Smith, J. A., and J. E. Hightower. 2012. Effect of low-head lock and dam structures on migration and spawning of American shad and striped bass in the Cape Fear River, North Carolina. Transactions of the American Fisheries Society 141:402-413.
Abstract
Anadromous fish populations within the Cape Fear River, North Carolina have declined substantially since the late 1800s. Three low-head lock and dam structures contributed to this decline by limiting access to upstream spawning habitat. We used egg sampling and sonic telemetry to examine the effects of the lock and dam structures on migration and spawning activity of American shad Alosa sapidissima and striped bass Morone saxatilis. Egg distribution and stage of development suggest that most American shad spawning took place downstream of the lowermost lock and dam (LD-1). The predicted mean density of stage-1 American shad eggs at a water temperature of 21 °C was 895 per 1,000 m3 (95% credible interval 800-994) below LD-1, 147 (103-197) below the second lock and dam (LD-2) and 32 (17-49) below the uppermost lock and dam (LD-3). The probability of capturing a stage-1 American shad egg was strongly dependent on water temperature and hour of egg collection. Transmitter detections for 20 sonic-tagged American shad and 20 striped bass in 2008 showed that the majority of both species moved upstream of Lock and Dam 1, with 35% of American shad and 25% of striped bass migrating upstream of LD-3. Based on passage rates at the three locks and dams, American shad would be expected to be most abundant downstream of LD-1 and upstream of LD-3. For striped bass, the section of the river between LD-2 and LD-3 had the highest egg collections and highest predicted proportion of the run. In combination, these results demonstrate that the locking program provides some access to historical spawning habitat, although further improvements in fish passage could benefit both species.