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Striped Bass Juvenile Abundance Index

Between 2014 and 2015, the relative abundance of juvenile striped bass in the Chesapeake Bay increased. In Maryland waters, the abundance index rose from 4.06 to 10.67, which is approximately double the long-term average. In Virginia waters, the index rose from 11.37 to 12, which is about equal to average historic values.






April 16, 2014

Striped bass are a sought-after commercial and recreational catch and a key predator in the Chesapeake Bay food web. Andrew Turner from the National Oceanic and Atmospheric Administration (NOAA)/Versar explains why the fish is so unique. Learn more about striped bass in the Chesapeake Bay Program’s online Field Guide.

Closed Captions.

Importance

The Chesapeake Bay is one of the most important striped bass breeding habitats on the East Coast, supporting valuable commercial and recreational fisheries. To monitor the reproductive success of striped bass, scientists take annual seine net samples in noted spawning areas, which include the Choptank, Potomac and Nanticoke rivers in Maryland and the Rappahannock, York and James rivers in Virginia. The average number of young-of-the-year striped bass—or rockfish that are less than one year old—in each seine haul is known as the juvenile abundance index.

The abundance indices developed in Maryland and Virginia document the annual variation in striped bass year classes and help scientists evaluate the health of the striped bass stock. These indices also serve as early indicators of future adult fish abundance, helping managers predict the amount of adult fish that will be available for commercial and recreational fishermen.

Long-term trend (1967-2015)

Historically, periods of low abundance index values—which represent weak year classes with low recruitment success—are followed by a high index value—which represents a strong year class with high recruitment success. These strong year classes sustain the striped bass population following less productive years.

During the 1970s and early '80s, overharvesting kept abundance index values low in both Maryland and Virginia. In the late '80s, coast-wide and regional harvest restrictions were put in place that helped rebuild the stock.

In Maryland, juvenile striped bass abundance peaked in 1996 with an index value of 17.61 and reached its lowest point in 2012 with an index value of 0.49. In Virginia, juvenile striped bass abundance reached its lowest point in 1972 with an index value of 1.28 and peaked in 2011 with an index value of 27.09. Recruitment in Virginia has been average or above average in 12 of the past 13 years, indicating production has been relatively consistent in Virginia nurseries. The peaks and valleys seen in both states illustrate the varying success in striped bass recruitment in the Chesapeake Bay over time.

Short-term trend (2005-2015)

Index values reached notable highs in both Maryland and Virginia in 2011, indicating a strong striped bass year class and recruitment rate across the Chesapeake Bay. Indeed, Virginia’s 2011 peak of 27.09 is the highest index value either state has recorded since 1982. But index values declined in 2012, indicating a follow-up year of poor recruitment. Maryland’s 2012 value of 0.49 was the lowest either state has recorded since 1982, while Virginia’s value of 2.68 was its lowest since 1985. The past three years, however, have seen a rise in index values in both states.

Change from previous year (2014-2015)

Between 2014 and 2015, the relative abundance of juvenile striped bass in the Chesapeake Bay increased.

  • In Maryland waters, the abundance index rose from 4.06 to 10.67, which is approximately double the long-term average.
  • In Virginia waters, the abundance index rose from 11.37 to 12, which is about equal to average historic values.

Additional Information

It is important to note that this indicator does not estimate the actual abundance of juvenile striped bass in the Chesapeake Bay. In other words, the index values are only a measure of relative abundance, representing the average number of juvenile striped bass caught per seine haul in each year’s survey.

In 1973, a discontinuation of funding temporarily closed Virginia’s striped bass recruitment monitoring program. The program was reinstated in 1980, which explains the gap in the state’s data.

Learn more about how the juvenile striped bass survey is conducted in Maryland or Virginia.

Source of Data

Maryland Department of Natural Resources, Virginia Institute of Marine Science

410 Severn Avenue / Suite 112
Annapolis, Maryland 21403
Tel: (800) YOUR-BAY / Fax: (410) 267-5777
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