Estuarine habitat ecology of adult weakfish (Cynoscion regalis): A multi-scale approach.

摘要

The habitat ecology of adult weakfish (Cynoscion regalis) remains poorly understood, although they comprise an important ecological and economic portion of estuarine environments. Weakfish are particularly susceptible to confusion over how to best delineate important habitat resources, such as those used for reproduction, because they may change over multiple spatial (coastal and estuary) and temporal (seasonal and diel) scales. In this study, weakfish habitat dynamics were evaluated at multiple scales using acoustic telemetry within the Mullica River-Great Bay estuary in southern New Jersey. At the broader estuary scale, residency, habitat use, and movements were quantified across the reproductive/post-reproductive season. Tagged adult weakfish were resident in bay, lower river, and subtidal creek habitats during reproduction (May through July) and following the reproductive season (August through November) but showed limited use of inlet and upriver habitats in both seasons. Movement rates increased at the end of the post-reproductive season and weakfish apparently moved into fringing, unmonitored habitats within the study area following the reproductive period. Estuarine egress occurred throughout the study period but was lowest during July and highest during the final month of emigration in November. At smaller spatial scales, weakfish displayed patterns of site fidelity both seasonally and daily. At the seasonal scale, a majority of weakfish tagged in 2008 maintained fidelity to their original tagging location or established new "core areas" in other parts of the estuary. In both cases, fish were detected at these areas for the duration of their residency or made short- or long-term excursions before returning to their original core area. At the diel scale, weakfish displayed movements of varying distances from their original tagging location beginning around sundown and returning around the sunrise period, which also corresponds to the timing of nightly weakfish reproduction. These findings represent new evidence of the role that estuary habitats may play in adult weakfish life history and, because weakfish habitat dynamics may be influenced by reproduction, it will be important to incorporate these changes into future management of the fishery.