Quantifying lost and inaccessible habitat for Pacific salmon in Canada’s Lower Fraser River

• DOI: 10.1002/ecs2.3646
• Publication Date: 2021-07-08T08:03:32Z
• Authors: Riley J. R. Finn; Lia Chalifour; Sarah E. Gergel; Scott G. Hinch; David C. Scott; Tara G. Martin
• Keywords: Stream Restoration

Abstract Loss of connectivity caused by anthropogenic barriers is a key threat for migratory freshwater species. The anadromous life history salmonids means that on streams can decrease the amount habitat available spawning and rearing. To set appropriate targets restoration, it important to know how different populations have been impacted in terms location extent historically has lost or become inaccessible. Using mapped predicted fish passage diking infrastructure, both floodplain linear stream remains accessible today was estimated 14 salmon Lower Fraser River, British Columbia, Canada’s most productive river. place these estimates within historical context, area using vegetation records from 1850s, were digital elevation model‐derived network. bolster areas where little mapping done, current barrier data used predict locations likely barriers. Accessibility poor across entire region with only 15% remaining accessible. Linear ranged accessibility 28% 99% based Inclusion revealed an additional 33 km potentially inaccessible modeled network located approximately 1700 length completely lost. Comparing density against assessed status insights useful understanding impact rearing guiding allocation restoration effort. Applying methods addressing missing data, such as unmapped barriers, essential estimating context. While much emphasis placed role marine conditions wild Pacific recovery, magnitude loss cannot be ignored suggests major driver observed declines.