Drought caused by climate change in parts of Canada lead to apocalyptic scenes as thousands of dead salmon litter river banks.

More than 65,000 salmon have died before they could spawn in just one Canadian stream. The die-off of two species, mostly pink and some chum salmon, hints at a potentially devastating season for the fish, local people, and the wider ecosystem throughout the region.

Researchers from Simon Fraser University came upon the mass fish calamity in the Neekas river in British Columbia’s remote Central Coast on September 29. The waterway is near the community of Bella Bella, within Indigenous Heiltsuk Nation Territory. The full video shows a 360 degree view of the carnage.

In a typical year’s fall, adult pink and chum salmon migrate from the Pacific Ocean upstream into the waterways where they were born to spawn. After laying their eggs, the fish do usually die—nourishing other wildlife, waterways, and the forest on their way out. But nearly all of the fish found in Neekas died before they could reproduce, said Allison Dennert, a PhD candidate at Simon Fraser and one of the researchers to first come upon the scene. “To see that many who hadn’t had the opportunity to spawn yet was incredibly heartbreaking,” she told Earther by phone.

Dennert is accustomed to seeing dead salmon, “but this level of death is certainly unprecedented to witness,” she explained. Dennert and her colleagues smelled the stream far before they saw it. And, once in the thick of the fish corpses, the odor was acrid. The researchers had to cover their faces to stand near the stream. “It was burning our noses and eyes,” Dennert said.

Drought and a late season heat wave have swept through B.C. and other parts of the Pacific Northwest this fall. Simultaneously, there are record high temperatures and record low September and October rainfalls. As a result, many waterways are running low, and some are drying up entirely. The die-off recorded in Neekas is likely just one of many happening on the landscape, said Will Atlas, a salmon watershed scientist at the nonprofit Wild Salmon Center, in a phone call with Earther. “There are lots of creeks that have no water right now,” he said.

Atlas expects that this fall’s die-off will take at least five to six generations (where each generation is two years) for the pink salmon population to recover, and that’s assuming that there isn’t another bad year in that time period. In 2010 and in 2018, amid other droughts, pink salmon in the same area also experienced significant losses, he said. In total, the Central Coast’s population has fallen by about 66%, comparing the past two decades, according to data from the Pacific Salmon Foundation.

The fish face a myriad of threats, including aquaculture, pollution, and overfishing. But climate change is likely the biggest factor in their decline, said Atlas. Previous research has found that human-caused climate change is increasing the instance and intensity of heatwaves in British Columbia. And more extreme droughts are becoming increasingly likely.

Die-offs and droughts do occur naturally, said Atlas, and salmon are adapted to manage some level of disturbance. But “these types of events are getting more frequent, and they’re very unpredictable. Salmon, as much as they’ve evolved to deal with it,” can’t keep up, he explained. Which means their populations suffer, but so too does everything else. The fish are “foundational to the foodweb,” said Atlas. Bears, wolves, eagles, and other carnivores take live salmon from streams and spread their scraps around, benefitting scavengers, plants, and other wildlife. The whole system depends on the fish and their lifecycle to propel it from one year to the next. Plus, the rotting fish have depleted most of the oxygen in the Neekas, leaving the creek inhospitable to other freshwater life for now, including juvenile Coho salmon that hatched earlier this year.

Dennert said the only living fish her and her colleagues found were clustered under a waterfall, where the churned-up water has enough dissolved air in it to support them. But under the falls, there was nowhere for the salmon to lay their eggs. Atlas said he thought there could be “complete spawn failure” for the river.

Then, there’s the people. Salmon are one of the most widely eaten fish in the world. In the U.S., people consume more salmon than any other fish, according to NOAA data. The global salmon industry was valued at more than $208.8 billion in 2021, according to a Research and Markets report. And, for those who live in British Columbia and other parts of the Pacific Northwest – particularly Indigenous communities – the fish are a staple food, central to local culture.

Salmon are drivers for absolutely everything locally,” William Housty, conservation manager for the Heiltsuk First Nation in Bella Bella, said in a phone call with Earther. He said this year’s die-off will have long-lasting impacts for everyone in his community who relies on salmon for food and economic opportunities. According to Housty, drought is the underlying problem, but it was actually a small stint of rain a couple of weeks ago and a tidal event that likely drew the salmon upstream. Even though conditions weren’t good, the fish rely on environmental cues to dictate their movements. After the small series of showers, the pinks went upriver and quickly ran out of water.

Before the mass mortality event, Housty had high hopes for the Neekas system. He knew there was a big population of pink salmon ready to come upstream. And “to know that they all died is devastating.”
Dennert echoed that sentiment. “These are the fish that made it,” she said. After facing warming unhealthy oceans, the threat of fishing and predation, and the perilous journey back to where they hatched—these salmon were the champions. But then they hit a barrier they couldn’t overcome.

In a small silver lining, Housty said that maybe all the carcasses washed downstream into the estuary will be good for the Dungeness crabs. “But it’s really unfortunate everything else is missing out.”

Original source: https://gizmodo.com