Utilization of salt marsh edge habitats by newly settled Sciaenids in a subtropical estuary

Abstract

Postsettlement patterns of habitat use along salt marsh shorelines of West Galveston Bay, Texas were examined for the bay spawning spotted seatrout (Cynoscion nebulosus), inshore spawning red drum (Sciaenops ocellatus), and offshore spawning Atlantic croaker (Micropogonias undulatus) from the family Sciaenidae. Collections were made monthly May through December 1997 and semimonthly September through November 1998 using a 1.5-m beam trawl towed along the outside edge of salt marshes. In 1997, C. nebulosus were collected May-October peaking in June (0.438 m⁻² [] 0.245 SE). Sciaenops ocellatus occurred September-November peaking in September (0.085 m⁻² [] 0.059), while M. undulatus occurred October-December peaking in November (0.305 m⁻² [] 0.098). Over 98% of the fish collected were < 30 mm SL. Density of all three species was positively associated with water depth and percent cover of vegetation. In addition, positive associations occurred for C. nebulosus with temperature and salinity, and S. ocellatus with water depth in vegetation. Cynoscion nebulosus were smaller, and significantly more numerous, along interior bay sites than near the tidal pass. Conversely, S. ocellatus were collected in significantly higher numbers, and smaller sizes, at sites near a tidal pass than at interior bay sites. A similar, but nonsignificant, trend was observed for M. undulatus, which occurred in high numbers near the tidal pass as well as at remote tidal creeks. Few C. nebulosus and S. ocellatus were collected from remote tidal creeks, although the majority collected were larger than occurred at other sites. No size difference occurred among M. undulatus collected at tidal creek, pass area, and bay area sites. At varying distances from the tidal pass, variability in density was high for all three species. Interannual variability was lower for the bay spawning C. nebulosus than for the other two species. This research suggests that settlement of C. nebulosus and S. ocellatus is greater at sites near the larval supply; interior bay and tidal pass areas, respectively. Micropogonias undulatus patterns were more complex with settlement occurring at salt marsh habitats in various locations within a bay.