Variability typical of striped bass populations
Maryland Department of Natural Resources (DNR) Fisheries Service Director Eric J. Schwaab announced today that the 2002 striped bass (rockfish) juvenile index is 4.7. The long-term average is 11.6.
“Striped bass populations have highly variable reproductive success from year to year, with several years of average year-classes interspersed with occasional large and small year-classes,” said Fisheries Service Director Eric C. Schwaab. “It is not uncommon for a dominant year-class, such as 2001, to be followed by a below-average year class. However, we will continue to monitor the data to discern long-term trends.
During this year’s survey, DNR biologists collected 624 young-of-year (YOY) striped bass. Reproduction in the Potomac and Nanticoke rivers was near average, with indices of 7.0 and 7.8, respectively. The Upper Bay index of 3.1 was well below its long-term average. The Choptank River index of 0.7 was the lowest of all areas sampled.
Overall, reproduction of anadromous fish — those species that migrate into fresh water to spawn — was low in 2002, perhaps due to drought conditions. One notable exception occurred in the Potomac River, where biologists documented near-record numbers of juvenile American shad. 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 in Maryland’s portion of the Chesapeake Bay annually since 1954. Twenty-two survey sites are located in the four major spawning systems: Choptank, Potomac, and Nanticoke rivers, and the Upper Bay. 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 striped bass per sample.
Posted: 10-23-2002
