October-November 2009

The onset of cooler temperatures encourages many of the legal-sized individuals of some sought-after species to migrate out of Chesapeake Bay into the coastal ocean. This is evidenced by the decrease in numbers of large summer flounder and Atlantic croaker captured by the crew of the Virginia Institute of Marine Science's (VIMS) Juvenile Fish Survey during October and November. Only a handful of large croaker (13 to 14 inch) were measured during the last two months. These fish were captured in the lower York River and the middle and lower Rappahannock River. A similar scenario holds true for summer flounder with only a few fish in the 19- to 23-inch range measured during the last two months of the survey. The largest of these fish were measured in October from the mouth of the James River and in the Rappahannock River near Towles point.

A species whose larger individuals remain in the area is white perch. Perch in the 9- to 10- inch range were measured from the middle Rappahannock River near Greenvale Creek and the middle and upper York River from Purtan Island upstream to Lee Marsh in both October and November.

Although water temperatures have dropped, we continue to encounter a number of interesting but uncommon species for Chesapeake Bay. Some of the uncommon species encountered recently are Atlantic bumper, chain pipefish, bluespotted cornetfish, and planehead filefish. Planehead filefish are one of three species of filefish present in Chesapeake Bay but are rarely encountered by the Trawl Survey with only two individuals recorded since 2000. Filefish are closely related to and resemble triggerfish but can be readily separated by the presence of a long and prominent dorsal spine. Planehead filefish also have a prominent pelvic spine, which the two other species of filefishes occurring in Chesapeake Bay do not possess. Planehead filefish feed on bryozoans, urchins and small crustaceans in addition to small mollusks and algae. In the western Atlantic Ocean planehead filefish occur from Nova Scotia south to Brazil.

For more information about this ongoing monthly survey visit the Juvenile Fish Survey web page.