Contrasting Life History Characteristics Between Riverine and Lacustrine Anadromous Arctic Char (Salvelinus alpinus) in the Western Canadian Arctic

ABSTRACT Freshwater habitat characteristics are known to affect life history traits of migratory salmonids. Although the life cycle of the anadromous form of Arctic char (Salvelinus alpinus) is typically associated with lakes, there is a small number of anadromous populations in North America that spawn, rear, and overwinter exclusively in rivers. The life history traits of these relatively understudied populations and how they differ from lacustrine Arctic char are poorly documented. We characterized life history tradeoffs expressed by anadromous Arctic char originating from a riverine (Hornaday River) and a relatively nearby lacustrine system (Tatik Lake of the Kuujjua River) in the western Canadian Arctic using a 10‐year dataset. The riverine population attained smaller average size (600 mm vs. 628 mm, fork length) and mean age (7.7 vs. 10.6 years), had a lower longevity (14 vs. 26 years), and expressed a 44% higher growth rate resulting in larger size‐at‐age prior to reaching modeled length asymptote (700 vs. 754 mm). Furthermore, the riverine population had a younger modal age‐at‐maturity (approximately 6–7 vs. 11–13 years) and mean age‐at‐first migration (4.1 vs. 6.4 years), and a higher natural mortality rate (0.31 vs. 0.21 per year). Our results broaden knowledge on the spectrum of life history strategies exhibited by anadromous Arctic char and underscore how freshwater habitat influences vital rates and life history tradeoffs, which have implications for conservation and sustainable harvest (e.g., maximum sustainable yield) of salmonids.