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Dam removal increases American eel abundance in distant headwater streams

Transactions of the American Fisheries Society

By:
, , and
DOI: 10.1080/00028487.2012.675918

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Abstract

American eel Anguilla rostrata abundances have undergone significant declines over the last 50 years, and migration barriers have been recognized as a contributing cause. We evaluated eel abundances in headwater streams of Shenandoah National Park, Virginia, to compare sites before and after the removal of a large downstream dam in 2004 (Embrey Dam, Rappahannock River). Eel abundances in headwater streams increased significantly after the removal of Embrey Dam. Observed eel abundances after dam removal exceeded predictions derived from autoregressive models parameterized with data prior to dam removal. Mann–Kendall analyses also revealed consistent increases in eel abundances from 2004 to 2010 but inconsistent temporal trends before dam removal. Increasing eel numbers could not be attributed to changes in local physical habitat (i.e., mean stream depth or substrate size) or regional population dynamics (i.e., abundances in Maryland streams or Virginia estuaries). Dam removal was associated with decreasing minimum eel lengths in headwater streams, suggesting that the dam previously impeded migration of many small-bodied individuals (<300 mm TL). We hypothesize that restoring connectivity to headwater streams could increase eel population growth rates by increasing female eel numbers and fecundity. This study demonstrated that dams may influence eel abundances in headwater streams up to 150 river kilometers distant, and that dam removal may provide benefits for eel management and conservation at the landscape scale.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Dam removal increases American eel abundance in distant headwater streams
Series title:
Transactions of the American Fisheries Society
DOI:
10.1080/00028487.2012.675918
Volume
141
Issue:
5
Year Published:
2012
Language:
English
Publisher:
Taylor & Francis
Publisher location:
Philadelphia, PA
Contributing office(s):
Leetown Science Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Transactions of the American Fisheries Society
First page:
1171
Last page:
1179
Country:
United States
State:
Virginia
Other Geospatial:
Shenandoah National Park