The Blue Walleye
The Blue Walleye was considered a separate species in 1926, although it was later downgraded to a subspecies. Listed as an endangered species by the United States in 1967, and declared extinct in 1985.
However, genetic analyses conducted in the 21st century show that the blue walleye is NOT genetically different from the yellow walleye.
The last Blue Walleye to be officially recognized as a Blue Walleye by the MNR was caught in Lake Erie in 1965. MNR is an acronym for Ontario Ministry of Natural Resources.
The “non specie” fish appears to be increasing in number in Canada and the Northern US.
“We’re finding it in Canadian river systems where it was not present a decade ago, and receiving more reports from the northern US”, says Dr. Wayne Schaefer, professor of biological sciences at the University of Wisconsin-Washington Country. (http://wayneschaefer.blogspot.com/2019/04/the-story-of-our-research.html)
The blue walleye is characterized by blue shading located mainly on the upper body, most noticeably on the dorsal fins and top part of the tail.
Blue walleye retain this colour due to a lack of yellow skin pigment and a blueish protein in the mucus coating on its skin.
This protein dubbed “sandercyanin,” “sander” coming from the genus of the walleye and “cyanin” being the Greek word for blue, does not affect the health or taste of the fish.
Although it is unknown what exactly the sandercyanin is for, most researchers seem to believe it may aid in protecting the walleye from ultraviolet (UV) radiation from the sun.
It is believed that blue walleyes could be protecting themselves by excreting excess amounts of the very substance caused by its radiation.
Sandercyanin is generally at it’s highest concentration in blue walleye during summer months when the sun is out the most. It is also only located on the walleye’s dorsal fins.
It is believed that a decrease in the zone layer is responsible for the increase in the number of blue walleye.
A dark bluish colored walleye exists in some waters – Dawn Lake near Armstrong, ON – of the Canadian Shield. A mucosal pigment, named “sandercyanin”, was hypothesized to be the source of the color, but this has not been confirmed.