Effect of demography on spatial distribution: movement patterns of the Albemarle Sound-Roanoke River stock of Striped Bass (Morone saxatilis) in relation to their recovery

摘要

We analyzed tag returns from a long-term tagging program to evaluate the movement patterns of the Albemarle Sound-Roanoke River (AR) stock of Striped Bass (Morone saxatilis) during a period of stock recovery in 1991-2008. The AR stock was found to increase its movement outside the Albemarle Sound estuary (from <4% to 15-31%) as it recovered from 1991 to 2008. Analysis with multinomial logistic regression where recapture area was modeled as a function of fish size and stock abundance indicated that Striped Bass from the AR stock exhibit a strong size-dependent emigration pattern. Larger (older) adults >600 mm in total length (TL) were much more likely to emigrate to ocean habitats (after spawning) than were smaller adults (350-600 mm TL), which mostly remained in inshore estuarine habitats. Smaller adults showed evidence of density-dependent movement and were recaptured only in adjacent estuarine systems, the Pamlico Sound and lower Chesapeake Bay, during periods of increased stock abundance. Assessment and management strategies for the AR stock of Striped Bass could be improved by accounting for movement (and hence harvest) outside the currently assumed stock boundary. More broadly, this study illustrates that changes in the demographics, such as size structure and total abundance, within fish populations can result in major shifts in their distribution and that long-term tagging data are useful in detection of such population-level changes in movement patterns