Life history variation among four lake trout morphs at Isle Royale, Lake Superior

Journal of Great Lakes Research
By: , and 



Life history traits were compared among four morphs of lake trout at Isle Royale, Lake Superior. Of 738 lake trout caught at Isle Royale, 701 were assigned to a morph (119 humpers, 160 leans, 85 redfins, and 337 siscowets) using a combination of statistical analysis of head and body shape and visual assignment. On average, redfins were longer (544 mm), heavier (1,481 g), heavier at length (Wr = 94), more buoyant, and older (22 years) than siscowets (519 mm; 1,221 g; 90; 19 years), leans (479 mm; 854 g; 82; 13 years), and humpers (443 mm; 697 g; 87; 17 years). On average, leans grew from a younger age at length = 0 and shorter length at age = 0, at a faster early growth rate to a longer asymptotic length than the other three morphs, while redfins grew at a slower instantaneous rate and humpers grew to a shorter asymptotic length than other morphs. On average, leans were longer (562 mm) and older (15 years) at 50% maturity than redfins (427 mm, 12 years), siscowets (401 mm, 11 years), or humpers (394 mm, 13 years). Life history parameters did not differ between males and females within each morph. We conclude that differences in life history attributes of lean, humper, redfin, and siscowet morphs of lake trout are consistent with differential habitat use in waters around Isle Royale, Lake Superior.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Life history variation among four lake trout morphs at Isle Royale, Lake Superior
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2015.12.011
Volume 42
Issue 2
Year Published 2016
Language English
Publisher International Association for Great Lakes Research
Contributing office(s) Great Lakes Science Center
Description 12 p.
First page 421
Last page 432
Country United States
State Michigan
Other Geospatial Isle Royale
Online Only (Y/N) N
Additional Online Files (Y/N) N
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