The butterfly mussel as seen in Cumming and Mayer, Field Guide to Freshwater Mussels of the Midwest.

Biologists from Illinois Department of Natural Resources (DNR), Illinois Chapter of The Nature Conservancy (TNC), and Genoa National Fish Hatchery (NFH) this August began a partnership to propagate butterfly mussels.  Illinois DNR classified the butterfly mussel as a species of greatest conservation concern in the State’s Conservation Action Plan.  A state wildlife grant was awarded to TNC to begin propagation efforts for the butterfly mussel.  Because of the existing relationships formed in the recovery efforts for the federally endangered Higgins eye pearlymussel, Illinois DNR and TNC approached Genoa NFH to provide technical assistance for their butterfly mussel program.  Genoa NFH provided blue prints for propagation cages and floating assemblies that TNC then manufactured for the program.  The Nature Conservancy organized a mussel collection party on the Mississippi River in which 18 volunteers from Illinois Natural History Survey, Western Illinois University, TNC and Illinois DNR collected 56 butterfly mussels.  Once the mussels were collected, Illinois DNR sent out shocking boats to collect freshwater drum that are needed to help the butterfly mussels complete their life cycle.  The larval form of the butterfly as well as most mussels must attach to the gills or fins of a host fish where they undergo a metamorphosis and then excyst off the fish to begin their independent juvenile life stage.  After the freshwater drum were collected, the mussel biologist from Genoa NFH joined TNC and Illinois DNR at the Merwin Preserve at Spunky Bottom, IL.  After examining the mussels and finding only one female with a few larva, the biologists determined that they had missed the mussel’s spawning season.  All was not lost however, it was then decided to conduct a density study to determine how many fish to place per culture cage.  Freshwater drum are easily over stressed by handling and confinement resulting in high mortality.  Results from the density study will help maximize effort by reducing mortality due to crowding in the cages.  A second effort to propagate butterfly mussels will be attempted in May 2009.