Migration and Spawning of American Shad in the James River, Virginia

Aunins, Aaron W.; Olney, John E.

doi:10.1577/t08-160.1

Cited by 25 publications

(31 citation statements)

References 14 publications

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“…Other American shad, however, occupied sites farther downstream throughout the spawning season, providing further evidence that multiple spawning sites exist in the Pee Dee River. Aunins and Olney (2009) observed three distinct areas of use in the James River, Virginia, and some of the tagged American shad did not migrate as far upstream as others. Similar to other studies, most American shad in the Pee Dee River remained in a discrete area for at least 20 d after they arrived on the spawning grounds (Beasley and Hightower 2000;Hightower and Sparks 2003;Olney et al 2006;Aunins and Olney 2009).…”

Section: Discussionmentioning

confidence: 92%

“…Our plankton and tracking data indicate that there are multiple discrete spawning areas, which are presumably based on habitat. The observation of multiple discrete spawning sites within a river has been made for other American shad populations (Layzer 1974;Aunins and Olney 2009). Our daytime sampling only extended as far downstream as Bluff (rkm 129) and our nighttime sampling only occurred as far downstream as Society Hill (rkm 237), so additional spawning sites potentially exist.…”

Section: Discussionmentioning

confidence: 99%

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Identification of American Shad Spawning Sites and Habitat Use in the Pee Dee River, North Carolina and South Carolina

Harris¹,

Hightower²

2011

N American J Fish Manag

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We examined spawning site selection and habitat use by American shad Alosa sapidissima in the Pee Dee River, North Carolina and South Carolina, to inform future management in this flow‐regulated river. American shad eggs were collected in plankton tows, and the origin (spawning site) of each egg was estimated; relocations of radio‐tagged adults on spawning grounds illustrated habitat use and movement in relation to changes in water discharge rates. Most spawning was estimated to occur in the Piedmont physiographic region within a 25‐river‐kilometer (rkm) section just below the lowermost dam in the system; however, some spawning also occurred downstream in the Coastal Plain. The Piedmont region has a higher gradient and is predicted to have slightly higher current velocities and shallower depths, on average, than the Coastal Plain. The Piedmont region is dominated by large substrates (e.g., boulders and gravel), whereas the Coastal Plain is dominated by sand. Sampling at night (the primary spawning period) resulted in the collection of young eggs (≤1.5 h old) that more precisely identified the spawning sites. In the Piedmont region, most radio‐tagged American shad remained in discrete areas (average linear range = 3.6 rkm) during the spawning season and generally occupied water velocities between 0.20 and 0.69 m/s, depths between 1.0 and 2.9 m, and substrates dominated by boulder or bedrock and gravel. Tagged adults made only small‐scale movements with changes in water discharge rates. Our results demonstrate that the upstream extent of migration and an area of concentrated spawning occur just below the lowermost dam. If upstream areas have similar habitat, facilitating upstream access for American shad could increase the spawning habitat available and increase the population's size. Received March 22, 2011; accepted July 14, 2011

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Identification of American Shad Spawning Sites and Habitat Use in the Pee Dee River, North Carolina and South Carolina

Harris¹,

Hightower²

2011

N American J Fish Manag

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“…Sampling efforts were focused within the James River because it supports dense populations of large Blue Catfish and Flathead Catfish (Harris and Jones 2008;Greenlee and Lim 2011) and once supported large Alosa spp. migrations (Aunins and Onley 2009;Hilton et al 2011). Blue Catfish and Flathead Catfish were collected in the James River from March to May, as these months corresponded with the spring spawning movements of Blueback Herring, Alewives, and American Shad within the Chesapeake Bay (Garman and Nielsen 1992;Hewitt et al 2009;Hilton et al 2011).…”

