Alberta’s threatened Lake Sturgeon population better understood thanks to volunteers

The presence of Lake Sturgeon in the Saskatchewan River system has become somewhat of a myth amongst anglers in Alberta. Despite their immense size, these ghost-like fish can be very challenging to catch. Anglers across Alberta seek out this unique and ancient fish for its size and incredible fighting power. Should they manage to hook one, it will likely be the largest fish they ever catch. 

An ancient species 

Lake Sturgeon are Alberta’s largest fish and one of the oldest living fish species on the planet. They can grow up to 1.7 meters in length and weigh up to 108 lbs (49 kg) in Alberta, however the largest Lake Sturgeon documented in Canada weighed nearly four times that (407 lbs/185 kg). This ancient species’ evolutionary history dates back to when dinosaurs roamed the Earth, showing their incredible ability to adapt to changing environments across vast periods of time in Canada’s lakes and rivers. 

Unlike most freshwater fish in North America, sturgeon lack traditional scales. Instead, a cartilaginous skeleton shields their body with five rows of sharp, bony scales that act as armour. Using whisker-like barbells in front of their mouth, sturgeon detect their prey, such as aquatic invertebrates and small fish, in the dark, turbid waters. 

Lake Sturgeon, one of eight species of sturgeon found across North America, can be found from the southern Hudson Bay drainage to as far south as the lower Mississippi drainage and Alabama. In Alberta and Saskatchewan, Lake Sturgeon can be found in the North Saskatchewan and South Saskatchewan Rivers as well as further east in Canada throughout much of Manitoba, Ontario and western Quebec. Despite their name, Lake Sturgeon in Alberta are almost exclusively found in large rivers and are the only sturgeon species in Canada that spend their entire lifecycle in freshwater environments.

While many spend long periods in overwintering and feeding habitats, some individual Lake Sturgeon showcase remarkable migrations. In 2010, researchers captured and tagged one upstream of Edmonton that was subsequently recaptured the following spring downstream, at the confluence of the North Saskatchewan and South Saskatchewan Rivers. A month later, the same fish was once again detected upstream of Edmonton; a round trip of approximately 1,400 kms. This type of movement is unusual for Lake Sturgeon whose yearly movements more typically occur within a 70 kilometre stretch of river.

Lake Sturgeon are a long-lived species with typical lifespans of 50 to 80 years, though some have been documented living up to approximately 150 years. The long lifespan of sturgeon has sparked a growing recognition among researchers of what could be learned about past and present ecosystem conditions. This interest spawned increased research beginning in the 1990s, including work to garner a better understanding of the size and health of sturgeon populations in Alberta. 

Conservation challenges

Overharvesting, habitat fragmentation and habitat degradation have threatened Lake Sturgeon since the mid-1800s and led to population declines across its Canadian range. Overharvesting initially reduced Lake Sturgeon’s distribution. In 1967, the Gardiner Dam in Saskatchewan separated the population in the North Saskatchewan River from those in the South Saskatchewan River which, in addition to very poor water quality in the late 1950s and 1960s, further impacted western Lake Sturgeon populations.

Today, Lake Sturgeon populations are of concern across Canada. In 2007, they were listed as Threatened in Alberta under the Wildlife Act due to the relatively small number of reproducing adults and the species’ restricted distribution in the province. In 2008, a recovery team formed and developed the Lake Sturgeon Recovery Plan with the goal “to enhance and protect self-sustaining populations of Lake Sturgeon within its current range in the North Saskatchewan and South Saskatchewan River drainages of Alberta”. Despite ongoing efforts, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed the Saskatchewan-Nelson River populations found in Alberta as Endangered in 2017. Understanding the abundance, survival and movement of Lake Sturgeon populations in the Saskatchewan River system is essential to inform this recovery plan and ongoing conservation efforts.

Tracking sturgeon

Have you ever wondered how scientists estimate fish populations? Alberta has been monitoring Lake Sturgeon populations since 1968 in the South Saskatchewan River and since 1990 in the North Saskatchewan River to help inform species management activities. In many species, including fish, counting every individual is not possible. Because of this, scientists use a survey method known as Capture-Mark-Recapture (CMR) where a portion of the population is captured, marked, then released back into their habitat (Figure 1). At a later date, another portion of the population is captured, and the number of marked individuals is counted within this new sample, while unmarked individuals continue to be marked with unique identifiers. In small populations, recapturing marked individuals is more likely compared to large populations. This data is then fed into CMR models that generate estimates of population size, survival, and recruitment.

