Novel experimental technique to confirm fish hosts for “large river mussels”

Abstract

Unionid mussels are declining in North America. The larval stage (glochidium) represents a life-history bottleneck because glochidia are parasitic and require an appropriate fish host. However, appropriate fish host species for many mussel species are still unknown, making it difficult to implement effective conservation measures. Large-river migratory fish are suspected to be important hosts for mussels, but are difficult to work with and few have been positively confirmed as hosts in laboratory trials. I applied standard fisheries techniques to successfully capture, haul, and hold two problematic, large-river fish species; Alosa chrysochloris (skipjack herring) and Alosa alabamae (Alabama shad). I describe a new technique (gill excision) which facilitated the use of problematic fish for host assays and allowed me to provide the first laboratory conformation of fish host identity for Reginaia ebenus and Elliptio crassidens, as well as confirming that glochidia can successfully metamorphose from dead fish gills.