Mussels regaining a foothold in the upper Mississippi River after decades of decline

On a warm September afternoon, a boat glides quietly along the Mississippi River, its crew engaged in lighthearted banter. As they navigate the waters between St. Paul and Minneapolis, the scene appears to be a casual fishing trip. However, the contents of their cooler tell a different story: nestled within are approximately 400 mucket and Higgins eye mussels, each a little over an inch in diameter, ready to be reintroduced into their native habitat. This operation, led by dedicated biologists from the Minnesota Department of Natural Resources (DNR), represents a significant step in the ongoing effort to restore the population of these vital aquatic organisms.

What Happened

Since 2001, the DNR has been diligently working to reintroduce native freshwater mussels into the upper Mississippi River, a stretch that had been devoid of these creatures for decades. In total, they have released around 45,000 mussels, including the mucket, Higgins eye, snuffbox, and winged mapleleaf species, all of which are classified as threatened or endangered under state or federal legislation. This year marks a pivotal moment in their restoration efforts, as the biologists have observed promising signs of recovery in the local mussel populations.

“You spend five years raising these little guys just to throw them out,” remarked Lindsay Ohlman, a propagation biologist at the DNR, reflecting on the bittersweet nature of the task. The mussels, now five years old, have a long life ahead of them, potentially living for up to 50 years. Their introduction into the river is not just a matter of replenishing a species; it is about restoring the ecological balance that has been disrupted for over a century.

The decline of freshwater mussels in the upper Mississippi began in the late 1800s, largely due to the burgeoning pearl button-making industry. Founded by German immigrant John Boepple in Muscatine, Iowa, this industry thrived on the abundant supply of mussel shells, leading to the overharvesting of these creatures. At its peak, Muscatine produced 1.5 billion buttons annually, accounting for more than one-third of the world’s button production. As demand surged, the once-plentiful mussel populations dwindled.

Historical Context

Freshwater mussels were once so abundant in Minnesota that the bottoms of lakes and rivers resembled cobblestone streets, according to historical accounts. However, as Ben Minerich, a freshwater mussel conservation specialist at the University of Minnesota, explained, the perception of mussels as an endless resource contributed to their decline. “They used to be so abundant, which is why they were being taken out [of the river] at such large amounts,” he said. Today, freshwater mussels are recognized as the most imperiled group of animals in North America, with over half of Minnesota's 51 native species listed as endangered or threatened.

Modern threats to mussel populations include the invasive zebra mussel, which competes for food and habitat, and the construction of locks and dams that fragment their natural habitats. The upper Mississippi River is now home to 29 locks and dams, which obstruct the migratory paths of both fish and mussels. This fragmentation has made it increasingly difficult for mussels to reproduce and thrive, as their larvae rely on fish to survive their early stages of life.

The Role of Freshwater Mussels

Freshwater mussels play a crucial role in maintaining healthy river ecosystems. They act as natural filters, removing bacteria, algae, and metals from the water, and their presence can help prevent erosion during flood events. When mussels congregate on riverbeds, they form mussel beds that provide habitat for a variety of aquatic creatures. “They’re a pretty complex animal, even though they don’t have a face,” Ohlman noted, emphasizing the ecological importance of these shellfish.

Despite the challenges they face, the DNR's reintroduction efforts have begun to yield positive results. Over the past 25 years, the agency has monitored the growth and survival of reintroduced mussels in various river systems, including the Cedar and Cannon River watersheds, where survival rates have been found to be between 40% and 80%. Although the exact survival rates for the Mississippi River have not yet been determined, there is optimism that similar outcomes will be observed.

As the DNR biologists prepare to release the mussels, they take care to tag each one, allowing them to track their growth and monitor their health over time. This meticulous approach underscores the commitment to ensuring that these mussels not only survive but thrive in their reintroduced habitats.

Community Impact

The resurgence of mussel populations in the upper Mississippi River is not just an environmental victory; it also has significant implications for the surrounding communities. Freshwater mussels contribute to water quality, which is essential for the health of local ecosystems and the well-being of residents who rely on the river for drinking water and recreation. The restoration of mussel populations can enhance biodiversity, support fish populations, and promote healthier aquatic environments.

Moreover, the efforts to restore mussels resonate with the values of commitment and stewardship that many community members hold dear. As families and individuals engage with the river—whether through fishing, boating, or simply enjoying the natural beauty—they are reminded of the importance of preserving their environment for future generations. The DNR’s work aligns with a broader vision of fostering a sense of responsibility for the land and water that sustains their lives.

What's Next

Looking ahead, the DNR plans to continue monitoring the mussel populations in the Mississippi River and adapt their strategies as needed. The successful reintroduction of mussels is a testament to the resilience of nature and the dedication of those who work tirelessly to protect it. As Ohlman and her colleagues prepare to conclude this phase of their efforts, they remain hopeful that the mussels will continue to flourish in their new home.

The journey of these mussels serves as a reminder of the interconnectedness of all living things and the importance of nurturing our natural resources. As communities rally around conservation initiatives, there is an opportunity for families to come together in support of a shared goal: a cleaner, healthier river that can sustain both wildlife and human life.

In the coming years, the DNR will expand its outreach efforts to educate the public about the significance of freshwater mussels and the role they play in the ecosystem. By fostering a deeper understanding and appreciation for these often-overlooked creatures, the DNR hopes to inspire a new generation of stewards who will advocate for the protection of their local waterways.