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Case: Chalk Point, MD

December 2000

Study Summary: Fish Community

In the wake of the April 2000 Potomac Electric Power Company (PEPCO) pipeline oil spill near Benedict, Maryland, the National Oceanic and Atmospheric Administration (NOAA), the U.S. Fish and Wildlife Service (FWS), the Maryland Department of Natural Resources (MDNR), and the Maryland Department of the Environment (MDE) are conducting a natural resource damage assessment (NRDA), which involves implementing studies to identify and quantify injured resources and services. This fact sheet provides summary information about one of the studies.

Study Objectives

The objectives of this study are to document the relative abundance and diversity of adult and juvenile fish, fish larvae, and fish eggs (ichthyoplankton), and compare post-spill abundance and diversity with areas not affected by the spill and with historic fish community information.

Methodology Overview

Field protocols were conducted generally as outlined in the Natural Resource Damage Assessment Emergency Guidance Manual (NOAA 1997). Field surveys included trawl surveys for adult and juvenile fish and ichthyoplankton tows for earlier lifestages. Trawl surveys were conducted in the Patuxent River using a standard 16-foot trawl; they took place for 6 minutes each at 5 stations between Trueman Point (4 miles upstream from Swanson Creek) and Broomes Island (11 miles downstream). All fish collected in the trawl were identified by species, counted, and measured to the nearest centimeter.

Ichthyoplankton surveys were conducted using standard protocols. These surveys used a midwater trawl with a 0.5-mm mesh plankton net mounted in the trawl. Tows took place for approximately 5 minutes against the direction of the current in the Patuxent River between Lyons Creek (approximately 12 miles upstream) to Sheridan Point (approximately 6 miles downstream). After each tow, the contents of the plankton net were collected in a sample jar and preserved in 10-percent buffered formalin until transfer to a laboratory for processing. Processing consisted of sorting fish eggs and larvae from the debris and identifying fish specimens by species. Selected species, such as striped bass, were measured to the nearest millimeter. Results will be compiled and compared to historic abundance and diversity information and to background areas outside the spill area.


Eight trawl surveys took place between April 10 and May 10. Between May and October, six monthly trawl surveys were conducted in the Patuxent River from Deep Landing downstream to Broomes Island. Analysis of trawl results and monthly monitoring results will compare post-spill results with historic and background data.

Eleven ichthyoplankton surveys took place between April 10 and May 15; a total of 68 samples were collected. These samples are currently being processed. Results will be compared with historic and background conditions.


The trawl and ichthyoplankton sampling plans were developed jointly by the NRDA Council, which consists of representatives of NOAA, FWS, MDNR, MDE, ST Services, and PEPCO. Biologists with the MDE Fish Kill Investigation Section conducted the trawl surveys during the first month of sampling. PEPCO biologists conducted monthly trawl surveys from May through October as part of their standard monitoring program. MDNR fisheries biologists conducted ichthyoplankton surveys. Ichthyoplankton samples are being processed by Environmental Consulting Services, Inc., of Middletown, Delaware.

For More Information

Contact one of the following individuals or visit a web site for more information.


Jim Hoff
Lisa Pelstring
NOAA Damage Assessment Remediation and Restoration Program
1305 East West Highway
Building 4, Room 10218
Silver Spring, MD 20910
301.713.3038 x 95
Fax 301.713.4387

This summary is meant to provide only an overview. More information on NRDA studies can be found in the Swanson Creek administrative record located at the following sites:

Light Point Commerce Center
30383 Three Notch Road
Charlotte Hall, MD
fax 301.290.0943
Monday–Friday, 9 a.m. to 5 p.m.

Calvert Industrial Park
230 Bugeye Square
Prince Frederick, MD
Fax 202.721.5028
Monday–Friday, 9 a.m. to 5 p.m.
Information Resource Center
Maryland Department of Natural Resources
580 Taylor Avenue, B–3
Annapolis, MD 21401
Fax 410.260.8951
Monday–Friday, 8 a.m. to 4 p.m.


NOAA. 1997. Natural Resource Damage Assessment Emergency Guidance Manual, version 3.1.

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