Diploid Grass Carp in the Great Lakes: Tracking Origins through Otolith Chemistry

Session: 02b. - Status and Management of Invasive Carps in the Great Lakes

Jeffrey Miner, Bowling Green State Univ., Dept. Biological Sciences, [email protected]
John Farver, Bowling Green State University, [email protected]
Kevin Pangle, Central Michigan University , [email protected]
Greg Whitledge, Southern Illinois University, [email protected]
Duane Chapman, USGS, [email protected]
Patrick Kocovsky, U.S. Geological Survey, [email protected]
Seth Herbst, Michigan DNR-Fisheries, [email protected]

Abstract

Since 2012 when reproduction by Grass Carp in the Great Lakes was first detected, over 100 individuals from Lakes Michigan, Erie, and Ontario have been examined for ploidy, hatchery signature (O2 isotope otolith ?18O), and potential spawning origin (otolith microchemistry). Approximately 50% were obtained in Lake Erie, where efforts were undertaken to sample known (Sandusky and Maumee rivers) and potential spawning locations. Almost 80% of the Lake Erie-caught Grass Carp were diploid (fertile). Of these, we used oxygen isotope chemistry in otolith core regions and determined ~70% of these fish did not have a signature indicative of aquaculture ponds; these fish were either introduced to the Great Lakes as fertile individuals, gained access from wild sources or they were spawned in the Great Lakes. Ages of these fish ranged from yearlings to >25 years.  Core otoliths signatures (Sr:Ca ratios) were used to determine potential spawning locations.  At least three spawning regions appeared likely.  Signatures matching Sandusky and Maumee River water chemistry dominated, but a set of fish with markedly lower Sr:Ca ratios also occurred. Finally, it appeared that some fish made long distance migrations; fish collected in Lake Michigan and St. Lawrence River had otolith signatures representative of fish spawned in western Lake Erie.

1. Keyword
biological invasions

2. Keyword
invasive species

3. Keyword
fish populations

4. Additional Keyword
otolith chemistry

5. Additional Keyword
Asian carp