fillet knife. They kind of glistened bluish in the sun, though!
I'll take better pictures if we encounter them again this summer. Different lake, but same area.
 
Northern said:
Wasn't sure where to post this, but I feel like there might be at least a couple folks on here that find this as cool as I do...serious nerd warning!

In the art forum, I recently posted a couple pics of fins:
View attachment 3967
View attachment 3968
Those are not color manipulated, and they're not tropical. Those are of walleye fins in NW Ontario!
We were on a 2017 fly-in trip, the only cabin on the lake, so there was no one to ask if this was normal. My sibs and I have fished ON for decades - but this was the farthest north we've been. About 10% of the 'eyes we were catching had these brilliant blue fins, and this blue goo came off on your hands and on the cleaning table.
(Of course, after discussing how bizarre that was, and that we had no idea what it could be, we ate them anyway 😜)

Now, there used to be such a thing as Blue Walleye, but they apparently went extinct or almost extinct decades ago, and were more an all-over bluish gray phase, not this bright indigo. We knew that, and these were definitely not that.

When I got home, I did some internet research, and found some very recent articles about a newly discovered protein isolated from - you guessed it - walleye (Sander vitreus) fins!

Turns out that sandercyanin is a fluorescent protein with some super cool unique properties. As a molecular biologist, protein engineer, and walleye enthusiast myself, I was smitten! 🤓

If you're interested, here's a paper to start with: https://www.pnas.org/content/113/41/11513

A very brief summary, though: Sandercyanin is a very small protein secreted in the mucous layer of some walleye. Four of these molecules will non-covalently bind to a ligand called biliverdin, which is a product of UV radiation-induced breakdown of heme in the blood. The protein complex formed by that binding is not only bright blue, but under UV light will undergo a huge spectral shift to fluoresce as red!
(I won't bore you with all the other interesting properties of this molecule, you can read the papers if you like.) There's a theory that this is a recent adaptation to the increased UV exposure of a thinning ozone layer up north; that the sandercyanin absorbs UV and acts as a natural sunscreen. 😎

We're headed back up that way in August, after having our trip canceled for the last 2 years due to Covid. I'm planning to bring a strong UV lamp in the appropriate wavelength, and I really want to try to get photos of a glowing red walleye! How cool would that be??
Click to expand...
I studied biochemistry, spent 7 years doing biomed research at UW, and now teach HS biology. This is right up my alley, thanks for sharing!
 
More for us geeks, another very cool finding (though technically not fish):

www.nature.com

Giant sponge grounds of Central Arctic seamounts are associated with extinct seep life - Nature Communications

This study reports the discovery of dense sponge gardens across the peaks of permanently ice-covered, extinct volcanic seamounts of the Langseth Ridge and on the remnants of a now extinct seep ecosystem. Using approaches to sample and infer food and energy sources to this ice-covered community...
www.nature.com www.nature.com

cheers
 
Another, peripherally related to fishing (at least as far as that's when mosquitoes are a concern for me.)
http://www.sci-news.com/biology/mosquito-visible-spectra-10525.html

Although, here's my personal anecdote on that.
At a central WA lake rife with mozzies, I was wearing knee length capris. I had a calf muscle injury, so was also wearing a bright blue compression sleeve on one leg, the other bare from knee down. Both had been sprayed with bug dope.
While at the launch, I got fifteen bites through the compression sleeve, but zero on the bare leg!
Maybe that shade was more "cyan" than blue?
In any case, I now avoid wearing that color in mozzie country!
 
Northern said:
Another, peripherally related to fishing (at least as far as that's when mosquitoes are a concern for me.)
http://www.sci-news.com/biology/mosquito-visible-spectra-10525.html

Although, here's my personal anecdote on that.
At a central WA lake rife with mozzies, I was wearing knee length capris. I had a calf muscle injury, so was also wearing a bright blue compression sleeve on one leg, the other bare from knee down. Both had been sprayed with bug dope.
While at the launch, I got fifteen bites through the compression sleeve, but zero on the bare leg!
Maybe that shade was more "cyan" than blue?
In any case, I now avoid wearing that color in mozzie country!
Click to expand...

Knew white and green were colors to wear to avoid 'squitos, but it's tough to stop exhaling ;)

cheers
 
Northern said:
Turns out that sandercyanin is a fluorescent protein with some super cool unique properties. As a molecular biologist, protein engineer, and walleye enthusiast myself, I was smitten! 🤓

If you're interested, here's a paper to start with: https://www.pnas.org/content/113/41/11513

A very brief summary, though: Sandercyanin is a very small protein secreted in the mucous layer of some walleye. Four of these molecules will non-covalently bind to a ligand called biliverdin, which is a product of UV radiation-induced breakdown of heme in the blood. The protein complex formed by that binding is not only bright blue, but under UV light will undergo a huge spectral shift to fluoresce as red!
(I won't bore you with all the other interesting properties of this molecule, you can read the papers if you like.) There's a theory that this is a recent adaptation to the increased UV exposure of a thinning ozone layer up north; that the sandercyanin absorbs UV and acts as a natural sunscreen. 😎
Click to expand...
Hi Northern,
Several PNW fish have blue flesh too. Ling cod and several of the greenlings and cabezon and some of the other cottid species (from my personal experience) are well-known to have blue flesh. None are known to secrete a blue slime though. The blue color in these species is also due to biliverdin; biliverdin has been shown to have a number of interesting health-impacts in humans. The scientific literature on the frequency of the blue coloration and its possible significance is quite thin in these marine species. You can read an interesting summary of some of this information on ling cod here. In summary, the blue coloration is more common in female ling cod (and female cabezon too apparently). It also appears to be a more common phenomenon in fish caught in shallow water or that were smaller. Hypotheses to explain the blue coloration include a) absorption of UV (but far less relevant in the deeper waters of the ocean), b) dietary differences, c) nutritional stress, or d) genetics.
Very cool.
Steve
 
