Abstract
We examined population traits of yellow American eels from nine sites with similar habitat characteristics in each of four rivers in Maine, U.S.A. Migrating silver eels were also collected to compare sex ratio, age and size at migration among the four rivers. Population density and biomass were not significantly different among rivers with mean ranges of 8.4–21.8 eels 100 m−2and 380–1485 g m−2. Pairwise comparisons of the slopes of weight–length relationships of log transformed data (pooled data: intercept = −6.007, slope = 3.094, r2= 0.99, and n = 3116) revealed no significant differences among rivers. Length–age relationships (pooled data: intercept = 87.826, slope = 23.444, r2= 0.76, and n = 2325) also showed no statistically significant pairwise differences in slopes among rivers. In all rivers, sexual differentiation was complete by 270 mm total length and age eleven. The sex ratios of migrating silver eels were not correlated with yellow eel sex ratios among the four rivers. Mean age at migration among the four rivers was significantly different for males only, with a range of 1.3 years. Both sexes had some significant differences in size at migration among rivers, but the biological importance of the differences is tenuous (male range: 15 mm, female range: 36 mm). The yellow and silver eel population traits from these four rivers showed little variation when riverine habitat was isolated. Variations in traits appeared to be greater when eels from non-riverine habitats may have been present.
Similar content being viewed by others
References cited
Avise, J.C., G.S. Helfman, N.C. Saunders & L.S. Hales. 1986. Mitochondrial DNA differentiation in North Atlantic eels: population genetic consequences of an unusual life history pattern. Proc. Nat. Acad. Sci. U.S.A. 83: 4350-4354.
Beullens, K., E.H. Eding, P. Gilson, F. Ollevier, J. Komen & C.J.J. Richter. 1997. Gonadal differentiation, intersexuality and sex ratios of European eel (Anguilla anguillaL.) maintained in captivity. Aquaculture 153: 135-150.
Bouillon, D.R. & R.L. Haedrich. 1985. Growth of silver eels (Anguilla rostrata) in two areas of Newfoundland. J. Northw. Atl. Fish. Sci. 6: 95-100.
Colombo, G. & G. Grandi. 1996. Histological study of the development and sex differentiation of the gonad in the European eel. J. Fish Biol. 48: 493-512.
Frost, W.E. 1945. The age and growth of eels (Anguilla anguilla) from the Windmere catchment area: part 1. J. Anim. Ecol. 14: 26-36.
Gray, R.W. & C.W. Andrews. 1970. Sex ratio of the American eel (Anguilla rostrata(LeSueur)) in Newfoundland waters. Can. J. Zool. 48: 483-487.
Gray, R.W. & C.W. Andrews. 1971. Age and growth of the American eel (Anguilla rostrata(LeSueur)) in Newfoundland waters. Can. J. Zool. 49: 121-128.
Guerrero, R.D. & W.L. Shelton. 1974. An aceto-carmine squash method for sexing juvenile fishes. Prog. Fish-Culturist 36: 56.
Hansen, R.A. & A.G. Eversole. 1984. Age, growth, and sex ratio of American eels in brackish-water portions of a South Carolina river. Trans. Amer. Fish. Soc. 113: 744-749.
Helfman, G.S., E.L. Bozeman & E.B. Brothers. 1984. