Survey Methods
Area Sampled
Currently, the survey samples waters from 18 historically sampled sites (index stations) and 22 auxiliary stations along the shores of the James, Chickahominy, Appomattox, York, Pamunkey, Mattaponi, and Rappahannock rivers. The addition of the auxiliary sites was made to provide better geographic coverage and, once a sufficient time series of data is developed, to create larger sample sizes within river systems so that trends in juvenile abundance can be meaningfully monitored on a system-by-system basis.
Field sampling is conducted during five, approximately biweekly, sampling periods ("rounds") from June or July through September. Each site is sampled once per round, for each of the five rounds of sampling conducted each summer.
Gear
The Juvenile Striped Bass Seine Survey originally used a 6 foot x 100 foot x 0.25 inch (2 meters x 30.5 meters x 0.64 centimeters) mesh-bag seine. However, comparison tows with Maryland Juvenile Striped Bass Survey gear, a 4 foot x 100 foot x 0.25 inch (1.22 meters x 30.5 meters x 0.64 centimeters) beach seine, showed no statistical differences in catch. Virginia adopted the "Maryland seine" in 1986.
Net Deployment and Retrieval
At each station, collections are done by deploying the seine net perpendicular to the shoreline (either until the net is fully extended or a depth of approximately 4 feet is encountered), leaving the onshore brail in a fixed position while another person pulls the offshore brail downcurrent and back to the shore, resulting in the sweeping of a quarter-circle quadrant.
Data Collection
At index stations, the net is pulled twice, allowing 30 minutes between tows to allow the site to settle again. At each station, all Striped Bass, and a sub-sample of at least 25 individuals each of other species, are measured to the nearest millimeter fork length (or total length if appropriate) using an electronic measuring board. All fishes captured, except those preserved for life history studies, are returned back to the water at the conclusion of sampling at each site. Counts are taken of other species after 25 individuals are measured.
Environmental and station data are also recorded at each site. A water quality sonde collects salinity, water temperature, pH, and dissolved oxygen. A secchi disk, wind meter, and thermometer collect turbidity, wind speed, and air temperature. Other data collected includes tidal stage, weather and water surface conditions, and sampling time(s).