Monday, June 13, 2016

What happened to the Blue Pike? by Paul France

On a typical day on the waters of Lake Erie, it is very easy for one to go out and catch a walleye for dinner or sport. This fish lives and feeds near the bottoms of rivers and lakes, like Erie, throughout most of the states east of the Mississippi River and most populations are healthy and ample in size. That was also once the case for the blue pike, a fish that resembled many of the characteristics of the walleye and is said to have been a subspecies of them at one point in history. In the present though, they are considered to be nonexistent due to overfishing, habitat degradation, and competition and have been deemed extinct by the Fish and Wildlife Service. This begs the question, what really happened to the blue pike? Or is their so called disappearance just a fallacy hidden behind the curtain of time and evolution?

If you were to take a stroll down the streets that neighbored the docks of Lake Erie in the 1930s and 1940s, the sights and smells of an overwhelming fishing industry would have filled your senses. The basis of that industry was that of the blue pike, sometimes making up over fifty percent of the total catch harvested (Campbell 1987; Bagheera 2016). Residing in the deep, cool, clear waters of Lake Erie and Lake Ontario, millions of these fish lived and reproduced in a niche that not many fish were able to fill (Belluck 2016). Due to this specialty, the overall population was given an ecological advantage over other species. With such a bounty ripe for the picking, it was human nature to maximize profit to the highest level from such an ample resource. Harvesting without restrictions has its consequences though. Over the years the great size of this population was cut down from its historic levels. It is partly due to this exploitation that this fish is considered extinct today.

Walleye (top) and Blue Pike aka Blue Walleye (bottom).  Photo: John Kerr
The considerable need to harvest great amounts of fish to feed a growing population of people also brings the question of where to put all of those people. Thus, the growth of many towns and cities began within the watersheds that flow into the Great Lakes in which the blue pike resided. Forests were cleared and land was excavated, leaving this fresh barren ground to the will of Mother Nature. Without vegetation to hold it in place, erosion was able to play its part sending ample amounts of sediment down to the lakes, thus allowing siltation to effect the environment in which the blue pike lived in (Bagheera 2016). By blocking sunlight throughout the water column, this newly added sediment was able to indirectly affect the blue pike by smothering out underwater vegetation, ceasing photosynthesis, which served as a basis for its ecosystem. Without a stable supply of food and cover, the blue pike population was once again dealt a harsh blow.

When ecosystems begin to parish and certain species start to disappear, niches began to open up. These openings do not tend to stay around long, especially in the presence of introduced species. The intentional introductions of the Rainbow Smelt into Crystal Lake in 1912 and the Finger Lakes of New York in 1917 were with good intentions at the time, but the eventual competition for resources with the blue pike once they dispersed into the Great Lakes was given no serious thought (Rooney 2009; Fuller 2016). Competition is usually a good thing in today’s world, including the effects of better quality products and lower prices, but in the world of a fish who has seen little if any competition in its existence, it has proven to be detrimental. Being in the same size class of that of the blue pike it is only natural that they both feed on the same resources (Fuller 2016). It is when these two meet over these resources though, that the smelt triumphs. Although they may be small and swim very weakly, smelt can be very aggressive and willing to feed upon any fish that they find. That seems to be the case for those juvenile blue pike unlucky enough to come across a hungry smelt (Stedman 1985). On top of being constantly challenged by fisherman, pressured by an unstable ecosystem, and now the introduction of a competitor that is willing to kill, it is easy to see how such a great population was able to be completely decimated within a half a century, or was time and evolution powerful enough to simply make us believe that was the case?

If you were to compare a photo of a present day walleye and a drawing of what the extinct blue pike looked like, you would notice multiple similarities. It was these similarities that piqued the interest of Amanda Haponski and Carol Stepien when they researched the genetic variation of walleyes to compare genetic material of present day walleye to that of historic walleye and the blue pike to see if they truly did differ enough to consider them a subspecies. Through the use of mitochondrial DNA control region sequences and nuclear DNA microsatellite loci, they were able to determine that blue pike showed no distinguishing alleles that were able to separate them from the same taxonomic group of that of today’s walleyes (Haponski 2014). The blue color and thought to be distinguishing characteristics were just mere phenotypes of the relative time for the walleye and as time always does with everything else, it changed these phenotypes as the walleye evolved over the years to its changing environment.

Cut down by overfishing, pressured by habitat degradation, and challenged by new competitors, the “blue pike” sure faced its fair share of trials and tribulations over time. Like most extant species of today though, it was able to adapt to its changing environment and survive as the walleye we fish for on any typical day in the waters of Lake Erie.

Bagheera. “The Blue Pike.” (accessed April 4, 2016).
Belluck, Pam. “In Angler’s Freezer Since ’62, Fish May Refute ‘Extinction’.” (accessed April 4, 2016).
, : Status of the blue walleye Stizostedion vitreum glaucum in Canada. Canadian  Field-Naturalist 101: 245-252
Fuller P. and E. Maynard. “Osmerus mordax”. USGS Nonindiginous Aquatic Species Database. (accessed April 4, 2016).
Haponski, A. E., Stepien, C. A. 2014. A population genetic window into the past and future of the walleye Sander vitreus: relation to historic walleye and the extinct “blue pike” S. v.glaucus.” BMC Evolutionary Biology 14:133.
Rooney, R. C.; Paterson, M. J. 2009. "Ecosystem effects of rainbow smelt (Osmerus mordax) invasions in inland lakes". Can. Tech. Rep. Fish. Aquat. Sci. 4:1–20.
Stedman, R.M., and R.L. Argyle. 1985. Rainbow smelt (Osmerus mordax) as predators on young bloaters (Coregonus hoyi) in Lake Michigan. Journal of Great Lakes Research 11(1):40-42.

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