Blue walleye mucous could be a sun block for fish says American researcher Social Sharing

CBC Reports: A study into an unusual form of the common walleye, that is blue in colour, has revealed some traits that could make it important to medical research.

Wayne Schaefer, a researcher from the University of Wisconsin, said the blue walleye may have its own form of natural sunscreen.

He said the mucous that creates the blue colour – called Sandercyanin – is a form of protection for the fish.

“From an ecological point of view it appears the Sandercyanin protects walleye in northern areas of the earth from ultra violet radiation,” he said. “Which is more abundant coming in from our North Pole than in the mid-latitudes of North America. It’s a protective function. It’s one of the little miracles of nature.”

Schaefer said the blue coloration is caused by a protein secreted into the mucous. The blue pigment was found in yellow walleye as well as blue walleye from the same lakes.

“In all the lakes we have studied with blue walleye, less than half of the walleye present, maybe a quarter or one-fifth of the walleye present in the lake, are blue” he noted.

A fish biologist by trade, Wayne Schaefer first came into contact with blue walleye while fishing near Armstrong, in Northwestern Ontario, back in 1993.

“I’m a sport fisherman,” he said, “and I began catching walleye that were blue in colour, rather than yellow, and that piqued my interest.”

Schaefer had studied the “blue pike” of Lake Erie as a graduate student.Those fish were a sub species of the common walleye, but were blue in colour instead of the standard yellow.

The blue pike were an important commercial species in the early 1900s in Lake Erie, but were extinct by the mid-1950s. However, the blue tones Schaefer noted in the walleye from northern Ontario made him wonder if it was the same species as the now extinct Lake Erie fish. He packaged a few of the fish he caught up and brought them back to the states. So began his research into northern Ontario’s blue walleye.

“The first question that we wanted to answer was, is this the same species as was in Lake Erie?” said Schaefer. “So we contacted an expert in walleye genetics. Genetics is the true test. Not colour, not behaviour, but rather DNA sequencing.”

The fish Schaefer had caught were genetically compared to archived samples of blue pike stored at the University of Michigan.

“They were two different things,” says Schaefer.” The blue walleye of northern Canada are just a colour variation of a regular walleye.”

However, there were other things about the blue walleye that would soon be revealed.

“The colour – to my surprise – was found in the mucous of the fish.” he said. “Not in the scales of the fish.” Schaefer said the first specimens he handled looked grey in colour, rather than bright blue. Yet the were different enough that he put them in zip lock bags and brought them back with him.

“By the time they got back to my lab in Wisconsin, in the zip lock bag, there was bright blue colour in the fluid in the bag,” he said. “Along with the fish.I don’t know any other report of any other colour in the mucous of fish species.”

Schaefer said the presence of blue walleye in watersheds is largely geographic.

He said the blue walleye he has examined and heard about are largely north of the Canadian border.

Schaefer said south of the Canada / US border there is very little blue colouration in walleye.

Schaefer said they initially thought the mucous might be caused by a symbiotic micro-organism in the mucous of the fish like a bacterium or an algae. That was not the case.

“Early in this research, I thought that Sandercyanin might fluoresce in ultraviolet radiation” he said.

“In 2008, at the University of Iowa in their microscope lab, they radiated a fresh sample of walleye mucous with ultra-violet light. Glowing back at us bright as could be, were red cells of Sandercyanin. It was one of the most amazing experiences of my professional career.”

Schaefer said at about that same time, researchers at the University of California had published work on green fluorescent protein found in jelly fish. That research went on to be so useful, the researchers received a Nobel Prize. Schaefer said the medical aspect of the protein is it can be cloned, and its genetic sequence determined.

The genes for the fluorescent proteins are then packaged and made available to medical researchers. They act as a marker or a tracker.

Schaefer said Sandercyanin has great potential for medical research, but it needs more work. “We just have to tweak it,” he said.

Schaefer noted Sandercyanin does not harm the health or taste of the fish and is produced seasonally, with more in summer than winter.

