The first endangered winged mapleleaf cultured in the recovery program. - FWS photo

 Mussel propagation has become a year round process at Genoa National Fish Hatchery (NFH) with the addition of the endangered winged mapleleaf to the growing number of species of freshwater mussels cultured at the facility. 

Freshwater mussels have a unique life cycle where the larval form of the mussel (glochidia) must attach to the gills or fins of fish in order to undergo a metamorphosis before leaving the fish to begin an independent life. 

Most of the mussels Genoa NFH works with typically release their glochidia in the spring of the year which means the these programs get underway in April, and production cages are monitored by October of the same year. 

The winged mapleleaf is quite different in that they release their glochidia in September/October of year 1.  The glochidia stay on the fish all winter long, and the fish are placed in production cages in May of year 2.  Due to the slow growth of the winged mapleleaf juveniles, production cages are not check until October of year 3. 

In September of 2006 Genoa NFH received 5 gravid winged mapleleaf mussels collected by divers from Minnesota Department of Natural Resources (DNR), Macalester College, the US Fish and Wildlife Service, and the St. Croix National Park Service.  Glochidia collected from these winged mapleleaf were then used to inoculate 620 channel catfish.

This is the largest inoculation of catfish with winged mapleleaf in the three year history of the program.  These catfish will be held at Genoa NFH in water that is chilled to mimic water temperature that would be experienced in the wild.  As the spring sun begins to warm up the river, the water temperature in the tanks of catfish will also be increased to mimic natural water temperatures before the fish are placed in production cages in the river. 

Cages placed in the spring of 2007 will be monitored for production in the fall of 2008.  Being the third year of the program, the first production cages were checked this passed October, and a total of 25 individuals were recovered from three cages. 

This is a small yet promising start to the recovery of the winged mapleleaf in the Upper Mississippi River System.   These 25 individuals may represent the first recruitment to the St. Croix River population of winged mapleleaf in many years.