Suitability of Lake Erie for spawning and maturation of silver and grass carp

Silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idella) were introduced to US waters in the 1970s as biological control agents and potential foodfish.  They soon escaped captivity, and self sustaining populations now exist throughout the lower Mississippi, Missouri, and Ohio Rivers.  Their range has extended to the Des Plaines River, where they now threaten to enter Lake Michigan via the Chicago Sanitary and Ship Canal, which connects the Des Plaines River to Lake Michigan.  We examined literature from the native range of these carps for minimum total annual degrees days for maturation and spawning and compared that to present thermal conditions in Lake Erie using water temperature data.  We also estimated date spawning begins based on annual degree days.  Thermal conditions are suitable for spawning and juvenile development of these fish throughout Lake Erie and there are several potentially suitable spawning tributaries to western and central Lake Erie.  In Western Lake Erie, first spawn would likely occur in early June, which is considered the primary month for Asian carp spawning throughout their native and introduced range.  Thermal data support the conclusion that Lake Erie is suitable for maturation and spawning of silver and grass carp.