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Striped Bass Juvenile Abundance Index

Between 2013 and 2014, the relative abundance of juvenile striped bass in the Chesapeake Bay increased. In Maryland waters, the abundance index rose from 3.42 to 4.06. In Virginia waters, the index rose from 10.92 to 11.37. These index values are about equal to the average historic values in each state, and are a significant increase from the low recruitment seen in the region in 2012. 






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.

Produced by Steve Droter
Music: “A Moment of Jazz” by Ancelin

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. 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 (1967-2014)

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. 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 (2004-2014)

Over the last decade, index values peaked in both Maryland and Virginia in 2011. This indicates a strong striped bass year class and recruitment rate across the Chesapeake Bay. Indeed, Virginia’s 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 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 two years have seen a slight rise in index values in both states.

Change from previous year (2013-2014)

Between 2013 and 2014, the abundance of juvenile striped bass in the Chesapeake Bay increased. In Maryland, the abundance index rose from 3.42 to 4.06. In Virginia, the index rose from 10.92 to 11.37. These index values are about equal to the historic values in each state, and are a significant increase from the low recruitment seen in the region in 2012.

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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