HABITAT USE AND MOVEMENTS OF SHORTNOSE AND ATLANTIC STURGEONS IN THE LOWER CAPE-FEAR RIVER, NORTH-CAROLINA

We conducted a gill-net survey and used sonic tracking to document the distribution and movements of adult shortnose sturgeons Acipenser brevirostrum and juvenile Atlantic sturgeons Acipenser oxyrhynchus in the lower Cape Fear River, North Carolina. Shortnose sturgeons were rare; only eight fish were captured from 1990 to 1993. The five fish we tracked occupied river kilometer 16-96 from early January to May. The presence of gravid females and the rapid (11.5-27.0 km/d), directed upstream migrations we observed provided evidence that shortnose sturgeons may attempt to reproduce in this drainage. We also documented the disruption of spawning migrations by dams and incidental gill-net capture, which may prevent these fish from ever reaching their spawning grounds. Atlantic sturgeon juveniles were relatively common and preferred deep areas (> 10 m) in the vicinity of the saltwater-freshwater interface (km 46). In summer they held position for extended periods and apparently fasted, but were more active (1.3 km/d) and ranged over a greater area during cooler water temperatures in fall, winter, and spring. Both species occupied regularly dredged areas and were present during dredging operations in the Wilmington Harbor.