Raabe, J. K., and J. E. Hightower. 2014. American shad migratory behavior, weight loss, survival, and abundance in a North Carolina river following dam removals. Transactions of the American Fisheries Society 143:673-688.
Abstract
Despite extensive management and research, American shad Alosa sapidissima populations have experienced prolonged population declines, and uncertainty about underlying mechanisms remains. In the springs of 2007 through 2010, we used a resistance board weir and passive integrated transponder (PIT) technology to capture, tag, and track American shad in the Little River, North Carolina, a tributary to the Neuse River with complete and partial low-head dam removals. Our objectives were to examine potential demographic differences in timing and habitat use and to estimate season weight loss, survival, and abundance. Males typically immigrated earlier than females, but otherwise exhibited relatively similar migratory patterns. Weight loss displayed a positive relationship with cumulative temperature during residence. Emigrating males lost 30% or less of their initial weight compared to 50% or less for females, indicating potential survival thresholds. Spawning season survival was low as estimates ranged from 0.07 to 0.17; no distinct factors (e.g., sex, size, migrations) contributing to survival were documented. Sampled and estimated American shad abundance increased from 2007 through 2009, but was lower in 2010. This new American shad spawning information may further aid restoration efforts.