American Shad Migratory Behavior, Weight Loss, Survival, and Abundance in a North Carolina River following Dam Removals

Abstract

Despite extensive management and research, populations of American Shad Alosa sapidissima have experienced prolonged declines, and uncertainty about the underlying mechanisms causing these declines remains. In the springs of 2007 through 2010, we used a resistance board weir and 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 removals of lowhead dams. Our objectives were to examine migratory behaviors and estimate weight loss, survival, and abundance during each spawning season. Males typically immigrated earlier than females and also used upstream habitat at a higher percentage, but otherwise exhibited relatively similar migratory patterns. Proportional weight loss displayed a strong positive relationship with both cumulative water temperature during residence time and number of days spent upstream, and to a lesser extent, minimum distance the fish traveled in the river. Surviving emigrating males lost up to 30% of their initial weight and females lost up to 50% of their initial weight, indicating there are potential survival thresholds. Survival for the spawning season was low and estimates ranged from 0.07 to 0.17; no distinct factors (e.g., sex, size, migration distance) that could contribute to survival were detected. Sampled and estimated American Shad abundance increased from 2007 through 2009, but was lower in 2010. Our study provides substantial new information about American Shad spawning that may aid restoration efforts.

Comparison of 4 aging structures in the American shad (Alosa sapidissima)

“…It also composes an important forage base for many species of fishes (Ross, 1991). Populations of American shad have declined because of fishing pressure and dams that have caused a loss of access to their spawning grounds (Ross, 1991;Latour et al, 2012;Raabe and Hightower, 2014). These factors all make management of American shad important.…”

Evaluation of Fish Passage at a Nature‐Like Rock Ramp Fishway on a Large Coastal River

“…However, we observed predation on one adult American Shad and one adult Striped Bass, which were consumed by Flathead Catfish (i.e., tail protruding from the gullet) that were sampled and tagged downstream of LD‐1. Flathead Catfish predation on American Shad has also been observed by Ashley and Buff () in the Cape Fear River and by Raabe and Hightower () in the Little River. Delays for American Shad can be especially detrimental in terms of energy loss, as they consume minimal food in rivers and are more likely to succumb to predation or harvest (Castro‐Santos and Letcher ; Raabe and Hightower ; Stich et al.…”

“…Flathead Catfish predation on American Shad has also been observed by Ashley and Buff () in the Cape Fear River and by Raabe and Hightower () in the Little River. Delays for American Shad can be especially detrimental in terms of energy loss, as they consume minimal food in rivers and are more likely to succumb to predation or harvest (Castro‐Santos and Letcher ; Raabe and Hightower ; Stich et al. ).…”

“…In addition, migratory delays at dams can lead to additional energy expenditures and areas of concentrated fish, increasing their vulnerability to starvation, predation, and harvest (Schilt ; Castro‐Santos and Letcher ; Raabe and Hightower , ). Dam removals are occurring more frequently, and they have increased connectivity (Burdick and Hightower ; Raabe and Hightower , ). However, removals can be controversial, or stakeholders may determine that a removal is impractical, such as when a dam is providing hydropower or a water source (Stanley and Doyle ).…”

Micro-and macro-plastics in marine species from Nordic waters

“…Fish can lose a lot of weight while spawning, for e.g. Twaite shad that can lose 30% (male) and 50% (females) of their body weight after spawning (Raabe & Hightower, 2014) and the spawning cycle affects fish feeding behaviour during certain periods, which again may impact the amount of plastic ingested.…”