Morphological and Ecological Differences Between Shallow- and Deep-water Lake Trout in Lake Mistassini, Quebec

January 1, 2007 - Mara S. Zimmerman; Charles C. Krueger; Randy L. Eshenroder

Journal or Book Title: Journal of Great Lakes Research

Keywords: Adaptation; buoyancy regulation; humper; lean; phenotypic diversity; siscowet

Volume/Issue: 33

Page Number(s): 156-169

Year Published: 2007

Lake trout (Salvelinus namaycush) in Lake Mistassini, Quebec, were investigated to determine whether they resembled the lean and siscowet morphotypes of Lake Superior and Great Slave Lake. Lake trout caught in deep water were predicted to resemble the siscowet morphotype and to be better adapted for vertical migration (i.e., low percent buoyancy) than those caught in shallow water. The research objectives were to 1) identify groups based on shape, and 2) determine whether shape was associated with other morphological traits (fin length, buoyancy, color), ecology (habitat depth, diet), and life history (size at adulthood). Eighty-five lake trout were collected from three depth zones. At least two phenotypes exist in Lake Mistassini. A shallow-water form (< 50-m depth), identified by its streamlined shape, was dark in color and high in percent buoyancy. A deep-water form (> 50-m depth), identified by a deep anterior-body profile, was light in color and lower in percent buoyancy than the shallow-water form. Absolute buoyancies were relatively high in both forms; therefore, the deep-water form did not appear well-adapted for vertical migration. Opossum shrimp (Mysis relicta) were more frequent and abundant in stomachs of deep-bodied trout. All deep-bodied trout (minimum 32-cm SL) had reached adulthood, whereas immature streamlined individuals were as long as 49 cm in SL. The deep-bodied form resembled humper lake trout, a lesser-known third morphotype from Lake Superior. A humper-like morphotype in Lake Mistassini, and the apparent absence of a siscowet-like morphotype, challenges the previously- held hypothesis that humpers resulted from an introgression of leans and siscowets.

Type of Publication: Journal Article

Publisher: International Association for Great Lakes Research

Authors

You Might Also Be Interested In

Accessibility Questions:

For questions about accessibility and/or if you need additional accommodations for a specific document, please send an email to ANR Communications & Marketing at anrcommunications@anr.msu.edu.

Tag List
  • adaptation,
  • buoyancy regulation,
  • center for systems integration and sustainability,
  • humper,
  • lean,
  • phenotypic diversity,
  • siscowet
Michigan State University
  • Spartans Will.
  • © Michigan State University

MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential.

Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.

The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707.

We comply with the Federal Trade Commission 1998 Children’s Online Privacy Protection Act (COPPA).