Source: CBC.CA

Photo Credit:  W Schaefer

5 Replies to “Blue walleye mucous could be a sun block for fish says American researcher Social Sharing”

  1. As I stated previously, I am not an Ichthyologist by any means, but the above synopsis concerning the Sandercyanin in the mucous of these fish rings a bell.

    A few statements appear to be of primary importance….

    First – From an ecological point of view it appears the Sandercyanin protects walleye in northern areas of the earth from ultraviolet radiation, which is more abundant coming in from our North Pole than in the mid-latitudes of North America. It’s a protective function. It’s one of the little miracles of nature.

    Second – “The colour was found in the mucous of the fish. Not in the scales of the fish. The first specimens looked grey in colour, rather than bright blue.

    Third – The blue walleye examined and heard about are largely north of the Canadian border.

    Fourth – Sandercyanin does not harm the health or taste of the fish and is produced seasonally, with more in summer than winter.

    So, let’s deal with the first and second statements. 1) From an ecological standpoint, it’s a protective function. It’s one of the little miracles of nature. 2) The colour was found in the mucous of the fish. Not in the scales of the fish….We should all be aware by now how the mucous (slime) protects a fish from the harmful and invasive bacteria in it’s environment. It is their first line of defense, since their scales offer little protection in this instance, similar to our own skin. A cut in our epidermis would invite infection as it would with a break in the fish mucous. One conclusion, the blue coloration in the mucous membrane could very well be a reaction to the bacteria in the water. That could explain the “Blue Boost” and why the coloration is in the mucous and not the fish itself.

    With that in mind, here are some facts I came up with concerning water and ultraviolet light.

    Water does protect fish from U.V. light but not very effectively when you are only slightly under the water’s surface. How much UV radiation is blocked by water is dependent on the “kind and condition” of the water. So the transparency of the water, the amounts of chlorophyll and other light absorbing pigments in the water, reflection off the water’s surface (albedo), and the wavelengths of the UV light, all affect the depth of penetration of the UV light into the water.

    Studies of UV penetration into seawater have shown:

    Seawater is an “effective filter of shorter UV wavelengths”.
    UV penetrates deeper in open ocean than in arctic oceans, and least in coastal waters.
    In clear ocean waters, phytoplankton can live down to depths of about 660 ft. Beyond that, not enough light is available for photosynthesis. However, photosynthesis in the ocean depends much more on the visible wavelengths of light, especially violet, blue and blue-green. The longer wavelengths of light (green, yellow and red) are attenuated quickly. That’s why at deeper than 60 ft, everything looks blue (unless of course, you have brought your light with you).
    Shorter wavelength UV light penetrates well to about 30 ft (10 m). At 130 ft (40m), only about 1% of UV light is detectable. Longer wavelength UV light (390) penetrates better than shorter wavelength UV light (290nm).

    So water blocks UV light; turbid water and colored water block UV better than very clear water; longer wavelength UV light (UVA) penetrates deeper than shorter wavelengths (UVB). And you have to go pretty deep (about 30ft) to eliminate more than half the UV light from the sun in clear waters….I would say, in effect the fish’s mucous is somewhat of a sun block, The second conclusion, the blue color could very well be a chemical reaction in the mucous to increase this U.V. protection. That could explain why some fish in certain lakes are blue while others are not. The water the Blue Walleye reside in may be much clearer, requiring a “Blue Boost” per se.

    Now let’s take a look at the third and fourth statement again….4) Sandercyanin does not harm the health or taste of the fish and is produced seasonally, with more in summer than winter. 3) The blue walleye examined and heard about are largely north of the Canadian border.
    This one appears to be self evident. In the summer, the sun rays hit the earth’s atmosphere at an acute angle allowing more Ultraviolet ray penetration….In the winter the angle is more obtuse with much less U.V. penetration. The protective mucous on the fish reacts to amount of U.V. light penetration. This could account for another “Blue Boost”in some rather than others.

