Area Sampled
In the spring of 1955, the survey sampled a series
of stations in the mid-river channel at approximately five-mile intervals
from the mouth of the York River to West Point, Virgina. Stations were sampled
irregularly for the rest of that year. Since April 1956, these stations have
been sampled almost continuously (April through November). A few stations
in lower Chesapeake Bay and in the Pamunkey River were regularly sampled for
several years. Historical photos of VIMS trawling
In
1962, sampling on the Rappahannock River commenced; stations on the James
River were added in 1964. Occasional samples were taken from the Potomac River,
Mobjack Bay, and several smaller tributaries. Semi-annual sampling of Chesapeake
Bay occurred sporadically until 1988 when regular sampling of the entire Virginia
portion of the Chesapeake Bay began.
Maps of trawl stations in a typical month of sampling with the current sampling scheme: Chesapeake Bay, York River , Rappahannock River, James River
Gear
The trawl gear has
been modified several times, affecting the kind and size of fish captured.
Extensive sampling using these various gear configurations was completed in
order to standardize the catch rate associated with each gear combination.
- A tickler chain, which stirs up the bottom and increases the catch of bottom-dwelling species such as blue crabs and flatfish, was added in 1973.
- A small mesh liner was added in 1979. This enabled the net to retain smaller species such as bay anchovy, as well as smaller individuals of other species.
- The doors, wings which pull the mouth of the
net open as it travels through the water, were changed in 1991. This change
did not significantly alter the catch.
Vessel
There have been a number of vessel changes thoughout
the history of the survey. Our current vessel, the R/V Fish Hawk, was purchased
in 1988.
Historical vessel and gear changes (1955-2005)
Catch
After each five-minute tow, the catch is sorted
and fishes are identified and measured then quickly returned to the water.
(Subsets of large catches are measured and the rest are counted.) Invertebrates
are identified and some are measured. Habitat type is also noted. Approximately
70 species are commonly caught, although more than 200 species have been identified
during the last 50 years. The species caught in
greatest abundance include bay anchovy, hogchoker, Atlantic croaker, spot,
white perch, weakfish, spotted hake, white catfish, silver perch and northern
sea robin.