Striped bass spawning success has improved in the Chesapeake Bay, according to scientists from both Maryland and Virginia.
Tracking the number of young-of-the-year striped bass in the Bay, or those rockfish that are less than one year old, helps scientists evaluate the health of the striped bass stock. To determine this number, scientists take a series of seine net samples in select striped bass spawning areas—like the Choptank, Potomac and Nanticoke rivers in Maryland and the Rappahannock, York and James rivers in Virginia—each summer. The resulting “juvenile abundance index” serves as an early indicator of future fish populations, helping managers predict the amount of striped bass that will be available to fishermen in the coming years.
“Striped bass are a… resilient species when given favorable environmental conditions for reproduction and survival,” said Maryland Department of Natural Resources Secretary Mark Belton in a media release. “The robust reproduction should give Maryland anglers hope for a successful striped bass season in a few years’ time.”
In each Maryland sample, researchers caught an average of 24 juvenile striped bass; the state’s abundance index value rose from 4.06 to 10.67 this year, which is the eighth highest on record. In each Virginia sample, researchers caught an average of 12 juvenile striped bass; the Commonwealth’s abundance index value rose from 11.37 to 12, which is about equal to average historic values. There, striped bass spawning success has been average or above average in 12 of the last 13 years, which indicates consistent production in Virginia nurseries.
Striped bass hold great value in the watershed: the fish is a top predator in the food web and a critical catch for commercial and recreational fishermen. Fishing bans set in the late 1980s helped striped bass recover from harvest and pollution pressures, and experts now consider it a recovered species.
Striped bass spawning success has improved in the Chesapeake Bay.
Image courtesy randychiu/Flickr
According to data from the Maryland Department of Natural Resources (DNR) and the Virginia Institute of Marine Science (VIMS), the number of juvenile striped bass in the watershed has rebounded from last year, when it was close to the lowest ever observed.
Known as the “juvenile striped bass index,” the number of young-of-the-year striped bass in the Bay is used to track the species’ reproductive success. To count the number of striped bass that hatched this spring, biologists take a series of seine net samples in noted spawning areas, from the Upper Bay to the James River.
Image courtesy VIMS
This year, the average number of juvenile striped bass caught in each Maryland sample was 5.8, which falls below the 11.7 average but above last year’s index of less than one. In Virginia waters, researchers caught more than 10 striped bass per seine sample, which is close to the historic average of 9. A VIMS media release called the results consistent with historically observed patterns in striped bass populations.
Striped bass, or rockfish, hold great value in the watershed: the fish is a top predator in the food web and a critical catch to commercial and recreational fisheries. Late-1980's fishing bans helped striped bass recover from harvest and pollution pressures, and it is now considered a recovered species.
Striped bass spawning success is at an all-time low in the Chesapeake Bay.
Image courtesy Eddie Welker/Flickr
To track striped bass reproduction rates, biologists take a series of summer seine net samples at more than 20 sites in four striped bass spawning areas. This year, the average number of juvenile striped bass caught in each sample was 0.9. Last year’s juvenile striped bass index was 34.58; the long-term average is 12.
Biologists have blamed unfavorable weather for the decline.
“Generally, warm winters and dry springs are unfavorable conditions for fish that return to freshwater to spawn,” said DNR Striped Bass Survey Project Leader Eric Durrell. Like the striped bass, white perch, river herring and other anadromous fish also experienced low reproductive success this year.
But biologists “do not view this low value as an imminent problem,” said DNR Fisheries Director Tom O’Connell. “Three consecutive years of poor reproduction would be necessary to trigger mandatory conservation measures.”
According to the 2011 Striped Bass Stock Assessment released by the Atlantic States Marine Fisheries Commission, striped bass along the Atlantic coast are not overfished and overfishing is not occurring.