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.
Biologists with the Maryland Department of Natural Resources (DNR) recorded the fourth highest success rate for striped bass spawning in the Chesapeake Bay in 58 years, according to the 2011 Young of the Year Striped Bass Survey.
The survey figure of 34.6 is well above the long-term average of 11.9 and 2010’s 5.9. Striped bass spawning success varies from year to year due to factors such as water temperature, winter snowfall, spring river flow rates and weather conditions. The strong 2011 figure shows that when conditions are right, striped bass are capable of producing a large population of young.
During the 2011 survey, DNR biologists counted 47 different species among the more than 59,000 fish collected at 22 sites in the upper Bay and on the Choptank, Potomac and Nanticoke rivers. The survey also documented an increase in the abundance of juvenile blueback herring, a species that had decreased dramatically, and white perch, another important food and sport species.
Visit Maryland DNR’s website for more information about the striped bass spawning survey.
New tests by the Maryland Department of the Environment (MDE) show lower levels of contaminants in the Chesapeake Bay’s striped bass (rockfish), prompting the agency to increase its recommendation for the amount of the popular fish residents can safely eat.
Revised fish consumption advisories increase the recommended meal limits for striped bass caught in the Bay for nearly every population group.
The recommended meal limits for the general population for smaller striped bass increased by 50 percent, from two meals to three meals per month
The advisories no longer include the recommendation that had existed for women and children for certain striped bass
The new recommendations stem from recent test results that show a significant decline in PCB levels in striped bass from Maryland waters. Median PCB levels fell by more than half in fish analyzed between 2001-2005 versus in 2009-2010.
Data also suggest that contaminant levels are even lower in striped bass fillets prepared without fatty portions of the fish.
“Contamination has decreased in the striped bass we tested,” said MDE Acting Secretary Robert M. Summers. “Although we do not have the data to identify a specific explanation for the decline, PCBs have been banned in the United States since 1979, and we’re encouraged by this positive indication of the improving quality of our waters.”
MDE has also released new consumption advisories for bluefish caught in the Bay. Based on new data, MDE recommends a limit of two meals per month for bluefish less than 15 inches long. Residents should avoid eating bluefish larger than 15 inches.
Fish consumption advisories provide recommended limits on how often certain fish can be eaten and still enjoy health benefits while minimizing risks. For Maryland waters, fish consumption advisories are available on MDE’s website and posted at many public fishing areas.
For more information about the revised striped bass consumption advisory, including detailed consumption advisory charts, visit MDE’s website.
Welcome to the latest installment of the BayBlog Question of the Week! Each week, we take a question submitted on the Chesapeake Bay Program website or a frequently asked question and answer it here for all to read.
This week’s question came from Larry, who asked, “Do female striped bass feed while spawning?”
This question has an interesting -- but brief -- answer. In May 2006 the Delaware Department of Natural Resources and Environmental Control published research on striped bass food habits. Through a method called gastric lavage, the DNREC Division of Fish and Wildlife determined that female striped bass seem to eat very little just before spawning. Even the largest female striped bass ever caught during their spawning stock sampling (pictured in the link above) had an empty stomach when studied. This seems to be a trend for most striped bass during the spawning season.
Do you have a question about the Chesapeake Bay? Ask us and we might choose your question for the next Question of the Week! You can also ask us a question via Twitter by sending a reply to @chesbayprogram! Be sure to follow us there for all the latest in Bay news and events.
The number of young striped bass in Maryland waters in 2010 was below average for the third straight year, while in Virginia the amount of young striped bass was once again above average, according to juvenile striped bass surveys by the Maryland Department of Natural Resources (DNR) and the Virginia Institute of Marine Science (VIMS).
In Maryland, samplers collected an average of 5.6 young striped bass per haul, below the long-term average of 11.6 fish per haul. This is the third consecutive year of below average striped bass production in Maryland’s portion of the Chesapeake Bay.
In Virginia, nine fish were collected per haul, compared with the historic average of 7.5 fish per haul. Striped bass stocks in Virginia have exhibited average or above average recruitment since 2003.
Each summer, biologists monitor how successful striped bass reproduction was the previous spring by collecting fish samples from major striped bass spawning areas. In Maryland, biologists sample 22 survey sites on the Choptank, Potomac and Nanticoke rivers and in the upper Chesapeake Bay, while in Virginia, biologists sample at 18 stations on the York, James and Rappahannock rivers.
To sample an area, biologists deploy a 100-foot-long seine net from the shore and count all of the fish species collected in the net. The number of striped bass collected at these sites provides an estimate of how successful striped bass spawning was during the current year. This is important because as much as 90 percent of the Atlantic striped bass population may use the Chesapeake Bay as a spawning and nursery area.
Biologists with Maryland DNR say it is normal for the success of annual spawning to vary because striped bass reproduction is influenced by water temperature, winter snowfall, spring flow rates, weather conditions and many other factors.
Despite state-by-state variations, the striped bass population remains above the management action trigger set by the Atlantic States Marine Fisheries Commission (ASMFC). Likewise, the number of adults in the Atlantic coast population and levels of fishing are well within healthy limits as set by the ASMFC.
The number of young-of-the-year striped bass – fish that are less than one year old – found in the Maryland portion of the Chesapeake Bay in 2009 was up from last year but still a bit below average, according to the Maryland Department of Natural Resources (DNR) 2009 Young-of-the-Year Striped Bass Survey.
The survey found 7.9 young-of-the-year striped bass per haul, which is double that of last year, but still below the long-term average of 11.7.
“These numbers may be slightly below the average, but it’s well within the normal range of expectations,” said DNR Fisheries Service Director Tom O’Connell.
Striped bass, also known as rockfish or stripers, are one of the top predators in the Chesapeake Bay food web. Since they depend on large quantities of prey for survival and are affected by several other environmental factors, it is entirely normal for there to be spikes and dips in the yearly average.
This year’s index of young striped bass, in combination with record-setting classes like 1996, 2001 and 2003, helps to strengthen the once-struggling striped bass population in the Chesapeake Bay.
DNR biologists have monitored the reproductive success of rockfish and other species in Maryland’s portion of the Bay annually since 1954. They survey 22 sites located in the Choptank, Potomac and Nanticoke rivers and the upper Bay, which are the four major spawning areas for striped bass. Biologists check each site monthly from July to September by sweeping the area with a large net and counting all the fish collected in the net.
This year’s survey led to the identification of more than 35,000 fish from 49 different species. Of those, 1,039 were young-of-year striped bass.
For more information about the 2009 Young-of-the-Year Striped Bass Survey, visit DNR’s Striped Bass Survey website.