Seasonal residency of adult weakfish (Cynoscion regalis) in a small temperate estuary based on acoustic telemetry: a local perspective of a coast wide phenomenon

Abstract

Weakfish (Cynoscion regalis, Bloch and Schneider), an economically important species, enter estuaries during migration along inner-continental shelf habitat for use as nursery, feeding, and spawning habitat. The residency and therefore seasonal turnover of individuals in estuarine habitat is unknown. Aspects of seasonal residency in the relatively unaltered Mullica River-Great Bay estuary in southern New Jersey were evaluated during 2007 and 2008. Acoustic telemetry revealed estuarine residency of adult weakfish (273–864 mm TL) on the scale of days to several months (mean: 55 days). Egress from the estuary occurred throughout the study period but was lowest during July and highest during the final month of detection in November corresponding to seasonally declining water temperatures. Individuals maintained a constrained distribution within the estuary relative to the available range of water quality parameters with average encountered temperature (22.8 °C), salinity (30.1), dissolved oxygen (6.9 mg/L), and pH (7.8) all being higher than the annual estuary-wide mean value. The long residence time indicated the importance of the estuary as a seasonal destination, rather than intermittent resting area for some individuals and points to a diversity of individual migration patterns typical of other species from this region. Given that weakfish used small estuarine habitats for extended periods in both years of this study, estuaries such as this one may serve as important sites for spawning, feeding and other functions.