Wintertime Occurrence of Fish in Tidal Deepwater Habitat of the Potomac River.

摘要

Hydroacoustic and trawl sampling were conducted in the Potomac River on 21-22 February 1990 to provide preliminary data on the use of deep-hole habitat by overwintering fishes. Hydroacoustic surveys were performed in three of the most prominent deep holes in the tidal region of the river. Then, trawl surveys and intensive hydroacoustic surveys were conducted at one of these sites, a deep-hole site below Dogue Creek, and a nearby main-channel site near Gunston Cove. Echograms from the hydroacoustic surveys showed that fish were present at all three deep-hole survey sites. At the intensively sampled areas, eight species of fish were collected by trawl from the deep hole and six from the main channel. White perch comprised more than 85 percent of the trawl catch at each site. Acoustically estimated fish densities were quite similar at the deep-hole (517 to 528 fish/acre) and main-channel (575 fish/acre) locations. However, fish were not uniformly distributed throughout the deep-hole site. In general, densities were lowest in the area immediately surrounding the deep hole, and they progressively increased in the shallower waters on the deep-hole side slope. This distribution pattern persisted for 2 days of sampling. Within the confines of a preliminary study, no evidence was found to indicate that deep holes in the Potomac River are more valuable overwintering habitat for fishes than are shallower main-channel areas. Bendway, Hydroacoustics, Scour holes, Dredged material disposal, Meander loops, Tidal, Fish, Morone chrysops, Trawl survey, Fish abundance, Potomac River, White perch, Fish density.