Abstract 298 – Determining the importance of kokanee salmon to grizzly bears in central British Columbia

Shelley Marshall, Dexter Hodder, Matt Scheideman, Kara MacAulay, Clayton Lamb,
David Breault, Adrian Batho, Morgan Anderson

Conservation and stewardship of wildlife requires an understanding of how landscape and
climate change influence the interactions between wildlife and their environment. Grizzly bears
(Ursus arctos) in central B.C. rely primarily on plant-based foods and terrestrial meat sources to
meet their energetic requirements though are known to sometimes consume kokanee salmon.
Abnormal weather patterns can vary food availability through late spring green-up, berry crop
failures, or droughts constraining fish movement. Climate and landscape change can accentuate
effects on temperatures, water flow, and precipitation. Given the effects of landscape and
climate change on fish spawning, managers must understand if kokanee are important to these
grizzly bears to consider appropriate actions to maintain this food source. Through five years of
non-invasive hair sampling along three kokanee streams, we quantified the use of kokanee by
grizzly bears. As predicted, spawning kokanee were an important food source in our study area.
We detected 89 individual grizzly bears at these streams which reside in two of the lowest
density population units of grizzly bears in B.C. Isotope and mercury analysis demonstrated the
importance of this kokanee resource given its relatively short availability (~30 days). Mark-
recapture analysis found a positive relationship between berry abundance and bear use of the
kokanee streams. This may be an example of macronutrient optimization as the habitat in and
around these kokanee spawning streams was a mosaic of riparian retention and cutblocks
supporting both berry production and kokanee spawning habitat. We recommend protection
measures to maintain the integrity of the spawning grounds, identification of nearby kokanee
spawning streams and similar protections considered, and continued monitoring to provide
additional insights into the importance of kokanee beyond the variability in conditions
(drought, fires, high water) captured during this study.