Abiotic and biotic factors influence the habitat use of an estuarine fish

For migratory fishes that occupy multiple habitats, surveys conducted at different scales may be required to assess habitat use. We used generalized additive models (GAMs) to relate water quality, microhabitat, geographic, and temporal factors to catches of 2 age classes of subadult red drum Sciaenops ocellatus from a 6 yr fishery-independent gill net survey in North Carolina, USA. Age-1 and age-2 red drum were most often caught in shallow, nearshore waters; in some regions, both showed a preference for seagrass. Age-1 red drum were primarily captured at 2 different salinity ranges (0 to 5 and 20 to 30 psu), while age-2 red drum abundance was not related to salinity. A smaller-scale analysis of 36 telemetered age-2 red drum in a small tributary of the Neuse River showed a negative response to salinity, a positive response to dissolved oxygen, a dome-shaped response to prey evenness, and a positive response to total prey. Although subadult red drum can tolerate a wide variety of environmental conditions, our research suggests that they associate with both abiotic and biotic factors in very specific ways. Habitat use patterns of subadult red drum were age-, scale-, and sometimes region-dependent, highlighting the need for examining habitat use patterns of estuarine organisms at multiple life history stages and scales if generalities about how species respond to abiotic and biotic factors are sought.