DON DENNERLINE AND MICHAEL J. VAN DEN AVYLE, Georgia Cooperative Fish and Wildlife Research Unit, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602-2152, USA

As part of a larger long-term monitoring project, blueback herring Alosa aestivalis have been sampled with experimental horizontal and vertical gillnets periodically since 1989. These targeted efforts were prompted by debate among resource managers regarding the longitudinal distribution of blueback herring within the reservoir across seasons. Specifically, some managers believed the distribution of blueback herring was restricted during stratified periods by the "temperature and dissolved oxygen squeeze" noted for striped bass and other species in southern impoundments. Therefore, the objectives of targeted blueback herring sampling were to characterize temperature selection by blueback herring, to determine the spatial distribution of blueback herring seasonally, and to relate the distribution of blueback herring to the availability of specific ranges of temperature and dissolved oxygen. Preliminary analysis shows that most herring are sampled at temperatures of 150 - 200 C during the summer regardless of depth and at dissolved oxygen levels of less than 2 ppm. Longitudinal distribution of blueback herring varies across years (i.e., fish are more widespread in some years) and can be related to differences in water quality across years. The influence of upstream reservoir operations on the longitudinal distribution of "available habitat" and implications regarding the suitability of blueback herring as forage for coolwater species in southern impoundments will also be discussed.