The blue walleye (Sander vitreus glaucus) sometimes erroneously called the blue pike, was a subspecies of the walleye that went extinct in the 1970s. Until the middle of the 20th century, it was a commercially valuable fish with about a half million tonnes being landed during the period from about 1880 to the late 1950s, when the populations collapsed.
The fish was endemic to lakes Erie and Ontario of the Great Lakes region of the U.S. and Canada, including the inter-connecting Niagara River, but most especially to Lake Erie where it sometimes represented more than 50% of the commercial catch. The subspecies was apparently extirpated by about 1970 through a combination of anthropogenic eutrophication, overfishing and competition with the introduced rainbow smelt (Osmerus mordax). The subspecies is now considered extinct.
There are occasional reports of blue walleye being caught from waters in the Great Lakes basin. This is due to the fact that many yellow walleye populations also contain a colour variant with a bluish colour. The actual blue walleye, however, was said to be distinguishable from the yellow walleye by various meristics and morphometrics; things which the blue colour variant of the yellow walleye seems not to share. Reportedly, some of the meristic and morphometric differences may simply have been artifacts of the different growth rates of yellow and blue walleyes. The clearest evidence, though, is that the blue walleye, whatever its taxonomic status, has been lost. Nonetheless, an investigation of genetic material from preserved blue walleye specimens is currently underway in several research facilities in an effort to decipher the true status of the populations.
To date, none of the bluish-coloured walleyes recently captured has been shown to be a blue walleye, despite the fact that at least one organization in the US is offering a reward for the successful capture of a blue walleye specimen. A United States Fish and Wildlife Service recovery plan in the mid-1970s was unable to find any certain evidence of the blue walleye's existence at that time. Nine purported blue walleyes captured in 1975, including a number of gravid females, were inconclusive as to their subspecific designation and failed to produce any viable offspring through artificial propagation. The last known blue walleyes, to any degree of certainty, were captured in about 1965 from both lakes Erie and Ontario. Subsequent, exhaustive efforts to find a relict population have been entirely unsuccessful. The loss of the blue walleye is, arguably, an extinction event on par with the loss of the passenger pigeon and the near-extirpation of the American bison. Where once the subspecies numbered in the millions, all are now gone.
Source: Wikipedia
Posts
