ASSESSMENT OF ARCTIC GRAYLING RE-INTRODUCTION POTENTIAL IN THE BIG MANISTEE RIVER, MICHIGAN.

• Main Author: Goble, Cameron
• Format: Text
• Language: unknown
• Published: Digital Commons @ Michigan Tech 2017
• Subjects: Arctic Grayling; Native species restoration; stream ecology; fisheries; Terrestrial and Aquatic Ecology; Arctic; Canada; Little River; Arctic grayling; Thymallus arcticus; Alaska
• Online Access: https://digitalcommons.mtu.edu/etdr/336; https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1468&context=etdr

Arctic Grayling Thymallus arcticus were once the dominant fluvial salmonid species in Michigan’s Lower Peninsula. By the late 19th century most populations in the State had experienced drastic declines and by 1936 the species was declared extinct in Michigan. Beginning in 2011 the Little River Band of Ottawa Indians and Michigan Technological University partnered on research to determine the feasibility of re-establishing the species in the Big Manistee River watershed which was home to one of the last Arctic Grayling populations in the Lower Peninsula. The objectives of this research were to: A) assess abiotic habitat suitability for Arctic Grayling, B) identify potential biotic interactions that could impact Arctic Grayling re-introduction success, C) assess food availability and bioenergetic capacity of eight Big Manistee River tributaries, and D) model population viability and extinction sensitivities of a potential re-introduced Arctic Grayling population. Results from this study indicate that suitable biotic conditions for Arctic Grayling are available in all of the eight tributaries included in this study. Brook and Brown Trout currently occupy all of the potential re-introduction tributaries and densities of Brown Trout > 0.10/m2 should be considered a potentially limiting factor in determining overall site suitability (Chapter 2). A bioenergetic assessment indicates that 59% of the study reaches exhibit positive Net Energy Intake (NEI) for drift-feeding salmonids indicating that they are likely suitable re-introduction areas. No statistically significant relationship was found between invertebrate densities or NEI and the densities of salmonid species currently occupying these habitats indicating that food availability is not a limiting factor for salmonids in the Big Manistee River system (Chapter 3). Population viability analysis indicates that it is possible to establish a viable Arctic Grayling population in the middle portion of the Big Manistee River watershed studied. Sensitivity analyses suggest that Arctic Grayling populations in the southern portion of their range (i.e. Michigan and Montana) are most sensitive to factors influencing reproductive output while northern populations (Canada and Alaska) are most sensitive to factors affecting adult survival (Chapter 4) Overall, the combined findings from this research suggest that conditions are favorable for Arctic Grayling re-established in the Big Manistee River watershed.