ANNAPOLIS - The Maryland Department of Natural Resources (DNR) announced today that the 2006 striped bass (rockfish) juvenile index, a measure of striped bass spawning success in Chesapeake Bay, is 4.3, well below the 53-year average of 12.0. During this year’s survey, DNR biologists collected 561 young-of-year (YOY) striped bass.
Striped bass populations are well known for highly variable reproductive success from year to year. Typically, several years of average year-classes are interspersed with occasional large and small year-classes. Striped bass spawn in large numbers and individual females can produce millions of eggs to take advantage of favorable environmental conditions in some years. The survey has documented above average spawning success in three of the past six years (see chart).
Overall, reproduction of anadromous fish - those species that migrate into fresh water to spawn - was low this year, likely due to spring drought conditions. Similar drought conditions and low anadromous fish reproduction were observed in 2002. One notable exception this year occurred in the Potomac River, where biologists observed healthy numbers of juvenile American shad for the seventh consecutive year. Once the subject of a large commercial and recreational fishery, American shad are currently under a protective moratorium.
DNR biologists have monitored the reproductive success of striped bass and other species in Maryland’s portion of the Chesapeake Bay annually since 1954. Twenty-two survey sites are located in the four major spawning systems: The Upper Bay and the Choptank, Potomac and Nanticoke rivers. Biologists visit each site monthly from July through September, collecting fish samples with two sweeps of a 100-foot beach seine. The index is calculated as the average catch of YOY fish per sample.
RELATED INFORMATION:
Striped Bass Seine Survey - Juvenile Index Page
http://www.dnr.state.md.us/fisheries/juvindex/