Higgins Eye subadults await relocation inside Genoa's clam palace. - FWS photo

Thousands of the Federally listed Higgins Eye Pearly Mussel were returned to the Mississippi River Basin this past week, in what was perhaps the largest reintroduction of an Endangered Species since the inception of the Federal Endangered Species Act. 

More than 8,600 two- and three-year-old mussels were placed in the Rock River and Pool 16 of the Upper Mississippi River mainstem after being raised in mussel rearing cages in Pool 4 of the Upper Mississippi River.  

The mussels will be sleeping in a new bed, so to speak, as it is hoped that they acclimate to their new surroundings and begin producing young on their own in the next one to three years.  These locations were selected as release sites after careful examination to ensure that zebra mussel colonization at the release sites were low enough to not cause complications with Recovery efforts.  

The Higgins Eye Pearlymussel was one of the first species protected by the Endangered Species Act, and was listed as Endangered in 1976.  With the introduction of the zebra mussel, its survival was even more precarious, as the colonization of zebra mussels directly on native mussel beds interfere with normal feeding, respiration and reproduction.  

This multi-agency propagation effort began in 1999, and has produced over 30,000 Higgins Eye mussels to ensure the species survival.  The mussels are being propagated in hopes of producing 5 naturally reproducing populations made of multiple year-classes. 

Although still in the early stages of success, the latest stockings hold out hope that Recovery for this species has at least past the tipping point and is now heading in a positive direction.  

Native mussels are an important part of the ecosystem, supplying food, bottom stabilization and even water purification by filtering water through their respiration and feeding processes. 

The Upper Mississippi River Basin still holds one of the most diverse mussel populations in the world, though over 50% have experienced declines rangewide or are listed as imperiled by various Federal and state fish and wildlife agencies and concerned conservation groups.