Detection of Lake Erie Cisco using eDNA – Applications to Cisco Restoration in the Laurentian Great Lakes

Joseph D. Schmitt (USGS, jschmitt@usgs.gov), James Roberts (USGS), Richard Kraus (USGS), Mark DuFour (USGS), Corbin Hilling (USGS), Meredith Bartron (USFWFS)

Lake Erie cisco Coregonus artedi once supported the largest freshwater fishery on earth (Van Oosten 1934); however, the fishery collapsed in the 1920s and the species was functionally extinct by the 1960s (Regier et al. 1969). While a few “cisco-like” fish have been captured in Lake Erie during subsequent years, the majority have been bloaters and bloater hybrids (CWTG 2017). In 2019, scientists from the Lake Erie Biological Station expanded their sampling efforts into December and captured one ripe male cisco from Niagara Reef in the West Basin of Lake Erie (Figure 1). Surveys were cancelled in 2020 due to the pandemic; however, two more ripe cisco (one male and one female) were captured and another was lost at the boat on Niagara Reef during the two sampling events that occurred in December of 2021. Three cisco have now been captured after extending sampling efforts into the month of December. These fish were captured with minimal sampling effort; a total of three overnight net deployments. Morphometric analysis (J. Schmitt) and genetic analysis (A. Ackiss) indicate that these fish are C. artedi and are most similar to contemporary cisco from the main basin of Lake Huron. It is unclear if these cisco hatched in Lake Huron, or if they have been present in Lake Erie for some time and hatched on Niagara Reef. They were not OTC marked and, while they are morphologically very similar to main basin Lake Huron morphotypes (Eshenroder et al. 2021), they exhibited differing fin lengths and gillraker counts, though sample size is quite small. All fish expressed eggs and milt when handled, suggesting they are prepared to spawn at Niagara Reef – a habitat consistently utilized by lithophilic spawners. The proposed study will determine whether cisco can be detected via paired net and eDNA sampling on Niagara and other nearby reefs in Lake Erie. Sampling for cisco via molecular techniques would be a useful addition to gill net sampling due to the volatility of Lake Erie in December. Collecting water samples represents a much safer and consistently achievable alternative to only setting/retrieving gillnets, as the samples can be gathered during short variable weather windows. If we can detect cisco via eDNA at the proposed sites, we could expand sampling into historical spawning locations across the lake that exhibit similar habitat characteristics. Understanding when and where contemporary Lake Erie cisco are spawning, even if they are of Lake Huron origin, would be incredibly valuable should future reintroductions occur. Lake Erie is an especially valuable case study as cisco densities are so low – the three cisco captured by USGS represent some of the only C. artedi that have been seen in Lake Erie during the past few decades (CWTG 2017). The successful application of eDNA sampling here would support transferring the approach to the other Great Lakes.