Mysis ecology in the Great Lakes

Jim Watkins, Lars Rudstam, Tom Evans, Hannah Blair, Kayden Nasworthy, Sarah Lawhun, Alex Koeberle, Toby Holda, Taylor Herne (Cornell), Brian O’Malley(USGS), Dave Warner (USGS), Steve Pothoven (NOAA-GLERL), Kelly Bowen (DFO Canada), Warren Currie (DFO), Rosaura Chapina and Jason Stockwell (University of Vermont), Alexander Karatayev and Lyubov Burlakova (Buffalo State College). (Funded by US EPA GLNPO, USGS, and GLFC)

Mysids are an important native species in all the Great Lakes as well as other inland lakes. Understanding mysid ecology is an essential component of understanding these systems as the species is both a major predator on zooplankton and a major prey for alewife, smelt and native coregonids. Historic declines in mysids, changing prey-fish communities, and oligotrophication in the Great Lakes have caused scientists to question the long-term reliability of mysids as a food source and to further investigate population dynamics and drivers of change. 

We continue to combine monitoring data of EPA generated by CBFS with that of several other agency surveys now yielding an extensive time series from 1990 to 2025. Mysid abundance was added as a new sub-indicator in the State of the Great Lakes (SOGL) reporting cycle for 2025. Mysis abundance in lakes Ontario and Superior is currently highest of the Great Lakes and stable, while those of Lake Michigan have experienced a recent dramatic decline, and those of Lake Huron are low. 

Toby Holda completed his PhD in 2025. His dissertation chapters include two published works including 1) analysis of extensive net catches for mysid assessment and life history in Lake Michigan in 2015, 2) cross-lake analysis of mysid net catch time series for all five Great Lakes, and 3) definition of several acoustic material properties of mysids. Toby truly made an impact on mysid research in the Great Lakes.  

Sarah Lawhun completed her MS in 2025. With the help of our Buffalo State collaborators, Lawhun tested the use of day and night collected ponar dredge data to assess mysid use of benthic habitat in general and specifically the extent of partial diel migration with some component of the population not migrating off the benthos. She was recently hired by the NYS Department of Health and is preparing her manuscript for submission. 

Kayden Nasworthy is continuing his MS/PhD program. His MS thesis chapter was recently accepted by the Canadian Journal of Fisheries and Aquatic Sciences, where he used lakewide hydroacoustic data collected by the autonomous Saildrone in 2021 for lakes Michigan and Huron. He developed a hypothesis that mysids in several of the Great Lakes are now limited by the extent of dark daytime habitat in each lake that is shrinking due to increases in water clarity. This change in light regime increases fish predation pressure on mysids. We wrapped up one GLFC project in 2025 and were funded for a second two-year project that Kayden will be involved in- using a two decade fishery acoustic time series in Lake Michigan to track mysid distribution as a further test of his dark refuge hypothesis.