Symposium Summary: Barrier Removal in the 21st Century: Context, Generalities, and Potential Trade-Offs

Coho salmon trying to jump over a partial barrier in British Columbia, Canada. Credit: Jonathan Moore.

Coho salmon trying to jump over a partial barrier in British Columbia, Canada. Credit: Jonathan Moore.

Communities are working together to remove barriers and bring back fish, from the Penobscot to the Elwha to the Salmon River. Dams fundamentally fracture the natural connectivity of rivers, blocking natural movements of fish and sediment. There are over 2 million dams in the United States, and 80% of them are more than 50 years old. This symposium gathered scientists and practitioners from diverse regions to share their experience and expertise on barrier removal. Despite the diverse backgrounds of the speakers, consistent themes emerged from the symposium. First, barrier removal can rapidly restore migratory fish and river processes—speakers shared stunning stories of fish populations rapidly spreading and thriving after barrier removals. However, barrier removal can have trade-offs; dams can provide benefits of energy and water, block invasive species, provide heritage value, or generate scientific data such as on water flows. Thus, some barrier removals are win-win opportunities for people and rivers, but other barriers are muddier and their removal may lead to undesired consequences. Prioritization of barrier removal, whether it is strategic or organic, can consider these trade-offs. Dam science can inform dam removal.   —Jonathan W. Moore, Simon Fraser University, [email protected] Read the symposium abstracts here.