Why are young sturgeon disappearing from the Fraser River?

The number of juvenile sturgeon in the Lower Fraser has dropped by 71% in two decades. Scientists are trying to figure out why.

By Josh Kozelj | August 2, 2022 |5:00 am

Sarah Schreier loves a good puzzle.

It’s why she has dedicated a large part of her conservation career to figuring out why the number of white sturgeon in the Fraser River has plunged.

The new findings of a two-decade-long study show that the Lower Fraser’s population of juvenile sturgeon—a youth phase of the fish—has dropped by nearly 71% over the past 18 years.

Researchers like Schreier know there’s a problem. But finding out what to do about it is another matter.

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The findings

Sturgeon are a remarkable species.

They have been around since dinosaurs roamed the earth and can live for more than 100 years.

The local sturgeon are the last of its kind in the world to live without an intervention, like a hatchery, said Schreier, the executive director of the Fraser River Sturgeon Conservation Society.

“This species is special,” she said. “Being able to help see the recovery of a fish that’s so long-lived and hard-wired to survive is the ultimate [goal].”

The study recorded nearly 45,000 sturgeon (aged seven to 55) in 2020, a 25 per cent decrease from the program’s highest tally in 2006.

The new sturgeon study suggested that the number of adults (aged 23 to 55) in the river between Yale and Tsawwassen has increased gradually over the last two decades. However, with a higher rate of sturgeon who are able to reproduce, Schreier said there should be more juveniles in the river. There aren’t.

The number of juvenile sturgeon (aged 7 to 12) hovered around 10,000, a significant drop from the over 30,000 that was recorded in the early 2000’s.

“We’re trying to figure out where these fish are going? What’s happening to them?” she said.

A graph of the abundance estimate of sturgeon from 2000 to 2020. The green line shows a decline in young sturgeon. 📸 Fraser River Sturgeon Conservation Society

Without the stabilization of the juvenile population, the study suggests the number of adults will begin to decline within a couple years.

The figures will also serve as a baseline for those trying to help the species.

“If you’re going to figure out how to save a fish or species, you have to know where you’re starting from,” Schreier said.

The sturgeon history

Every spring, long before settlers colonized the Fraser Valley, sturgeon travelled to Sumas Lake to spawn.

Unlike salmon that would run in the spring, summer and early fall, sturgeon were a reliable year-round food source for the Stó:lō people.

“They were critical to supporting food sustainability because they were in the river year-round,” Stó:lō Tribal Council President Tyrone McNeil said.

“I remember my uncle telling me in late fall and even in early winter, they would set out sturgeon lines and check them every day. If they caught one, they ate. If they didn’t they went hungry.”

Historically, culturally, and spiritually, the Stó:lō people had a direct connection with sturgeon.

McNeil said a young lady offered herself to the river and was transformed into a sturgeon.

“She always wore a red pendant around her neck. If you ever catch a sturgeon and cut the head off, just below the neck, there is a piece of red flesh that is really different from the rest of the white flesh.”

When the community caught a sturgeon, it was under the condition that they could consume the meat, but return bones and anything uneaten back to the river. The woman would be turned back into a whole sturgeon, and when the community was hungry again she would feed them.

“It’s a direct human relation to our community,” McNeil said. “There’s a tremendous amount of cultural heritage and there’s a spiritual value to our relation with the sturgeon people.”

Stó:lō people also used sturgeon for the paper-like membrane, isinglass, located on the fish’s backbone and in its abdomen. When a sturgeon was caught and dried, the isinglass turned into a paste that the Stó:lō used to stiffen and strengthen bows, waterproof baskets and canoe bailers.

Sturgeon isinglass was manufactured throughout the mid-1900s, and became a trading item between the Semá:th and Hudson’s Bay Company—which used the “sturgeon glue” as a gelatin to preserve food and as a clarifying agent for alcoholic drinks.

But when settlers started to hunt for sturgeon in the late 1800s, the ancient fish couldn’t reproduce fast enough to sustain their populations.

Half a million kilograms of Fraser River sturgeon were harvested in 1897, and between 1892 and 1902, more than 3.4 million kilograms of sturgeon meat and caviar were sent to overseas markets. By the time a mysterious die-off of 34 adult sturgeons prompted the province to enact a moratorium on fishing sturgeon in BC in 1994, the annual sturgeon catch was as little as 5,000 kilograms.

Today, most of the sturgeon in BC are protected under the federal Species at Risk Act, and sturgeon in the Lower Fraser are currently described as ‘threatened’ by the Committee of the Status of Endangered Wildlife in Canada.

The steps to protect the species are vital, as the health of the sturgeon is also a marker on the health of species in the entire river.

“It’s a complex ecosystem in the Fraser,” Schreier said. “[Sturgeon are] connected to every other species in the river.’”

Factors impacting today’s sturgeon

Marvin Rosenau, an instructor in the Fish Wildlife and Recreation Program at BCIT who has been studying sturgeon for over 30 years, says there are a combination of factors that could explain the sturgeon’s declining populations.

Angling, gillnetting, gravel mining, jet boat travel in spawning areas, a lack of food, and sturgeon cannibalism are all potential causes.

“Something happened around 2002 or 2004 that caused this catastrophic [juvenile] collapse,” Rosenau said. “We’ve got some curious suspects, but I don’t think anyone can point out that ‘it’s this or that.’”

Before growing up to six metres in length, juvenile sturgeon are tiny. 📸 Province of British Columbia/Flickr

Although BCIT’s Rosenau believes there are a multitude of factors impacting the Fraser River sturgeon, he thinks there is likely to be one primary factor causing the decline. He’s just not sure which one.

