Geology topics

Eli G. Lampo

Publications and source records attributed to Eli G. Lampo.

2 recordsLinked to original sources

USGS2023

Predation of invasive silver carp by native largemouth bass is size-selective in the Illinois River

Silver carp ( Hypophthalmichthys molitrix ) are a nonnative, planktivorous, and highly invasive species of cyprinid located throughout the Mississippi River Basin. Although they co-occur with largemouth bass ( Micropterus nigricans ), an abundant native predatory fish, their predator–prey relationship is poorly understood. This potential relationship warrants investigation as largemouth bass are large-gaped predators capable of exhibiting top-down control on planktivorous fishes. The objectives of this study were to determine if largemouth bass consume juvenile silver carp, and if there was a relationship between length of largemouth bass and length of silver carp consumed. Largemouth bass were collected from the La Grange Pool of the Illinois River using 60 Hz-pulsed DC electrofishing and their diets were analyzed (n = 389, total length = 70–578 mm). Evidence of silver carp was present in 18% of diets of largemouth bass that consumed fish. Lengths of consumed silver carp were estimated from the dimensions of their recovered chewing pads or pharyngeal teeth in the stomachs of largemouth bass. A significant relationship between length of largemouth bass and length of silver carp consumed ( p < 0.001, F = 34.63, r 2 = 0.61) was observed. Estimated total lengths of silver carp were 34–101 mm and were recovered from diets of largemouth bass that were 94–262 mm total length. These results indicate enhancement of native largemouth bass populations is unlikely to substantially reduce silver carp populations in the Illinois River or in other waterways where these species co-occur.

Illinois↗

USGS2017

Using pharyngeal teeth and chewing pads to estimate juvenile Silver Carp total length in the La Grange Reach, Illinois River

The Silver Carp Hypophthalmichthys molitrix is an invasive species in the Mississippi River basin; an understanding of their vulnerability to predation as juveniles may inform control by native predators and predator enhancement (e.g., stocking). Digestion of Silver Carp prey recovered from diets makes it difficult to determine the size‐classes that are most vulnerable to predation by native fishes. The objective of this study was to determine whether the sizes of the chewing pad (CP), pharyngeal teeth (PT), and pharyngeal arch (PA)—the Silver Carp structures most often found intact in predator diets—were predictive of the TL of prey Silver Carp. During 2014 and 2015, juvenile Silver Carp ( n = 136; <180 mm) were collected using 60‐Hz pulsed‐DC electrofishing and mini‐fyke nets in the La Grange reach of the Illinois River. We extracted Silver Carp CPs ( n = 136 fish) and PAs with PT intact ( n = 129 fish) and measured CP length (CP L ) and width (CP W ), eight reproducible PT landmarks (PT1 L –PT4 L ; PT1 W –PT4 W ), and four reproducible PA landmarks (PA1–PA4) to the nearest 0.01 µm. Using simple linear regression, we found a strong predictive relationship between measurements of CP, PT, or PA and the TL of Silver Carp. The CP L ( r 2 = 0.94) and CP W ( r 2 = 0.94) had the strongest relationships with Silver Carp TL, followed by PA1 ( r 2 = 0.89) and PT1 L ( r 2 = 0.87). These strong relationships suggest that all three structures could be used in diet analyses to accurately estimate Silver Carp TL and thus further our understanding of predator–prey dynamics for this high‐risk invasive species.

Illinois↗