Relationships among fluvial and adfluvial brook trout (Salvelinus fontinalis) in a Lake Superior tributary revealed using genomic and passive integrated transponder data

Document Type

Article

Publication Date

1-1-2026

Abstract

In the Lake Superior basin, brook trout ( Salvelinus fontinalis ) that exhibit an endemic adfluvial life history known as coasters have been the focus of considerable rehabilitation efforts given historical basin-wide declines in abundance. A recent study of brook trout in the Pilgrim River (Michigan, USA) employed passive integrated transponder (PIT) tags and documented outmigrating individuals, indicating a potential remnant coaster population. Our objective was to evaluate combined information on life history and genetic diversity for adfluvial and fluvial brook trout in the Pilgrim River using insights from PIT tag data and newly generated genomic data. We used restriction site-associated DNA sequencing (RADseq) to survey 4906 single nucleotide polymorphisms (SNPs) in 120 wild-caught brook trout where movement status was independently determined for a subset of individuals using PIT tagging. Results from multivariate analyses were consistent with the presence of a single population, where genetic population structure did not appear to be influenced by movement status. An inability to distinguish coaster brook trout and their stream resident counterparts based on our RADseq dataset suggests a lack of reproductive isolation between life history forms, but a more thorough comparison will benefit from higher-density genetic markers. Information on population genetic relationships is especially important for rivers that harbor extant coaster populations, and our results offer valuable baseline information for conserving genetic diversity in brook trout from the Pilgrim River. Further studies are necessary to clarify any molecular or other factors influencing life history in Lake Superior basin brook trout and are urgently needed to inform coaster restoration.

Publication Title

Journal of Great Lakes Research

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