Timing and environmental factors associated with grass carp spawning in a Lake Erie tributary

Session: Invasive Species (3)

Nicole King, University of Toledo, Lake Erie Center, [email protected]
Madeline Tomczak, University of Toledo, [email protected]
Patrick Kocovsky, U.S. Geological Survey, [email protected]
Christine Mayer, University of Toledo, Lake Erie Center, [email protected]
Song Qian, University of Toledo, [email protected]

Abstract

Although grass carp have been captured in the Great Lakes since 1975, it was assumed that most were sterile or incapable of spawning in Great Lakes’ tributaries. However, spawning was documented in 2015 with the collection of eight eggs from the Sandusky River, Ohio, a Lake Erie tributary. Monitoring continued in following years and spawning was again documented in 2017. In 2017 the Sandusky River yielded 7,000+ eggs during two high flow events. Egg developmental stages were more variable at downstream sites and during lower flows; slower moving eggs are more likely to hatch in the river and survive to larvae. The pattern of egg stages and spatial distribution indicated spawning likely occurred several times or over a prolonged period. Although the hydrograph indicates that grass carp spawn during high flow events, it is unknown what proximal cues initiate spawning and what conditions increase the likelihood of egg survival. We back calculated spawning time based on egg stage and temperature to determine what factors may trigger spawning. Preliminary analysis indicates several spawning bouts over a >10 hour time period.  The ability to predict the timing and location of GC spawning and recruitment potential has implications for future control efforts.