In the past, anglers would capture sturgeon and mark them with an external tag fixed to the fish. These were cost efficient and easy to use, however, an estimated 15% to 22% of external tags fall off the fish. This made estimating population size and individual survival much more challenging. 

Today, technology has improved and Passive Integrated Transponder (PIT) tags are commonly used to individually mark and track fish. A PIT tag, a pill-shaped glass cylinder containing a radio transponder, only slightly larger than a typical grain of rice, is inserted into the belly or musculature of the fish by trained technicians. The PIT tag acts as a unique barcode that can be scanned by a special receiver for the remainder of the fish’s life. This technology also enables scientists to detect and identify fish passing by in the river with the receiver, without needing to capture them. This is the same microchip technology used for marking and identification of pet animals. The near permanence of these tags allows scientists to accurately track sturgeon while leaving the fish unharmed.

Volunteer Angler Program

Monitoring Lake Sturgeon populations is an incredible feat and Government of Alberta fisheries biologists don’t do it on their own. Citizen Science is a critical part of Alberta’s efforts to estimate Lake Sturgeon populations in the North and South Saskatchewan Rivers.

“For over 30 years, anglers have collected information that has been incredibly useful to our conservation efforts,” said Dr. Stephen Spencer, Senior Fisheries Biologist with Alberta Environment and Protected Areas (EPA). Anglers provide information on the number of sturgeon caught, river conditions, and changes they’ve witnessed to their habitat.

“These volunteers are stewards of the river and they are collecting high quality data,” said Stephen.

Jeff Krukowski has been fishing the North Saskatchewan River in search of these elusive fish for more than 20 years. Jeff began angling sturgeon in 1998 and learned about the volunteer angler program from a fellow angler. Since 2003, Jeff has been a dedicated volunteer and an integral part of the program, tracking every fish he catches.

“The best part is the information and knowledge exchange. Volunteers get to share their experiences on the water with the biologists, and in turn get updates on the population models developed. It’s a really cool collaboration.”

Jeff spends approximately 300 hours a year fishing on the North Saskatchewan River and has been instrumental in supporting sturgeon research and conservation efforts. Today, approximately six dedicated volunteers, trained by EPA fisheries biologists, submit data to the program. This small but mighty team of volunteers submits hundreds of Lake Sturgeon captures each summer.

Training provided to volunteers ensures these anglers are equipped with the skills and knowledge to properly handle Lake Sturgeon, ensuring fish are brought in and released quickly, and they remain in the water as much as possible. In Alberta and across Canada, angling for Lake Sturgeon is catch and release only.

A positive direction

Recent collaborative research by a team of biologists and mathematicians from the Government of Alberta, the University of Alberta and the University of Victoria sought to better understand population dynamics of Alberta’s Lake Sturgeon population in the Saskatchewan River system. 

With funding from EPA’s Office of the Chief Scientist, the team used data from the Volunteer Angler Program and innovative modelling approaches to estimate population size, survival, and recruitment, with promising results. Although work is ongoing, new models suggest sturgeon populations in the North Saskatchewan River have been stable since 2012, with nearly 10 times more individuals than previously estimated in the 1990s. Analysis of the data for the South Saskatchewan Lake Sturgeon population will be underway in the near future.

While these results are positive, researchers also noted that local annual survival rates in the North Saskatchewan River appear to be low, suggesting that sturgeon could be migrating from downstream sections of the river outside of Alberta to help stabilize the population. Researchers are continuing to work on refining these models to better account for data-related challenges such as external tag loss (prior to PIT tag use) and highlighting the importance of consistent, long-term monitoring. 

While there’s more work to do to better understand Lake Sturgeon population dynamics, the positive results from this project indicate that the Lake Sturgeon population in Alberta’s North Saskatchewan River is larger than previously estimated and is likely stable at present.

Additional resources

• General Information about Lake Sturgeon
• Alberta Lake Sturgeon recovery plan 2011-2016
• Lake Sturgeon Fish Sustainability Index (FSI)
• Lake Sturgeon are catch and release only, as listed in the Alberta sportfishing regulations. For handling tips, see the My Wild Alberta website at: Lake Sturgeon handling practices