Thursday, March 05, 2015

Journal Article, 2015

Follow this link to read the full text:

ABSTRACT Several fish species, including the walleye (Sander vitreus), have “yellow” and “blue” color morphs. In S. vitreus, one source of the blue color has been identified as a bili-binding protein pigment (sandercyanin), found in surface mucus of the fish. Little is known about the production of the pigment or about its functions. We examined the anatomical localization and seasonal variation of sandercyanin in S. vitreus from a population in McKim Lake, northwestern Ontario, Canada. Skin sections were collected from 20 fish and examined histologically. Mucus was collected from 306 fish over 6 years, and the amount of sandercyanin was quantified spectrophotometrically. Sandercyanin was found solely on dorsal surfaces of the fish and was localized to novel cells in the epidermis, similar in appearance to secretory sacciform cells. Sandercyanin concentrations were significantly higher in fish collected in summer versus other seasons. Yellow and blue morphs did not differ in amounts of sandercyanin, suggesting that the observed blue color, in fact, arises from lack of yellow pigmentation in blue morphs. The function of the sandercyanin remains unclear, but roles in photoprotection and countershading are consistent with available data.

Sunday, January 31, 2010


Production of Sandercyanin is seasonal and peaks in late summer. The graph plots absorbance of Sandercyan by date and indicates peak production in late summer all three years. The photo shows jars of slime from individual walleye captured in both March and August indicating greater production of blue pigment in August.


Blue pigment (Sandercyanin) is produced in membrane-bounded vesicles (440x) just posterior (toward tail) to each dorsal spine and next to an adjacent blood vessel.

Tuesday, March 04, 2008


Blue walleye of Canada are genetically different than the extinct "blue pike" of Lake Erie. They are albino for yellow color and have blue color in the mucous of their skin. The blue color forms on the dorsal (upper) part of the body and is particulary noticable in the two dorsal fins and the upper part of the tail.

Research Update

January 31, 2010

1. Two factors contribute to the blue color in walleye:
a. lack of yellow pigment in the skin of the fish.
b. presence of blue pigment in the skin mucous of the fish.

2. We have identified the blue pigment in the mucous as a new protein never before described in the literature. We have named the pigment "Sandercyanin". Sander is the genus name for walleye and cyanin means blue in Greek.

3. Sandercyanin consists of a large lipocalin protein which carries "biliverdin". Biliverdin is a normal excretory product secreted in urine of all vertebrate animals. It forms from the breakdown of "heme", a blood protein.

4. Sandercyanin occurs in the mucous of walleye in many lake and river systems in Ontario, Quebec and Manitoba. It is equally present in both blue and yellow walleye in any given lake or river system.

5. Sandercyanin appears to be moving south across the Canadian-U.S. boarder into upper Minnesota and upper Michigan.

6. Sandercyanin does not harm the health or taste of the fish.

7. Sandercyanin is produced seasonally, with more in summer than winter. It is produced only on the dorsal (upper) part of the fish, above the lateral line. Specifically, Sandercyanin is produced on a line just posterior (toward tail) to each spine in the dorsal fins.

8. One factor that causes the breakdown of heme to biliverdin is exposure to ultraviolet (UV) radiation from the sun. The earth is normally protected from UV radiation by ozone in the upper atmosphere. In recent years ozone "holes" have been noted over both the north and south poles as a result of CFCs (chlorofluorocarbons) entering the atmosphere. In some species of animals, biliverdin is known to act as a photo-protectant.

9. It is possible that walleye in Canada use, as a sun screen, the very chemical which forms in their blood from exposure to too much sun. This conclusion is still only speculation but it is our best hypothesis.

Tuesday, March 21, 2006

'Blue Walleye' Makes News

Our work was recently cited in a March 19, 2006 article in the St. Paul Pionner Press. Read the Article Here

Wednesday, March 08, 2006

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Wednesday, February 08, 2006

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