“It might be jet boat traffic during the incubation period, it might be the collapse of salmon… There’s got to be one dominant reason why it collapsed so quickly.”

The decline could also be linked to troubles with other fish species.

As one of the Fraser’s apex predators, sturgeon sit at the top of the food chain. They eat everything from water bugs on the river floor to larger fish like salmon and oolichan. Impacts on salmon and oolichan populations in the Lower Fraser—two species that sturgeon feed on—may be a factor in the decline of juvenile sturgeon, Schreier said. UBC researchers uncovered in 2021 that salmon have lost 85% of historical habitat in the Lower Fraser River due to dikes, floodgates, and road culverts.

“If the sturgeon are having trouble, then we have to take a really close look at the other species and the ecosystem in the Fraser and the health of the Fraser,” she told The Current.

Guiding in the Fraser

Dean Werk started fishing when he was five-years-old. Born and raised in Chilliwack, fishing has always been a huge part of his life.

His grandfather owned a farm on the Vedder River for 47 years. Werk, who is part Métis and Cree, would spend countless hours fishing on the Fraser and Vedder River with his dad. So it shouldn’t come as a surprise that Werk would grow up to launch a guided fishing business, Great River Fishing Adventures, in 1988.

In the late 1980s, sturgeon guiding on the Fraser River was not common. Prior to that time, Werk said, the fish was primarily used for harvesting and commercial sale.

“I started in ‘88 and nobody would even buy a fishing trip off of me for sturgeon. I couldn’t even give one way.”

Dean Werk holds a juvenile sturgeon in the Fraser River. 📸 Great River Fishing Adventures

Today, recreational catch-and-release sturgeon fishing is a major tourism draw in the Fraser Valley, with thousands of fish caught each year. And although any fish caught must be returned to the river, some conservationists have warned that catch-and-release fishing places stress on sturgeon and harms their ability to reproduce.

But Fraser River anglers have also been a key part of conservation efforts to research sturgeon, with each fish caught being recorded and tagged. Over the course of the Sturgeon Conservation Society’s study, professional anglers, recreational fishers, and other volunteers tagged and sampled over 170,000 sturgeon in the river.

Anglers have pointed to other potential culprits for the declining numbers, including gillnetting in the Fraser River and logging and farming near Herrling Island.

As an industry that has only been around for roughly 30 years, Werk said there is still a lot of work that needs to be done to analyze why the juvenile sturgeon population is decreasing.

“We haven’t barely touched the surface to actually explore all reasonings, and until that time in which we have researched it enough, there should not be knee-jerk reactions made,” Werk said.

“In my opinion, there has to be a lot more work done to understand to help these fish in the future.”

Werk points to a recent provincial juvenile sturgeon tagging program that shows the species may not be in a sharp decline.

Two years ago, the Habitat Conservation Trust Foundation, funded a program that aims to tag juveniles, give habitat assessments, and research historical bycatch information. Sturgeon guides in the Fraser River have tagged about 5,000 juveniles since the program launched.

Unlike in the past, where guides were preoccupied with catching larger fish, Werk said the fishing industry has gotten better at creating specific equipment like small hooks to track juvenile sturgeon.

“We identified that there was possibly a hole, like a blackout, in the ability to see juvenile sturgeon,” Werk said. “We wanted to catch big fish, so we wanted to set up our fishing gear, our baits, and where we fished to target large fish for clients from around the world.”

Anglers like Werk are using smaller hooks to catch, tag, and release juvenile sturgeon. 📸 Great River Fishing Adventures

Before the program is over, Werk is hoping to sample 10,000 juveniles.

“Now we’re targeting [juveniles] with smaller hooks, we’re using smaller baits, going in different types of waters,” he said. “We’re going out searching from the ocean, 350 miles of river, sampling juveniles.”

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What to do next?

Despite the lack of a simple explanation for the sturgeon’s decline, there are potential solutions to combat the regression, the society’s report says.

The society argues that protecting juvenile rearing habitats and decreasing the number of sturgeon caught by recreational fishing can help the fish recover.

They also call for protections for back channels of the Fraser River where sturgeon prey live.

Rosenau agrees that sturgeon need a larger amount of food to be able to reproduce.

In concert with protecting food supply, Rosenau adds that there should be no disruption to side channels—especially during sturgeon’s spawning season from May to July.

“Just as freshet is coming along, May, June, into July, those babies are sitting there on the rocks,” Rosenau said. When jet boats pass, their wakes can wash the young sturgeon away.

McNeil says all conservation groups should work together to manage the river.

He said a management plan to protect the sturgeon should be built around the precautionary principle.

He said habitat loss, recreational fishing, and warming waters are all factors impacting the fish. Without evidence pinpointing which one is the main culprit, he said any plan should assume that all potential causes of sturgeon decline are to blame and attempt to reduce each one.

“I believe really strongly that effective strategy will allow the sturgeon population to grow significantly,” McNeil said. “But we all have to be on the same page on it, and we need to start now. Not 10 years or 20 years from now.”

Similarly, Werk said the health of the fish is his first priority, and protection for sturgeon rearing-habitats should come from provincial and federal levels of government.

“These fish have no voice, and I would like to be the messenger and the voice for these fish.”

Although the Fraser River Sturgeon Conservation Society doesn’t have the power to enact legislative changes, Schreier hopes the study will provide a blueprint for other organizations to help ensure the health of the white sturgeon moving into the future.

“This effort to recover this species is the ultimate puzzle.”

Josh Kozelj

Intern at Fraser Valley Current

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