Sudden Sturgeon Die-Off Has Biologists Concerned

by Craig Garrett
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Close-Up Of Sturgeon Swimming In Aquarium - stock photo

The sudden death of 11 endangered white sturgeons has left biologists shocked and scrambling to save a species on the brink of extinction. In September, Nikolaus Gantner and two colleagues were out on a jet boat when they first spotted a spindly, armored carcass in the fast-flowing Nechako River. They bravely decided to investigate despite the strong currents. Later, they discovered the 10 other bodies floating in a river in western Canada, The Guardian reports.

White sturgeon, a species that has barely changed in the last 200 million years, are gentle apex predators that glide around a few of British Columbia’s rivers. They use barbels – whisker-like appendages on their snouts – to feel along the river bottom for prey. The fish have bodies covered by five bony plates called scutes, and they look like living fossils. The largest on record was 20 feet long. Another one believed to be 104 years old weighed a whopping 1,800 pounds.

Researchers admire the ancient fish

Gantner, a senior fisheries biologist with the British Columbia government admires the ancient sturgeon. “When you see a massive head appearing through the murky water and the eyes look at you, it’s just incredible to see this majestic animal alive,” Gantner explained. “And you gain respect for it, knowing that most fish we see are older than us.”

The large number of deaths in such a short timespan has been emotionally draining for Gantner and his co-workers. “I’m deeply saddened. These last couple of weeks, I feel like I’m going through grief,” he explained. Handling the dead fish is rough on the scientists. “I don’t think I felt like that from other fish that I’ve worked with.”

So far, the team hasn’t been able to find any clues as to why the fish are dying. There’s no sign of trauma or exposure to chemicals, disease, or anything caused by people. Steve McAdam is a biologist with the province’s ministry of land, water and resource stewardship. He notes that the damage to the fish appears to a specific area. “Whatever it is, it affects larger sturgeon, not other species. It’s constrained to a place in time and space. So that gives us some clues,” explained McAdam. “In a way, it’s easier to rule a bunch of stuff out than to rule some things in.”

The sturgeon die off remains a mystery

There are a few theories going around, one belief being that the higher water temperatures are the issue. But McAdam said in previous summers when it was just as hot, there wasn’t die-offs like this. “There’s no end to the ideas. There are some partial explanations, but we’re really trying to keep an open mind and not veer too far down one path,” he explained.

Even before the decline, white sturgeon were struggling.There used to be over 5,000 in the Nechako River but after a century, only 500 are left. The main reason for this decrease is because of something called “recruitment failure.” This occurs when there’s a lack of new fish being added into the population and it happened soon after a dam was put up on the Nechako River in 1957.

26 species of sturgeon are now endangered because they overfish and the environments they live in are deteriorating. Specifically, some beluga sturgeons are becoming victims for their roe which is known as caviar. Both Gantner and McAdam are hopeful that the deaths of these elephants will serve as a learning opportunity for biologists. By studying what might have happened, they can take steps to prevent it from happening again in the future.

Outsider.com