Probable Wisconsinan Glacial Refugia as a Determinant of Fish Species Status in Vermont

Richard Langdon*

*199 Vermont Rt. 12, Middlesex, VT 05602.

Northeastern Naturalist, Volume 31, Issue 2 (2024): 202–219

First published early online: 9 June 2024

Abstract
Little has been published on post-glacial migration corridors of fishes in New England during the Wisconsinan Glaciation. I present an updated review of current literature on the origin of fish species in Vermont, with the focus on the Connecticut River and Champlain–Richelieu–St. Lawrence River drainage networks. A more accurate picture of post-glacial migration routes can provide a basis for determining whether a species is native to Vermont. Vermont supports fishes from 2 main refugial groups: the species-rich western and the relatively species-poor eastern refugia. Eastern species are native throughout the state, while western species are native only to lower elevations of the the Champlain drainage. Vermont’s 80 native species far exceeds any other New England state due to the addition of 40 western species. Twenty-three species may have dispersed from both major refugial regions, 12 species dispersed only from the eastern refugia, 4 species are anadromous, and 1 is catadromous. Recently revised aging of ice retreat and subsequent waterbody formation linked to putative recolonization routes can clarify native status, particularly in Vermont, where many western refugial species share their eastern-most limits of their natural distributions. I propose probable origin status to native Vermont species with respect to major Vermont drainages.

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