Sharks of Onslow County
Each November, when highways fill with travelers heading home for Thanksgiving, the waters of Onslow County’s New River Estuary host a quieter kind of migration. Beneath the surface, schools of silvery menhaden, golden spot, croaker, and even small sharks begin the New River Inlet fish migration, drawn by instincts older than any holiday tradition. The tides quicken. Water cools. Marsh grasses brown and whisper in the wind. And with every falling tide, the river seems to breathe outward, carrying its pilgrims toward the sea.
New River Inlet is not simply a passage between Sneads Ferry and North Topsail Beach—it is a living threshold.
As autumn advances, the estuary’s chemistry shifts: cooler water holds more oxygen, salinity rises with lower rainfall, and winds begin steering surface currents southward. These changes open a corridor that hundreds of thousands of fish follow instinctively from the creeks to the ocean shelf.
For species like spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus), this downstream journey completes the first half of a circular life cycle. After spending spring and summer feeding in the calm nurseries of the estuary, they now join the coastal current to overwinter in deeper, warmer water—traveling the same path their parents once took (Odell et al., 2017).
This path is more than instinct. It follows the physical architecture of the river itself—the deep, tidally flushed channels that connect Stones Bay and the main river to the inlet’s thalweg. When autumn winds push water seaward, these channels become a hydrodynamic migration corridor, a natural conveyor that funnels fish from the upper river toward the mouth (Odell et al., 2017).
The inlet becomes a moving parade: ripples flashing silver, gulls diving, and every outgoing tide pulling another wave of life toward the horizon.
Among the first to leave are Atlantic menhaden (Brevoortia tyrannus), the shimmering filter-feeders that fuel much of the coastal food web. Juveniles spend the warmer months feeding in the upper river, turning sunlight and plankton into pure energy. When the water dips below 18 °C, they form tight schools and funnel through the inlet, their bodies reflecting the low winter sun like coins scattered across the tide.
Studies of otolith chemistry show that these migrants come from multiple estuarine nurseries along the Atlantic seaboard, each contributing recruits to the coast-wide population (Anstead et al., 2016). Their exodus through the New River Inlet is not just a local event—it’s part of a continental rhythm that keeps the Atlantic alive.
Beyond the inlet, menhaden rarely swim straight into the deep. Instead, they travel through the nearshore transition zone, staying within roughly 10 kilometers of the coast, guided by southward longshore currents driven by seasonal winds (Lozano et al., 2013). Here they join massive coastal schools that drift toward Cape Fear and beyond, remaining within waters of 12–18 °C—their preferred thermal band. Each year, these moving rivers of fish carry the New River’s energy down the Atlantic coast like a living current of light.
Close behind move the “drums”—spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus)—so named for the sound they make vibrating muscles against their swim bladders. By late autumn, they too feel the pull of the current. Their bodies, now heavy from a summer of estuarine abundance, drift downstream in schools that seem to hum with the low percussion of their name.
In coastal surveys, researchers have traced these migrations from estuarine creeks to the continental shelf, where the fish spend the winter in relative warmth before returning north in spring (Odell et al., 2017). In ecological terms, it’s an energy transfer: the nutrients once locked in the mud and detritus of the New River now exported to the open sea.
Once through the inlet, spot and croaker follow two primary routes—some hugging the coast within the surf zone, others settling on the inner continental shelf at 15–35 meters depth. They drift southward along the Carolina Coastal Current, a steady, wind-driven flow that connects Onslow Bay to warmer waters off South Carolina and Georgia. Beneath the surface, these fish form vast, undulating layers—millions of tiny drummers keeping rhythm with the season.
Following the smaller fish come the quiet shadows—juvenile coastal sharks moving through the inlet on their own pilgrimage. Tagging studies across North Carolina reveal that blacktip, sandbar, and bull sharks use shallow estuarine margins as summer nurseries before shifting offshore in late fall when the water cools (Bangley et al., 2018; Rulifson & Bangley, 2015).
In the turbid water at the inlet’s mouth, these young predators trace invisible highways along sandbars and channels, following the scent of prey schools that have already departed. Many continue to ride the same southward current as the drum and menhaden but at greater depth—sometimes reaching the outer continental shelf (30–80 meters) where the water remains above 18 °C. For a few short weeks, river and sea mingle in one shared migration—prey, predator, and current moving together through the same watery passage.
The departure is not random. Temperature, daylight, and shifting prey availability synchronize this movement. When shrimp and plankton thin in the creeks, the fish follow the energy gradient seaward. In doing so, they maintain the seasonal connectivity that defines an estuary’s health: nutrients exported from the marsh become the foundation of offshore food webs, feeding mackerel, tuna, and seabirds far beyond the New River’s mouth (Lozano et al., 2013).
This corridor of movement also depends on the forces of wind and tide. During late fall, northwest winds push surface waters offshore through Ekman transport, enhancing the ebb flow that draws fish outward. Each tide functions as a breath of the estuary—an exhalation of life—carrying energy from the marshes to the sea (Odell et al., 2017).
This is the river’s gift to the ocean—the annual offering that ensures what leaves the estuary returns as new life months later.
If seen from above, the late-autumn water resembles a conveyor of light: streaks of silver menhaden, bronze drum, and dark shark fins blending into the green-blue inlet plume. Each species is a pilgrim, carried by tides instead of highways, guided by magnetic fields instead of maps. Their departure is as old as the coastline itself—a Thanksgiving procession written in currents and instincts rather than calendars. For those standing on the dunes at North Topsail Beach, the scene feels both ancient and immediate: the hush of wind, the roll of the tide, and somewhere beneath, the silent travelers heading home.
Anstead, K. A., Schaffler, J. J., & Jones, C. M. (2016). Coast-wide nursery contribution of new recruits to the population of Atlantic menhaden. Transactions of the American Fisheries Society, 145(3), 627–636. https://doi.org/10.1080/00028487.2016.1150345
Bangley, C. W., Paramore, L., Dedman, S., & Rulifson, R. A. (2018). Delineation and mapping of coastal shark habitat within a shallow lagoonal estuary. PLOS ONE, 13(4), e0195221. https://doi.org/10.1371/journal.pone.0195221
Lozano, C. J., Houde, E. D., & Severin, K. P. (2013). Factors contributing to variability in larval ingress of Atlantic menhaden (Brevoortia tyrannus) to Chesapeake Bay. Estuarine, Coastal and Shelf Science, 118, 1–10. https://doi.org/10.1016/j.ecss.2012.12.018
Odell, J., Adams, D. H., Boutin, B., Collier, W., Deary, A., Havel, L. N., Johnson, J. A. Jr., Midway, S. R., Murray, J., Smith, K., Wilke, K. M., & Yuen, M. W. (2017). Atlantic Sciaenid habitats: A review of utilization, threats, and recommendations for conservation, management, and research (Habitat Management Series No. 14). Atlantic States Marine Fisheries Commission. https://asmfc.org/wp-content/uploads/2024/12/HMS14_AtlanticSciaenidHabitats_Winter2017.pdf
Rulifson, R. A., & Bangley, C. W. (2015). Quantifying estuarine habitat use by multiple coastal shark species (NOAA Technical Report). NOAA Institutional Repository. https://repository.library.noaa.gov/view/noaa/46115