    Note : The earth’s atmosphere also converts these “light” wavelengths into “heat” wavelengths since the heat from the sun can not travel through the vacuum of outer space. It’s the similar principle as concentrating the sun’s light rays with a magnifying glass. You get extreme heat…. The sky is blue because our atmosphere reflects the blue portion of the spectrum. Same reason as why water appears blue.

    Now you know how all this information came “light”!

  2. My level of curiosity continues to climb. Something definitely smells fishy!

    As I pointed out in another blog, “proteins” are a form of “Amino Acids”. Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid. The key elements of an amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other elements are found in the side chains of certain amino acids. About 500 naturally occurring amino acids are known. The alpha amino acids are the most common form found in nature.

    Now taking that information into account, let’s try to apply it to a few things mentioned above.

    Statement # 1
    From an ecological point of view it appears the Sandercyanin protects walleye in northern areas of the earth from Ultraviolet radiation…

    I would say, maybe. So, let’s keep ultraviolet radiation temporarily out of the equation for the moment. Water quality and the bacteria count in the ecosystem is worth looking into in the meantime.

    Statement #2
    The blue coloration is caused by a “protein” (Amino Acid) secreted into the mucous. The blue pigment was found in yellow walleye as well as blue walleye from the same lakes. They initially thought the mucous might be caused by a symbiotic micro-organism “in” the mucous of the fish like a bacterium or an algae. That was not the case. Schaefer said the first specimens he handled looked “grey” in colour, rather than “bright blue”. Yet they were different enough that he put them in zip lock bags and brought them back with him.

    Most interesting. If this blue pigment is present in both the Yellow and Blue Walleye, why the difference in coloration at any one time? I suspect a connection to a natural antibiotic in the mucous protein (not a bacterium) since the biggest question here is protection for the fish. Could there be something these Blue (grey) Walleye are fending off that has entered the watershed? Is the mucous reacting to an external bacterium? That is highly likely! Remember the article says, The blue coloration is not in the fish itself.

    Which leads to….

    Statement #3
    In 2008, at the University of Iowa in their microscope lab, they radiated a fresh sample of walleye mucous with ultra-violet light. Glowing back at us bright as could be, were red cells of Sandercyanin.

    If this has anything to do with Ultraviolet radiation, why do the Sandercyanin cells in the Walleye mucous glow a bright red and not blue when exposed to this type of light?
    Note: If you recall these blue tinted Walleye were once extremely rare. Ultraviolet radiation has been around for millions of years. Surrounding human activity, such as industrial run off in all aspects, can and will affect the the water quality.

    Let me give you an example. While vacationing with relatives up on Lake Ayrd in Northeastern Ontario, we notice small parasitic worms in the flesh of the fish we caught. Mind you, they were only about 1/8 of an inch but they were potentially fatal to the fish stock. We were also made aware of a nearby cattle farm. Further investigation revealed the worms originated in the intestines of the cattle. How they entered the fish is anyone’s guess. My estimation would point to the worms eating their way through the fish’s mucus membrane.

    I have also observed how water quality effects the taste of a fish. Some Lake Erie perch caught at different times of the year taste stronger than at other times. My first thought: Maybe it was what these fish were eating. Yes, that is possible. Second thought: It was from the pollution in certain areas of the lake in which the fish passed through during it’s life cycle. Consequently, could this stronger taste originate from the fish’s internal antibiotic immune system like that of any other living creature? Absolutely!

    Yes I have my suspicions, since I’m not totally convinced this has anything to do with ultraviolet radiation. I’m not saying these Scientists are wrong in their assessments but the more questions we ask and ideas that we thrown into the Amino Acid mixture, it always comes down to one basic scientific formula of nature….

    One’s ability to cipher a scientific code is not in the biological equation itself, but in one’s own intelligence to perceive the unknown.

  3. One more quick comment here. Scientific knowledge of any kind should always be tempered with common sense and logic. As I have repeated many times. “A man’s intelligence is not measured by how much knowledge he has acquired. It is measure by how wisely he has applied that knowledge.”

