Investigation of Freshwater Mussel Glochidia Presence on Asian Carp and Native Fishes of the Illinois River

Abstract

Densities of introduced Asian carp (Silver Carp and Bighead Carp) in the Illinois River Basin are among the highest in the world. Asian carp have been reported to serve as hosts for Sinanodontawoodiana in their native territories, but no research has been conducted on the potential for Silver or Bighead Carp to host North American freshwater mussels. Our objectives were 1) to examine the presence of glochidia on native and non-native fishes from the Illinois River Basin, 2) to determine an optimal concentration and duration of potassium hydroxide (KOH) exposure for increasing transparency of preserved fish gills to more effectively detect the presence of glochidia and parasites, and 3) identify parasite burdens. Fifteen fish species (12 native and 3 non-native) were collected from the Illinois River Basin during summer of 2014. Preserved fins and gills of native and non-native fishes were examined for glochidia and parasite infections. We determined that a 20 min 5% KOH bath was optimal for increasing gill transparency. We recovered 242 glochidia from 5 native fish species: Bluegill, Largemouth Bass, Smallmouth Bass, Freshwater Drum, and Sauger. Based upon morphometric data, we were able to identify the glochidial larval stage of 5 groups of freshwater mussels: Group A-Lilliput, Group B- Threeridge, Group C- Deertoe or Fawnsfoot, Group D- Threehorn Wartyback, and Group E-Fragile Papershell. We did not locate glochidia on any of the non-native fish species. Future research should include the use of laboratory host trials to elucidate if Asian carp could serve as successful host fishes for native mussels or if they are recruitment sinks, a possibility that could have a major impact on the future stocks of currently imperiled freshwater mussels.