Ciscoes of the Laurentian Great Lakes and Lake Nipigon

A new Great Lakes Fishery Commission publication describes in detail the past and present day ciscoes of the Great Lakes and Lake Nipigon.

Extant ciscoes of the Laurentian Great Lakes are shown. Image: Andrew Muir (Great Lakes Fishery Commission).

Extant ciscoes of the Laurentian Great Lakes are shown. Image: Andrew Muir (Great Lakes Fishery Commission).

“Ciscoes of the Laurentian Great Lakes and Lake Nipigon” which was recently published by the Great Lakes Fishery Commission contains information on the taxonomy, geographic distribution, ecology, and status of cisco species or, more properly, forms. Of the seven currently recognized forms, which include Cisco (Coregonus artedi), Bloater (C. hoyi), Deepwater Cisco (C. johannae), Kiyi (C. kiyi), Blackfin Cisco (C. nigripinnis), Shortnose Cisco (C. reighardi), and Shortjaw Cisco (C. zenithicus), the Deepwater and Shortnose Ciscoes are extinct. In addition, Longjaw Cisco (C. alpenae), had been synonymized with the shortjaw cisco, and although extinct, was recognized as valid, making now a total of eight major forms.

Each of the Great Lakes and Lake Nipigon before settlement supported a complex of cisco forms that varied among lakes and that were extremely vulnerable to overfishing and introduced species. To varying degrees within each lake, the fishery induced a successional process, first by removing the larger forms, which facilitated their replacement by smaller forms, and, second, by disturbing the reproductive barriers that presumably had allowed what were recently evolved forms to differentiate.

“Ciscoes of the Laurentian Great Lakes and Lake Nipigon”  was published because coregonines are taxonomically problematic owing to a wide array of phenotypic diversity often resulting in greater within- than among-lakes variation. The coregonine problem has continued to be of considerable interest in the Great Lakes region. The lack of a suitable field guide to the ciscoes of the Great Lakes and Lake Nipigon has impeded the detection of ecologically significant units, especially now that extirpations and hybridizations have occurred within the species lakes. Ecological significant units include those populations having exceptional gill raker counts, unique depth distributions, distinctive reproductive behaviors, or critical functional roles. This will make field and laboratory identification of ciscoes less onerous and thereby contribute to improved understanding and conservation.

Inclusion of the extirpated and extinct forms in this publication allows a look at the diversity of each lake’s species make up at the time of settlement. The inclusion of extirpated and extinct forms also acknowledges that individuals resembling any of these forms could appear, as was recently documented for two forms. Lake Superior has retained all four of its original forms, which include Cisco, Bloater, Kiyi, and Shortjaw Cisco. Seven forms have been lost in Lake Huron leaving only Cisco and an introgressed deepwater form that exists as a hybrid swarm. Of Lake Michigan’s eight original forms only Cisco and Bloater still exist. Both of Lake Erie’s original forms have been lost, and only Cisco, exists in Lake Ontario.

Funding for this project was provided by the Great Lakes Fishery Commission, Great Lakes Fishery Trust, U.S. Geological Survey, Fisheries and Oceans Canada, and the Sea Grants of Michigan, New York, Minnesota, and Wisconsin. The layout of this publication owes to Todd Marsee of Michigan Sea Grant, who brought together artwork, graphics, and text in a visually appealing and reader-friendly design that captures well the grandness of the Great Lakes and its foremost endemic fishes—the ciscoes.

Michigan Sea Grant helps to foster economic growth and protect Michigan’s coastal, Great Lakes resources through education, research and outreach. A collaborative effort of the University of Michigan and Michigan State University and its MSU Extension, Michigan Sea Grant is part of the NOAA-National Sea Grant network of 33 university-based programs.

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