VIMS

Juvenile striped bass maintain average abundance in Virginia waters in 2018

  • 2018 Striped Bass Seine Survey Crew
    2018 Striped Bass Seine Survey Crew  From L: Brian Gallagher, Emelia Marshall, and Matt Oliver—field crew for VIMS' 2018 Juvenile Striped Bass Seine Survey—retrieve a seine net from a sampling site on the James River.  © D. Malmquist/VIMS.
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Preliminary results from an ongoing long-term survey conducted by researchers at the Virginia Institute of Marine Science suggest an average year class of young-of-year striped bass was produced in Virginia tributaries of the Chesapeake Bay in 2018. The 2018 year class represents the group of fish hatched this spring that can grow to fishable sizes in three to four years, if not claimed by natural mortality.

The program, formally known as the Juvenile Striped Bass Seine Survey, recorded a mean value of 10.72 fish per seine haul in the Virginia portion of Chesapeake Bay, which is similar to the historic average of 7.77 fish per seine haul. The 2018 value—which scientists call a recruitment index—was also similar to indices observed in the past five years. Although there can be considerable variation in striped bass recruitment among years, the average indices observed in recent years suggests that abundance of juvenile striped bass has been stable.

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. Field assistants Matt Oliver and Emelia Marshall prepare to measure water temperature and salinity at their sampling site for juvenile striped bass on the James River. © D. Malmquist/VIMS."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 Juvenile Striped Bass Seine Survey currently samples 18 index stations in the Rappahannock, York, and James River watersheds. Biologists sampled each site 5 times from late June to early September in 2018, deploying a 100-foot seine net from the shore. Each fish captured in the net is counted, measured, and returned to the water. These young striped bass usually measure between 1.5-4 inches long. Brian Gallagher, chief scientist for the Juvenile Striped Bass Seine Survey at VIMS, examines the haul from a tow in the James River. © D. Malmquist/VIMS.Survey scientists in Virginia measured 1,875 juvenile striped bass at these stations in 2018. VIMS has been conducting the survey annually since 1967 for the Virginia Marine Resources Commission (VMRC). The Maryland Department of Natural Resources conducts a similar survey in the northern portion of the Bay.

The striped bass population in the 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 has increased to the point that striped bass in the Bay and elsewhere are now considered recovered. Monitoring of juvenile striped bass recruitment will continue next year to provide managers with crucial information to sustainably manage this important species.

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). Significant differences exist when confidence intervals do not overlap.