Cabezon said:
Hi Northern,
Several PNW fish have blue flesh too. Ling cod and several of the greenlings and cabezon and some of the other cottid species (from my personal experience) are well-known to have blue flesh. None are known to secrete a blue slime though. The blue color in these species is also due to biliverdin; biliverdin has been shown to have a number of interesting health-impacts in humans. The scientific literature on the frequency of the blue coloration and its possible significance is quite thin in these marine species. You can read an interesting summary of some of this information on ling cod here. In summary, the blue coloration is more common in female ling cod (and female cabezon too apparently). It also appears to be a more common phenomenon in fish caught in shallow water or that were smaller. Hypotheses to explain the blue coloration include a) absorption of UV (but far less relevant in the deeper waters of the ocean), b) dietary differences, c) nutritional stress, or d) genetics.
Very cool.
Steve
Click to expand...


I thought I heard that the blue in lings/Cabs was from eating squid and or octopus, and also crab shells can produce it too. I know Cabazon like to eat crabs but do lings?

I have caught male lings, well in the slot limit so assumed male that were blue, they are definitely a better tasting fish in my experience!
 
Paige said:
I thought I heard that the blue in lings/Cabs was from eating squid and or octopus, and also crab shells can produce it too. I know Cabazon like to eat crabs but do lings?

I have caught male lings, well in the slot limit so assumed male that were blue, they are definitely a better tasting fish in my experience!
Click to expand...
Hi Paige,
Biliverdin, a green-blue pigment is a natural byproduct of the recycling of the heme groups of hemoglobin. The interesting question is why specific individuals have high enough circulating levels of color their skeletal muscle or blood or skeleton. There is a review of blue-green blood in fishes but I only have access to the abstract.
Steve
 
Cabezon said:
Hi Northern,
Several PNW fish have blue flesh too. Ling cod and several of the greenlings and cabezon and some of the other cottid species (from my personal experience) are well-known to have blue flesh. None are known to secrete a blue slime though. The blue color in these species is also due to biliverdin; biliverdin has been shown to have a number of interesting health-impacts in humans. The scientific literature on the frequency of the blue coloration and its possible significance is quite thin in these marine species. You can read an interesting summary of some of this information on ling cod here. In summary, the blue coloration is more common in female ling cod (and female cabezon too apparently). It also appears to be a more common phenomenon in fish caught in shallow water or that were smaller. Hypotheses to explain the blue coloration include a) absorption of UV (but far less relevant in the deeper waters of the ocean), b) dietary differences, c) nutritional stress, or d) genetics.
Very cool.
Steve
Click to expand...
Hi @Cabezon ,
Just to be clear, these walleye do not have blue flesh. The protein/biliverdin complexes found in lingcod, cottids, etc., plus some lizards, and many frog species are, I believe, mostly known to involve serpins, and are not fluorescent, and seem to permeate blood, flesh, bone, etc.
Sandercyanin is a secretory protein, as evidenced both by its physical location on the fish, and the fact that the AA sequence contains a secretory signal peptide.
As a free monomer, sandercyanin is colorless, only becoming bright blue when, in the presence of biliverdin, it forms tetrameric complexes, with each sandercyanin molecule cradling a molecule of biliverdin. Under exposure to UV around the 375nm wavelength, that complex fluoresces brilliant red.

I cannot believe that the researchers never took photos of the whole fish under 375nm UV. I may buy a UV dive light and try to do this, just because glowing red walleye 😃🤓😈
 
I have long been super interested in blue lingcod. Mostly just because I think they are super cool! I've read as much as this non scientist can, and from what I've gathered the scientists know what causes the blue flesh, but nobody has totally established why it happens.

Personally the diet theory never really seemed solid to me because it would seem that if one lingcod in a particular area had access to, and was eating a lot of squid/crab then I would think a higher percentage of other lings in the same area would also be blue, but at least IME I've never found that to be the case. I've never encountered a high density of blue lings in any particular area. More common is to catch 12 lingcod from an area on any particular day, and maybe one of them is blue. I dunno, just my un scientific thoughts lol.

Again anecdotal, but as Steve mentioned regarding depth, I've caught very few blue lingcod deeper than about 250', with the bulk of them coming in 180' or less.

I've heard a lot of people claim that they prefer the taste of the blue lings over the standard flesh, but never really believed it. Always assumed there was a placebo affect going on. Last season we did a blind taste test with our crew in Westport and not one of us was able to notice a difference. Not that that proves anything at all but it was interesting. Always thought it was neat the way the blue flesh turns white when put on heat.

Lingcod are probably my favorite fish. Just love those things.




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