Dispatches

Lesley Evans Ogden The Fraser River in British Columbia, Canada, is the world's largest salmon‐producing river. In late summer, millions of fish head upstream to spawn in tributaries and lakes. In June 2019, a landslide was discovered in a remote narrow section of the river. In a canyon near Big Bar, north of Lillooet, an entire cliff section slipped. Huge rock slabs fell into the river, constricting water within a previously calm stretch and creating a new 5‐meter‐high waterfall impenetrable to many fish. Now, members of a Unified Command team comprising 180 people from all levels of government – First Nations, federal, and provincial – are trying to get as many salmon as possible past the blockage. It's a huge multi‐disciplinary effort, involving experts in biology, engineering, hydrology, aviation, water transportation, and heavy machinery, some of whom are working beside a raging torrent at the base of a 125‐meter‐tall cliff. “It's a very challenging work environment with environmental, hydrological, and rockfall‐debris challenges and hazards”, says the response team's environmental unit leader, Michael Crowe (Department of Fisheries and Oceans). Hydraulic rams, airbags, chippers, drills, and low‐velocity explosives are being used to manipulate rocks and boulders at the water's edge, and to install fish ladders and passageways so that fish can navigate on their own. As of August 27, mitigation efforts have allowed 12,000 salmon to climb upstream independently, while over 44,000 salmon – mainly sockeye and Chinook – were transported upstream by helicopter. Landslides are not unprecedented on the Fraser, a geologically active waterway, so salmon have long faced such disturbances. “The problem today is [that the salmon] aren't as abundant or productive as they once were because of ongoing anthropogenic changes to their habitats and the ocean, so they're less likely to recover from these kinds of disturbances now”, says salmon biologist Will Atlas (Simon Fraser University; Burnaby, Canada). Many of the Upper Fraser's stocks, including coho, steelhead, and Chinook populations, are threatened with extinction, so this latest salmon setback could be a devastating blow if efforts to get large numbers past the slide fail. The site is in one of the most inaccessible parts of British Columbia's interior, with no roads nearby, exacerbating many of the challenges of mobilizing resources and materials. Transporting salmon past the landslide. Big Bar Unified Command; CC BY‐NC‐ND 2.0 Tom Oates JASON is a secretive and independent scientific group advising the US