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Delineation of sympatric morphotypes of lake trout in Lake Superior

Transactions of the American Fisheries Society

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Abstract

Three morphotypes of lake trout Salvelinus namaycush are recognized in Lake Superior: lean, siscowet, and humper. Absolute morphotype assignment can be difficult. We used a size-free, whole-body morphometric analysis (truss protocol) to determine whether differences in body shape existed among lake trout morphotypes. Our results showed discrimination where traditional morphometric characters and meristic measurements failed to detect differences. Principal components analysis revealed some separation of all three morphotypes based on head and caudal peduncle shape, but it also indicated considerable overlap in score values. Humper lake trout have smaller caudal peduncle widths to head length and depth characters than do lean or siscowet lake trout. Lean lake trout had larger head measures to caudal widths, whereas siscowet had higher caudal peduncle to head measures. Backward stepwise discriminant function analysis retained two head measures, three midbody measures, and four caudal peduncle measures; correct classification rates when using these variables were 83% for leans, 80% for siscowets, and 83% for humpers, which suggests the measures we used for initial classification were consistent. Although clear ecological reasons for these differences are not readily apparent, patterns in misclassification rates may be consistent with evolutionary hypotheses for lake trout within the Laurentian Great Lakes.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Delineation of sympatric morphotypes of lake trout in Lake Superior
Series title:
Transactions of the American Fisheries Society
Volume
130
Issue:
6
Year Published:
2001
Language:
English
Contributing office(s):
Great Lakes Science Center
Description:
p. 1233-1240
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1233
Last page:
1240
Number of Pages:
7