Downstream Migration and Multiple Dam Passage by Atlantic Salmon Smolts

Abstract

The purpose of this study was to investigate behavior and survival of radio-tagged wild and hatchery-reared landlocked Atlantic Salmon Salmo salar smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont. Among hatchery-reared smolts, those released early were more likely to initiate migration and did so after less delay than those released late. Once migration was initiated, however, the late-released hatchery smolts migrated at greater speeds. Throughout the river system, hatchery-reared fish performed similarly to wild fish. Dam passage rates varied between the three dams and was highest at the dam where unusually high spill levels occurred throughout the study period. Of the 50 fish that did migrate downstream, only 10% managed to reach the lake. Migration success was low despite the presence of bypass solutions, underscoring the need for evaluations of remedial measures; simply constructing a fishway is not synonymous with providing fish passage.

Received July 8, 2016; accepted April 29, 2017 Published online June 30, 2017

ACKNOWLEDGMENTS

We acknowledge Brian Chipman and Nicholas Staats for their contribution in planning and organizing the study and Elsa Goerig, Micah Kieffer, Madeleine Lyttle, Ryan Cross, and Jaime Masterson for assistance in the field. Daniel Nyqvist was financed by Fortum Generation AB (32%), Fortum Environmental Fund, through sales of ecolabeled Good Environmental Choice’ electricity (32%), the EU INTERREG project “Open migration routes for Lake Vänern salmon” through the County Board of Värmland (23%), and Karlstad University (13%). The U.S. Geological Survey, S. O. Conte Anadromous Fish Research Center, provided equipment and expertise, in particular assistance with telemetry deployments. The U.S. Fish and Wildlife Service Lake Champlain Fisheries Conservation Office provided additional equipment and captured wild smolts, and housing for researchers was provided by the Vermont Department of Fish and Wildlife. We also acknowledge Green Mountain Power and Burlington Electric Department for making their facilities available for our study and Eisenhower National Fish Hatchery for supplying hatchery fish, as well as interested and helpful personnel at these companies. We thank Michael O’Dea for running gill Na⁺,K⁺-ATPase samples and Amy Regish for thyroid hormone analysis. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The findings and conclusions in the article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. The study was performed with ethical permissions from the American Association for Laboratory Animal Science (09054).