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Eel Ecology

The American eel life cycle can be separated into two broad phases: 1) An oceanic phase in which silver eels migrate to the Sargasso Sea, spawn and die; eggs and leptocephali (larvae) drift; and glass eels disperse into near-shore habitats of North America. Very little is known about this phase, and what is known is largely outside of the influence of management. 2) An estuarine / freshwater phase in which glass eels and elvers disperse throughout watersheds, and grow into a sedentary yellow eel stage. For this phase there is probably sufficient attainable knowledge to recommend action to maintain populations within limits imposed by recruitment and local productivity. Our research is aimed at determining basic demographic information in support of better fisheries management of eel stocks. The Chesapeake Bay is a center for American eel yields, most of which are exported abroad.

Elvers and yellow eels are sedentary, showing strong affinity to local regions (100 - 10,000 m) in nearshore coastal environments, estuaries, and non-tidal fluvial and lacustrine habitats. Precise site affinity ("homing") within these stages has been demonstrated through telemetry, tagging and mechanistic studies. These stages show high rates of phenotypic plasticity in growth, sex differentiation, maturation size and age, diet, morphology, and habitat shifts. Many of these life history attributes are associated with habitats that are colonised by elvers / yellow eels. Analyses of otolith microchemistry indicate that yellow eels show different modes of habitat use: stage-long residency in freshwater, estuarine or coastal waters, and habitat shifts from freshwater to brackish water. These modes of habitat use have consequences to growth and maturation rates.

Section of otolith from Hudson River eel estimated to be 27 years old

Final Report to the Hudson River Foundation: Ecology and Contamination of the Hudson River American Eel [2.4 Mb; will open in a new window]


Fenske, K.H., M.J. Wilberg, D.H. Secor, and M.C. Fabrizio. 2011. Age-structured production model for American eels (Anguilla rostrata) in the Potomac River, Maryland. Can. J. Fish. Aquat. Sci. 68: 1024-1037.

Fenske, K.H., D.H. Secor, and M.J. Wilberg. 2010. Demographics and parasitism of American eels in the Chesapeake Bay. Trans. Am. Fish. Soc. 139: 1699-1710.

Cairns, D.K., D.H. Secor, W.E. Morrison, and J.A. Hallet. 2009. Salinity-linked growth in anguillid eels and the paradox of temperate-zone anadromy.  J. Fish Biol. 74: 2094–2114

Arslan, Z. and Secor, D.H. 2005. Analysis of trace transition elements and heavy metals in fish otoliths as tracers of habitat use by American eels in the Hudson River estuary. Estuaries. 28: 382-393.

Morrison, W.E. and D.H. Secor.  2003. Demographic attributes of yellow-phase American eels in the Hudson River Estuary.  Can. J. Fish. Aquat. Sci. 60: 1487-1501

Morrison, W.E. and D.H. Secor.  2004. Abundance  of yellow-phase American eels in the Hudson River Estuary. Trans. Am. Fish. Soc. 133: 896-910.

Morrison, W. E., D. H. Secor, and P. M. Piccoli. 2003. Estuarine habitat use by Hudson River American eels. Am. Fisheries Society Sympos. 33: 87-99.

Kraus, R.T., and D.H. Secor.  2003.  Otolith Sr:Ca response to a manipulated environment in     young American eels.  Am. Fish. Soc. Symp. 33: 79-85.  

Barse, A. and D.H. Secor. 1999. An exotic nematode parasite of the American eel. Fisheries 24(2): 6-10.