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Juvenile striped bass abundance remains steady in Virginia waters

  • Juvenile Striped Bass Seine Survey   Crew members Daniel Royster (L) and PJ LeBel III (R) sort the survey catch on the Mattaponi River.   Jack Buchanan.
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by Staff |  October 15, 2021

Preliminary results from an ongoing long-term survey conducted by researchers at the Virginia Institute of Marine Science suggest another average year class of young-of-year striped bass was produced in Virginia tributaries of the Chesapeake Bay in 2021. The 2021 year class represents the group of fish hatched this spring that will grow to fishable sizes in three to four years.

The VIMS Juvenile Striped Bass Seine Survey recorded a mean value of 6.30 fish per seine haul in the Virginia portion of the Chesapeake Bay. The 2021 value—which scientists call a recruitment index—is similar to the historic average of 7.77 fish per seine haul and represents the 9th consecutive year of average or above-average recruitment in Virginia waters. Although there can be considerable variation in striped bass recruitment among years, the indices observed in recent years suggest that abundance of juvenile striped bass in Virginia has been relatively stable.

Crew members PJ LeBel III (L) and Ashleigh Thomas (R) seine for juvenile striped bass on the James River. © J. Buchanan/VIMS.

Striped bass play an important role as a top predator in the Chesapeake Bay ecosystem and are a valuable resource for commercial and recreational anglers. Professor Mary Fabrizio, who directs the Juvenile Striped Bass Seine Survey at VIMS, notes that the economic and ecological value of striped bass lends significant interest to the year-to-year status of their population. "By estimating the relative number of young-of-year striped bass," she says, "our survey provides an important measure of annual and long-term trends in the Bay's striped bass population."

The VIMS survey samples 18 index sites in the Rappahannock, York, and James River watersheds. Biologists sample each site 5 times from late June to late August, deploying a 100-foot seine net from the shore. Each fish captured in the net is counted, measured, and returned to the river. These young striped bass usually measure between 1.5 and 4 inches. Survey scientists in Virginia measured 1,512 juvenile striped bass at these stations in 2021. VIMS has been conducting the survey annually since 1967 for the Virginia Marine Resources Commission (VMRC).

Researcher Jack Buchanan measures the seine catch on the Rappahannock River. © S. Dowiarz/VIMS..The striped bass population in Chesapeake Bay has rebounded from historic lows in the late 1970s and early 1980s after fishing bans were enacted in Delaware, Maryland, and Virginia in the mid- to late-1980s. Since then, the population increased to the point that striped bass in the Bay and elsewhere were considered recovered. In 2019, scientists determined that the coast-wide striped bass population was overfished and that mortality due to fishing was higher than what the population can withstand in the long term. Monitoring of juvenile striped bass recruitment will continue next year to provide managers with crucial information to sustainably manage this important species.

The Maryland Department of Natural Resources (MDNR) conducts a similar survey within Maryland’s portion of the Chesapeake Bay. In 2021, MDNR recorded a below-average year class. Differences between Maryland and Virginia indices are not uncommon. For example, in 2013, 2016, 2019, and 2020, MDNR recorded below-average year classes in Maryland, while VIMS recorded average or above-average year classes in Virginia. The causes of such differences vary annually and can be difficult to determine. Striped bass populations, however, are supported by strong year classes which can mitigate the impact of less productive years.

Index (scaled geometric mean) of young-of-the-year striped bass in the primary nursery areas of Virginia by year. Vertical bars are 95% confidence intervals as estimated by +/- 2 standard errors of the mean. Horizontal lines indicate the arithmetic mean (thin solid line) and confidence intervals on the mean (dashed lines) estimated from indices observed in the historic reference period (1980-2009). An annual index value is considered “average” when its confidence intervals fall within the confidence intervals that surround the long-term mean. Significant differences exist when confidence intervals do not overlap.