For the love of suckers: Volunteers contribute to research on key freshwater fishes

A new paper published today, led by Chicago’s Shedd Aquarium, reveals how volunteers across Illinois, Wisconsin and Michigan enabled researchers to gather seven years of data on the spawning migrations of suckers, an understudied yet essential group of freshwater fishes. Using observations collected by trained members of the public, the collaborative team of researchers have discovered that temperature is the primary trigger for sucker spawning migration, which can help inform conservation strategies in light of a changing climate.

“We believe that conservation of native, non-game fishes will only be effective if concerned members of the public are advocating for the animals as well as their environments,” said Dr. Karen Murchie, director of freshwater research at Shedd Aquarium and lead author on the study. “Our volunteer network highlights the untapped potential for involving the public in studies on migratory fishes.”

To address the lack of knowledge about suckers and boost public appreciation of these non-game fishes, the research team developed the idea of a program enlisting help from volunteers to monitor the timing of sucker migration. This included monitoring creeks and rivers for the presence of white suckers (Catostomus commersonii) and longnose suckers (Catostomus catostomus) along the western shore of Lake Michigan and southern shore of Lake Superior.

Volunteers across three states went to a specific monitoring site every day for six to eight weeks during the spring. At the site, volunteers recorded various environmental conditions and documented the absence or presence of suckers. Additionally, a data logger in the water regularly recorded the temperature and water depth, which was used to assess migration cues.

From 2017 to 2023, 77 unique volunteers participated in the program with an average of 45 volunteers per year. During most years, the network of volunteers monitored at least 14 tributaries each day – a much wider range than any single institution could accomplish. Through the program, volunteers became strong advocates for suckers. They shared conservation messaging with their peers, garnering invaluable support for restoration efforts and shifting the public perception of native non-game fishes.

“Prior to my involvement in this program, I always thought of suckers as a ‘rough fish,’” said Frank Langley, a volunteer. “My viewpoint has now dramatically changed, and I enjoy sharing the importance of suckers to the ecosystem with others while at the field site and elsewhere.”

The data from the first seven years of monitoring reveal that temperature is the primary trigger for sucker spawning migration. Specifically, migration usually begins when multiple days in a row reach a temperature of 6.3 degrees Celsius (43.3 degrees Fahrenheit) or higher. This finding has implications for local Great Lakes ecosystems, as warmer winters could result in suckers migrating early. This in turn can affect the nutrients and food available to other animals, many of which rely on suckers to survive.

Suckers are the most abundant migratory fishes in the Great Lakes region. They serve as a food source for many other animals (including gamefish, mammals and birds) and add important nutrients to the water when they reproduce. Despite these key benefits to freshwater ecosystems, suckers are understudied and underappreciated, with some people killing suckers and leaving them onshore under the misconception that they have no value.

“If you love trout, you can thank a sucker for helping them survive,” said Murchie. "Our volunteers play a critical part in raising awareness and compassion for suckers, and we encourage everyone to join in the effort to care for and conserve wildlife and freshwater ecosystems for generations to come.”

At Shedd Aquarium, guests can connect with local freshwater species – including suckers – in the At Home on the Great Lakes gallery. Shedd also offers other regular volunteer opportunities in local natural areas to restore and protect spaces for people and animals alike. Individuals or groups looking to make a difference can sign up for Action Days.

The full findings from this research have been published in a special edition of Environmental Biology of Fishes under the title, “For the love of suckers: scientific benefits of engaging volunteers to monitor migrations and advocate for native non-game fishes.”