Section: Methodsmentioning

confidence: 99%

Predation and Prey Selectivity by Nonnative Catfish on Migrating Alosines in an Atlantic Slope Estuary

et al. 2017

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Native to the central USA, the Blue Catfish Ictalurus furcatus and the Flathead Catfish Pylodictis olivaris have been widely introduced into many Atlantic slope rivers and are now found in several drainages of the Chesapeake Bay. Fisheries managers are concerned that these large, long‐lived catfish species may be contributing to observed declines in anadromous species, such as the American Shad Alosa sapidissima, Blueback Herring A. aestivalis, and Alewife A. pseudoharengus, all of which once comprised major U.S. fisheries. We assessed spatiotemporal variability and selectivity in the diets of Blue Catfish and Flathead Catfish during the spawning migration of these alosines. Catfish stomachs were collected during March–May in nontidal freshwater, tidal freshwater, oligohaline, and mesohaline portions of the James River. Diet contents were extracted from 2,495 catfish, 69.86% of which had prey items present in their foreguts (N = 1,743). We used DNA barcoding to identify degraded fish prey; nearly 30 taxa that would have otherwise gone undetected were identified in this manner. Blue Catfish had broad, omnivorous diets, whereas Flathead Catfish fed solely on other fish. Alosines were found in 4.46% of Blue Catfish stomachs and 16.67% of Flathead Catfish stomachs. Flathead Catfish selectively preyed on American Shad and, to a lesser degree, river herring. Alosines were consumed more frequently in nontidal freshwater areas, particularly in the high‐gradient reach between Bosher Dam and the 14th Street Bridge, and predation on alosines peaked in April. Our results suggest that Flathead Catfish are likely to have a greater per capita impact on depleted alosines. Furthermore, dams and other obstacles to fish movement may increase alosines’ vulnerability to predation by large catfish.

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“…It is possible that survival above the dams is higher than it is in the lower river but that out-migration delays, especially combined with turbine mortality, are resulting in an apparent reduction in survival. Aunins and Olney (2009) suggest that the survival of American shad hatched above Bosher's Dam in the James River, Virginia, appears to be much higher than the survival of those below the dam. Hatcheryreleased, OTC-marked American shad over 1 year in age have been collected in upper Roanoke River basin reservoirs, which indicates that some survive despite not reaching the ocean.…”

mentioning

confidence: 91%

Demographic Population Model for American Shad: Will Access to Additional Habitat Upstream of Dams Increase Population Sizes?

Harris

Hightower

2012

Mar Coast Fish

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American shad Alosa sapidissima are in decline in their native range, and modeling possible management scenarios could help guide their restoration. We developed a density-dependent, deterministic, stage-based matrix model to predict the population-level results of transporting American shad to suitable spawning habitat upstream of dams on the Roanoke River, North Carolina and Virginia. We used data on sonic-tagged adult American shad and oxytetracycline-marked American shad fry both above and below dams on the Roanoke River with information from other systems to estimate a starting population size and vital rates. We modeled the adult female population over 30 years under plausible scenarios of adult transport, effective fecundity (egg production), and survival of adults (i.e., to return to spawn the next year) and juveniles (from spawned egg to age 1). We also evaluated the potential effects of increased survival for adults and juveniles. The adult female population size in the Roanoke River was estimated to be 5,224. With no transport, the model predicted a slow population increase over the next 30 years. Predicted population increases were highest when survival was improved during the first year of life. Transport was predicted to benefit the population only if high rates of effective fecundity and juvenile survival could be achieved. Currently, transported adults and young are less likely to successfully out-migrate than individuals below the dams, and the estimated adult population size is much smaller than either of two assumed values of carrying capacity for the lower river; therefore, transport is not predicted to help restore the stock under present conditions. Research on survival rates, density-dependent processes, and the impacts of structures to increase out-migration success would improve evaluation of the potential benefits of access to additional spawning habitat for American shad.

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Migration and Spawning of American Shad in the James River, Virginia

Cited by 25 publications

References 14 publications

Identification of American Shad Spawning Sites and Habitat Use in the Pee Dee River, North Carolina and South Carolina

Identification of American Shad Spawning Sites and Habitat Use in the Pee Dee River, North Carolina and South Carolina

Predation and Prey Selectivity by Nonnative Catfish on Migrating Alosines in an Atlantic Slope Estuary

Demographic Population Model for American Shad: Will Access to Additional Habitat Upstream of Dams Increase Population Sizes?

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