Science Serving Maryland's Coasts
Michael Wilberg, Ph.D.
Chesapeake Biological Laboratory
Variability in Abundance of the American Eel (Anguilla rostrata) in the Potomac River
American eel (Anguilla rostrata) harvests along the Atlantic coast of the U.S. have been declining since the late 1970s. It is thought that abundance may be declining to critically low levels. The objective of this study was to evaluate intra and inter-annual trends in catch-per-unit-effort (CPUE) and potential causes of trends. Catch and effort data were used to calculate CPUE as an index of abundance in order to evaluate whether American eels declined in the Potomac River during 1996-2007. Additionally, water quality parameters such as salinity, dissolved oxygen, and water temperature were examined to determine if they explained any of the variation in CPUE. Results showed an increase in CPUE for half of the years studied, indicating that the stock status is not in as dire a situation as implied by a study in the Potomac River during 2007. The overall yearly CPUE from 1996-2007 showed an increasing trend. There seemed to be a slight effect of salinity on CPUE, but dissolved oxygen and water temperature appeared to have little effect.
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