2025 Midwest Fish & Wildlife Conference

AUTHORS: Kaiden Vinavich, Illinois Natural History Survey; Levi Solomon, Illinois Natural History Survey; Sam Schaik, Illinois Natural History Survey; Jesse Williams, Illinois Natural History Survey; James Lamer, Illinois Natural History Survey; Edward Sterling, US Fish & Wildlife Service, Columbia, MO; Ben Marcek, US Fish & Wildlife Service, Carterville, IL; Michael Weber, Iowa State University; Christopher Sullivan, University of Connecticut; Mark Fritts, US Fish & Wildlife Service, La Crosse, WI; Allison Lenaerts, Illinois Department of Natural Resources; Emily Szott, Illinois Natural History Survey; Zack Witzel, Minnesota Department of Natural Resources; Brandon Harris, Illinois Natural History Survey

ABSTRACT: Invasive carp, composed of bighead (Hypopthalmichthys nobilis), silver (H. molitrix), grass (Ctenopharyngodon idella), and black carp (Mylopharyngodon piceus), have negatively impacted the food webs and native biota of the Mississippi River Basin since their introduction in the late 1970s. Harvest is the primary management strategy to reduce invasive carp populations, however, due to their complicated life history and absence of robust population estimates, additional assessment tools are needed to help evaluate the effectiveness of harvest. Therefore, we are exploring variation in invasive carp annual growth as a surrogate for invasive carp density in response to management and removal efforts. This will be accomplished through two main objectives: 1) build master chronologies and characterize invasive carp annual growth within discrete, spatially-explicit management units across a spectrum of invasion densities in the Mississippi River Basin and 2) model growth response to management (harvest) and ecological/environmental drivers (e.g., zooplankton abundance, cumulative growing degree days, year-class strength, and hydrology). We will evaluate growth through incremental lapillus otolith measurements from bighead and silver carp across reaches of the Upper and Lower Mississippi River, Illinois River, Missouri River, Ohio River, and select tributaries ranging from 2014-2024 (n=50; 25 male, 25 female per species, per reach, per year). A mixed effects modeling approach will be used to estimate annual growth in response to management and external drivers, while adjusting for allometric and individual-specific growth intraclass variation. The results of this work will yield master invasive carp chronologies across their invaded range, capturing several stages of their invasion throughout the Mississippi River Basin and hopefully serve as a baseline for future collections and a tool to help evaluate management success.