Blue catfish (Ictalurus furcatus) gut passage as a vector for the dispersal of invasive bivalves

The introduction and spread of invasive species is of great concern to natural resource managers in the United States.  Managers must be aware of the multitude of dispersal methods used by these organisms. We investigated the potential for survival of zebra mussel (Driessena polymorpha) and Asian clam (Corbicula fluminea) through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for these invasive bivalves. Blue catfish are particularly likely to facilitate their spread because they forage on mussels and lack molariform pharyngeal teeth required to crush shells. Blue catfish sampled from Sooner Lake, Oklahoma, were transported to a wet laboratory and placed into individual tanks (n=7). After 48 hours, fish were removed and all fecal material was collected and inspected for live mussels.  We found that 0 - 65% of the 18 - 767 zebra mussels recovered per fish and 30 - 82% of the 9 – 130 Corbicula recovered per fish, were alive. These estimates are likely conservative because empty shells may have been consumed during their non-selective foraging.  As a result, we believe that survival through the gut of blue catfish is an effective dispersal method for these invasive bivalve species.