Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

Improving the conservation status of Arctic grayling: combining laboratory, field and modeling techniques to support the agency-irrigator decision making process (#35)

Katey Plymesser 1 , Kevin Kappenman 2 , Matt Blank 1 , Nolan Platt 1 , Ben Triano 1 , McMahon Tom 1 , Cahoon Joel 1 , Zale Al 1 , Rice William 3
  1. Montana State University, Bozeman, MONTANA, United States
  2. US Fish and Wildlife Service, Bozeman, MT
  3. US Fish and Wildlife Service, Denver, CO

Recovering and improving the conservation status of Arctic grayling (Thymallus arcticus) populations is a United States Fish and Wildlife priority goal. While grayling are widespread in much of Canada and Alaska and in parts of Europe and Asia, they are a species of special conservation concern in Montana.  In 2006, a Candidate Conservation Agreement with Assurances program for the Big Hole River Watershed was established to facilitate conservation. There is concern that barriers, such as irrigation diversions, may limit the movement of grayling. The purpose of this study was to determine the passage efficacy of Denil fishways installed at irrigation diversions to provide passage for grayling in the Big Hole River Watershed.  We have implemented a tiered approach that combines laboratory studies (2015-2017) with field investigations (2017-2018) to evaluate passage efficacy.  A unique, multi-faceted technique for assessing landscape connectivity in the field will be presented along with lessons learned.  Direct and indirect assessments of fishways in the Big Hole River Watershed were completed in 2017-2018. Direct assessment involved passive integrated transponder (PIT) tags to directly monitor grayling movements at field installations.  Indirect assessments defined fish movement through a range of Denil flow conditions based on lab data, hydraulic models of the field sites, and characterization of seasonal hydrology.  We have developed a decision-support tool to identify effective and less effective fishways, identify and prioritize retrofitting of less effective fishways, and improve passage design criteria for grayling.