Spatial Distribution-Abundance Relationships in Juvenile (Age-0) Red Drum (Sciaenops Ocellatus) and Spotted Seatrout (Cynoscion Nebulosus). II: Influence of Major Disturbances

Abstract

Local species populations that are more numerically abundant and occupy a greater proportion of the landscape relative to other species often recover more quickly (i.e., are more resilient) following local-scale environmental perturbations. In a companion study, we found that seatrout juvenile populations were distributed more broadly across Tampa Bay, Florida, and numerical abundance was generally much higher than those of similar-sized red drum, suggesting that spotted seatrout may also be generally more resilient to population declines than red drum. Following major population declines over a 12-year period (1996–2008), we found that larger juveniles of seatrout (51–100 mm standard length) simultaneously gained numerical abundance and broadened their spatial distribution generally within the next year. Population recovery in the same size of juvenile red drum generally took multiple years, and distribution and abundance increases were not always concurrent during the recovery period. Despite their overall higher abundance and broader spatial distribution, the smaller-sized juveniles of spotted seatrout (15–50 mm standard length (SL)) did not always recover more quickly from population declines compared with similar-sized red drum. Populations of the smaller-sized juveniles of both species often took multiple years to recover and showed non-concurrent increases in distribution and abundance during recovery. Despite their relatively narrow spatial distribution, juveniles of red drum may increase their overall resilience to local environmental perturbations by occupying multiple isolated patches across the Tampa Bay landscape. Monitoring dynamics of numerical abundance and spatial distribution may be helpful in gauging relative population resilience to facilitate overall management of these fishery populations.