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Current status of non-native fish species in the St. Louis River estuary
Citation:
Peterson, Greg, H. Ramage, C. Hatzenbuhler, J. Barge, J. Hoffman, AND A. Trebitz. Current status of non-native fish species in the St. Louis River estuary. St. Louis River Estuary, Superior, WI, March 13 - 14, 2018.
Impact/Purpose:
Assessing temporal patterns in non-native aquatic species appearance and their subsequent distribution and abundance is an important aspect of invasion biology. Thanks to data sets compiled by EPA-ORD and other agencies, we have a robust multi-decade data set on fish composition in the St. Louis River Estuary a coastal system on Lake Superior that is a major shipping hub and an invasion hotspot. This poster, to be given at a place-based conference that attracts researchers, managers, and policy-makers, informs on the most recent non-native fish to arrive in this estuary, and updates the information time-line for various other non-native species. The fact that the three most recent arrivals are range-expanding North American species rather than Eurasian species suggests that while ballast water regulations may be preventing trans-oceanic species transport, cross-basin transport by domestic ships is still an issue. This work falls under SSWR research area 3.01A-2.1, and builds on invasive species early detection work conducted by EPA/ORD and other agencies and funded by the Great Lakes Restoration Act.
Description:
The fish community of the St. Louis River estuary is well characterized, thanks to fishery assessment and invasive species early detection monitoring by federal, state, and tribal agencies. This sampling includes long-standing adult/juvenile fish surveys, larval fish surveys begun in 2012, and an environmental DNA-based survey conducted in 2016. Until recently, 10 non-native fish species were known from the estuary (not counting deliberately introduced salmonids), with the most recent arrival, brook silverside (Labidesthes sicculus), first detected in 2010. The estuary now harbors two additional non-native species, white bass (Morone chrysops) and gizzard shad (Dorosoma cepedianum), which continues a trend of increasingly rapid non-native species arrival in recent years compared to the historic rate. Multiple white bass were found in 2016 and 2017 adult/juvenile fish surveys, with otolith annuli analysis indicating the presence of at least two year classes and suggesting 2010 as the earliest potential introduction year. White bass presence as larvae (vs. white perch) is being confirmed genetically. Only two juvenile gizzard shad have been captured to date (in 2017), but their DNA was found in multiple water samples from 2016. Brook silverside, white bass, and gizzard shad establishment in the estuary marks a substantial and disjunct range expansion for these North American species, with their dispersal likely facilitated by uptake and release of ballast water from inter-lake shipping. Our poster also reviews frequency trends for other non-native fishes in the estuary, of which the vegetation-associated tubenose goby (Proterorhinus semilunaris) now seems most abundant.