  4. Okay boys and girls! The deeper I dig into this little “Amino Acid” conundrum, the twists and turns really begin to have a chemical reaction to my thought processes. So, listen closely…..

    Remember my reference as to how vitally important the process of “Observation” has become recently in some of my comments and should be for every angler? Well, this may blow your mind totally!! In the meantime, those Scientists might want to recalculated their conclusions.

    The date April 20, 2019….As usual the wife and I wake up to watch several of our favorite Saturday morning fishing shows. Hot coffee and toast at the ready. The T.V. tuned to Global channel 41.

    First on the agenda was “Adventures North”. The hosts were fishing for Walleye up on Lake Winnipeg in the middle of winter. The ice, approximately 4 to 5 feet thick, was snow covered.
    The Walleye these boys were pulling up is what stared this whole thing rolling into a technicolor extravaganza.
    Walleye that were younger and roughly 12 to 18 inches long were bright “greenish” in color.
    Walleye that were older and roughly 24 inches and longer were bright “yellow” or “gold”.
    None appeared “blue”!

    Next up was “Real Fishing” with Bob Izumi. He was fishing Walleye out on Georgian Bay, during the winter season, with his brother Wayne and a few other buddies. The ice about 4 to 5 feet thick.
    Walleye 14 to 18 inches long were also “greenish” but much lighter.
    Walleye that were 20 to 24 inches or longer were “yellow or “gold” but quite a bit lighter.
    Neither were any of these specimens “blue”.

    Now let’s flip over to the Fish’n Canada show. Pete Bowman was fishing Walleye at Chapleau Resort up on Borden Lake in the Algoma District during the summertime round about, where he ran into a few showers. Now, you have all heard tell of the saying “That’s a horse of a different color?” Well, “Pete’s catches were certainly some “fish of a different color for sure.”
    The larger Walleye were “black and gold”
    The smaller Walleye were “green and gold”
    And no, none had that odd blue coloration.

    What gives? Winter or Summer the colors are somewhat similar but there are distinctive variations. It kind of puts a kink into that “Ultraviolet” theory. If you recall, these blue tinted Walleye were once extremely rare. Ultraviolet radiation has been around for millions of years.

    Could the coloration differences be related to what these fish are consuming? Should the color stain of the water be of some concern? It can’t be the time of year, since both the “Adventures North” and “Real Fishing” shows were shot during the winter, while Pete was out in Algoma getting a soaker.

    Remember what it implied in the above article….
    “The blue pike were an important commercial species in the early 1900s in Lake Erie, but were extinct by the mid-1950s. However, the blue tones Schaefer noted in the “walleye” from northern Ontario made him wonder if it was the same species as the now extinct Lake Erie fish.”….Note:This statement alone would indicate the blue coloration in the Walleye’s mucus membrane has nothing to do with “Ultraviolet Radiation”.
    It appears to point to a gene mutation in the mucus membrane, the fishes immune system/pollution, their food consumption, or color stain of the water in which they reside as I have previously stated. Take for example the “Pink Flamingo”. They are actually white. The obtain their pink coloration from the food the eat. The feathers become pink not the bird itself.
    More so, it can not be a new species of Walleye since the article states,”The colour was found in the mucous of the fish….Not in the scales of the fish. The first specimens handled looked grey in colour, rather than bright blue.”
    Again, this statement would imply all “blue” mucus Walleye are of the same species as any other Walleye. Remove the mucus and you have yourself a typical Walleye.

    So, where is the real “Blue Walleye” species? Actually, I would conclude there is no such creature other than an Amino Acid Affliction caused by the fish’s H2O environment.

    Remember Lads and Lasses, “Confusion occurs, when citizens pursue a habitually difficult answer to a profusely simple question.”

  5. I’ll slide another thought in here just to keep this thing going. Scientists have argued that Blue Walleye and Pike are caused by exposure to “Ultraviolet Light”. If this were true, which I highly doubt, then all Walleye and Pike should be “blue”…. as we see, they are not! They only show up at sparse intervals.

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