John U. Crutchfield, Jr.

Ecological Changes Following an Alewife Introduction in an Oligotrophic Reservoir: A Case History

Fisheries Outstanding Technical Paper

Alewife (Alosa pseudoharengus) was introduced into oligotrophic Mayo Reservoir, North Carolina, during 1992 or 1993. The species established a self-sustaining population and increased from <1% of total fish biomass in 1993 to 31% in 2000. Size-selective planktivory by the species, a well-documented phenomenon in other alewife introductions, was implicated in observed changes in the reservoir zooplankton community. Large- and mid-sized zooplankton (> 0.7 mm) (Onchyodiaptomus birgei, calanoid copepodites, Daphnia spp., Diaphanosoma brachyurum, and Holopedium gibberum) decreased in...


Comparison of Population Estimates on a Known Largemouth Bass Population

Population estimates were calculated for a known young-of-the-year (Y-O-Y) largemouth bass (Micropterus salmoides) population in a Piedmont North Carolina pond. Bass were collected by electrofishing for 6 consecutive nights. Estimates were derived using capture-recapture (Chapman, Chapman modified Peterson, Schnabel, and Schumacher-Eschmeyer) and removal (Leslie and DeLury) methods. Accuracy and bias of population estimates for each method were assessed from a statistical framework. All methods gave negatively biased estimates. Schumacher-Eschmeyer and DeLury exponential catchability...