Expanded Electrofishing & Hoop Netting for Invasive Carp

Expansion of Standardized Electrofishing in the Peoria Reach

Long-Term Survey and Assessment of Large River Fishes (LTEF) completes annual sampling using boat-mounted pulsed-DC electrofishing in the Peoria Reach (amongst other sampling locations) of the Illinois River Waterway; however, LTEF sampling is limited to the main-channel border and some side-channel habitats. Sampling stratified-random off channel and backwater habitats will fulfill the knowledge gap of fish communities and provide a more complete assessment of the Peoria Reach. Sampling will begin in 2019 to cover the wide range of habitat types using Long-Term Resource Monitoring (LTRM) protocols to evaluate shallow water fishes. Sampling is conducted from June 15 to October 31 and fish data collected consists of species identification, length, and weight. Water quality data measured at each site consists of depth, dissolved oxygen, specific conductivity, velocity, Secchi transparency, and chlorophyll a.

The extension of electrofishing is to assess the native planktivores and fish communities in relation to the enhanced contracted commercial fishing efforts on bigheaded carp implemented by the Illinois Department of Natural Resources (IDNR) in the Peoria Reach. Planktivorous species (including bigheaded carp) are measured using metrics such as catch per unit effort (CPUE), community structure, relative weight, and proportional size distribution (PSD). Additionally, population demographic (age, growth, mortality) data is collected using post cleithra and lapillus otoliths from bigheaded carp.

Technicians dip-netting fish while boat electrofishing in a backwater area of the Illinois River.

Enhanced Detection of Black Carp in the lower Illinois River

Exotic black carp Mylopharyngodon piceus, a large bodied fish that feeds on mussels, have invaded the Illinois River system and have been recently captured in the Alton, La Grange, and Peoria Reaches of the lower Illinois River. With only a few captured individuals, little is known regarding population levels in invaded reaches. Since more robust population estimates are essential to management and control of this potentially harmful invader, we will be assessing the population of black carp in the lower Illinois River and efficacy of different baits used to collect them. Hoop nets baited with clam-based and cottonseed-based baits have collected black carp in the past, but have never been experimentally tested against a control to assess their efficacy. This direct comparison between baits, along with LTRM standardized hoop netting that uses soybean-based bait, will help us gain knowledge regarding black carp population levels, range expansion, life-history information, and insight regarding bait efficacy. Additionally, all by-catch will be identified, measured, weighed, and enumerated for a complete assessment of bait efficacy.

Staff pulling a hoop net
Technicians pulling a hoop net from the Illinois River.

Funding, for both projects, is provided by the Illinois Department of Natural Resources through the Great Lakes Restoration Initiative.

These projects are coordinated by Sam Schaick and Jesse Williams at IRBS.