Turning the tide for the bigmouth buffalo fish

In 2009, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) gave them this designation in Saskatchewan’s Qu’Appelle River system. This was followed by a listing under the federal Species at Risk Act (SARA), which offers a variety of legal protections under Canadian law.

That is why they have been the focus of a University of Saskatchewan (USask) research team for the past three summers. Led by USask graduate student Reid Bryshun, a group of researchers have been exploring Buffalo Pound Lake and gathering information about the bigmouth buffalo fish and its rival, the common carp fish (Cyprinus carpio).

The bigmouth buffalo is Saskatchewan’s largest sucker fish — it can grow to be one metre long and can weigh up to 25 kilograms. While drought and parasites may contribute to its population decline, the larger influences are misidentification and water management practices.

“Bigmouth buffalo fish have a look-alike in the common carp,” says Dr. Maud Ferrari, an associate professor at the Western College of Veterinary Medicine (WCVM) and an international leader in aquatic and behavioural ecology. Ferrari explains that people who sport-fish are at risk of catching bigmouth buffalo when they believe they are handling common carp.

In addition to having a similar appearance to the common carp, an invasive species, bigmouth buffalo fish are in competition with them. Common carp are abundant in the Qu’Appelle River system and could be out-competing the bigmouth buffalo.

“They share a similar diet and habitat,” says Ferrari. “But like most invasive species, [common] carp are more flexible — they have a more diverse diet, grow faster and can spawn in a wider range of habitats.”

The USask researchers have been assigned the task of studying the link between these two species. Bryshun and his team have been working under the supervision of Ferrari and Dr. Mike Pollock, an adjunct faculty member in the WCVM’s Department of Veterinary Biomedical Sciences.

By tagging and tracking bigmouth buffalo fish and common carp, they aim to determine the spatial overlap and competition between the two species. The researchers have also gathered information that will help them to determine the age demographic of the bigmouth buffalo — important information that can be used to link spawning success to flow rate of the water in Buffalo Pound Lake by year.

“Our management practices favour some species over others,” explains Ferrari. “With dams, we control the flow. And if we don’t flood the vegetation at the correct time of year … [we] reduce the available area for [bigmouth buffalo] spawning. We want to determine if we can link spawning success to a year that had either high or low flows.”

Buffalo Pound Lake is part of the Qu’Appelle River system, a unique habitat in Saskatchewan, that contains approximately 75 per cent of Saskatchewan’s fish species, making it the aquatic system with the highest level of diversity in the province.

It is also the only location in Saskatchewan that contains bigmouth buffalo fish. This body of water, which is intensively fished, is also used for recreation, flood and drought protection, and irrigation. In addition, it supplies water to many communities. In recent years, there’s been concern about the impact of people on the fish populations in the Qu’Appelle River system — particularly the human impact on the bigmouth buffalo fish population.

To successfully spawn, bigmouth buffalo prefer shallow, flooded terrestrial vegetation, but the addition of dams and channels along with the pumping of water for municipal and agricultural use are changing the ecosystem.

These activities have led to reduced water levels, and they have created physical barriers that have destroyed the bigmouth buffalo fish spawning habitat and limited their access to spawning areas.

Bryshun and his research team began their study by finding and capturing bigmouth buffalo fish for tagging. They loaded their boats with gear that included nets as well as all the surgical equipment needed to implant the tracking devices. Once on the water, they launched a long, sheet-like gill net into the lake. The net was made of thin mesh, so that the fish unknowingly swam into it and became caught.

Once removed from the net, the captured fish were taken to shore where the field crew had set up a folding table that became the surgery area. After being anesthetized, each fish was weighed, measured, and a few scales were removed for age analysis. Then the surgery began.

While water was continually pumped over the gills to ensure the fish could breathe, an abdominal incision was made, and a cylindrical transmitter was inserted. After suturing, each fish was monitored while coming out of anesthesia and then released back into the water.

Receivers placed at various locations within Buffalo Pound Lake as well as throughout the Qu’Appelle River system were able to record signals from these implanted transmitters. Once the data was downloaded, it was used to determine the movement patterns of the bigmouth buffalo as well as its potential rival, the common carp.

Using the information gathered from this research project, the scientists aim to identify and mitigate potential threats to the bigmouth buffalo fish population. However, since the research project is still ongoing, the province has implemented several short-term strategies to help ensure that bigmouth buffalo distribution, population levels and habitat are maintained.

The province is modifying and replacing any water control structures in the Qu’Appelle River system that hinder movement of the fish, and they are eliminating berms which can raise the water level in wetlands and interfere with the spawning habitat of the bigmouth buffalo.

The province is also putting signage at fishing locations to educate the public and avoid misidentification. As well, provincial representatives are advising cabin owners about the impact of actions such as applying lawn chemicals — a practice that greatly affects water quality and habitat in the surrounding area.

“First, the public needs to know [bigmouth buffalo fish] exist,” says Ferrari. “Second, [they need] to understand the impact we have on them. In areas where there are lots of cabins, the bigmouth buffalo spawning habitat is reduced. People need to learn how they can modify their activities to avoid impacting water quality.”

Through the combination of research at USask, protection under SARA, conservation activities and co-operation from the public, the USask researchers are hopeful they can reverse the trend and increase the population of the bigmouth buffalo in Saskatchewan.

Gabrielle Achtymichuk of Outlook, Sask., will begin her third year of veterinary studies at the WCVM in August 2019. Her story is part of a series of articles written by WCVM summer research students.