Early Life History of Blueback Herring and Alewife in the Lower Roanoke River, North Carolina

Abstract

Seasonal distribution, abundance, habitat use, hatch dates, growth, and mortality of larval blueback herring Alosa aestivalis and alewife A. pseudoharengus were studied in the Roanoke River watershed, downstream from the Roanoke Rapids Dam in North Carolina. Ichthyoplankton was sampled from man-made canals, a creek, an oxbow, a flooded bottomland hardwood forest, the main river channel, and along the river's edge. To identify larval clupeids, we developed a dichotomous key for clupeids found in the study area using morphometric, meristic, and pigmentation characters synthesized from the literature. Distribution, abundance, and back-calculated hatch dates of larvae and eggs were used to describe spawning period, spawning habitat, and nursery habitat. Blueback herring and alewife eggs and larvae were present from early April through late May. Based on the presence of eggs and early-stage larvae, both species spawned in backwater tributary systems, including flooded bottomland hardwood forests. Our results indicated that blueback herring and alewives used a variety of habitats during early larval stages, though interspecific differences in concentration among habitats were evident. Blueback herring used both lotic (moving water) and lentic (still water) habitats, and alewives were more abundant in lentic habitats. Larval growth varied between years but not between species. Blueback herring growth rates were 0.60 mm/d in 1996 and 0.42 mm/d in 1997 compared with growth rates of 0.65 mm/d in 1996 and 0.41 mm/d in 1997 for alewives. Interspecific and between-year differences in daily mortality of preflexion blueback herring and alewives (age, 4-8 d) were observed. Blueback herring daily percent mortality in 1996 and 1997 was 99%, while alewife rates decreased from 98% in 1996 to 91% in 1997. Fluctuations in river flow affected habitat use; moderate to high discharge rates increased use of spawning and nursery habitats, and low flows reduced use of spawning habitat.

Thermal tolerance of allis shad (Alosa alosa) embryos and larvae: Modeling and potential applications

“…data) and 4% for the American shad Alosa sapidissima (Savoy and Crecco 1988). Survival rates of larvae in the field are similarly low: 1% survival of blueback herring Alosa aestivalis larvae between 4 and 8 days post-hatching (Walsh et al 2005) and 2% survival of American shad larvae between 4 and 30 dph (Crecco et al 1983). In natural conditions, these low survival rates could be explained by combinations of numerous negative biotic or abiotic factors, such as river discharge, dissolved oxygen, prey availability and predation (Crecco and Savoy 1984;Crecco and Savoy 1985;Limburg 2001;Esteves and Andrade 2012).…”

Ichthyoplankton transport in relation to floodplain width and inundation and tributary creek discharge in the lower Savannah River of Georgia and South Carolina

“…Negative effects on larval recruitment have been hypothesized to include having reduced residence time in the nursery habitat portions of rivers due to washout at high flow rates (Meador et al, 1984;Mion et al, 1998) or increased turbidity from high flow events (Mion et al, 1998;Shoji et al, 2005). Positive effects include access to nursery and spawning areas in floodplain pools and other inundated habitat (Sabo & Kelso, 1991;Turner et al, 1994;Fontenot et al, 2001;King et al, 2003;Sommer et al, 2004;Walsh et al, 2005), reduced floodplain pool anoxia because of greater mixing (Fontenot et al, 2001), and the availability of flooded mouths of tributaries to species that require backwaters for spawning and nursery areas (Holland, 1986;Brown & Coon, 1994). Several species in the Savannah River, including American shad, striped bass and shortnose sturgeon Acipenser brevirostrum Lesueur, typically spawn in the main channel rather than the floodplain.…”

Population demographics of Hickory Shad (Alosa mediocris) during a period of population growth

“…The ASMFC has long identifi ed life history aspects and the stock status of Hickory Shad as priorities for future research (Richkus and DiNardo 1 ; ASMFC 11,12,13 (Rulifson and Manooch, 1991). The coastal plain portion of the watershed downstream of the last dam has an extensive fl oodplain that consists of hardwood forest, backwater swamps, oxbow lakes, and small creeks (Zincone and Rulifson, 1991), which are connected to the river by natural and anthropogenic openings in the natural river levee (Walsh et al, 2005).…”

“…Habitat loss and fragmentation, along with overharvesting the species, are considered major factors in the reduction of alosine stocks to remnant populations in this watershed (Walsh et al, 2005;McCargo et al 7 ) and elsewhere in the North Atlantic (Limburg and Waldman, 2009). Restoration of the American Shad population in the Roanoke River has been ongoing since 1988 (Waters 24 ), but adult abundance remains low despite the stocking of 43 million American Shad fry in the Roanoke River as of 2010 (Dockendorf 10 ).…”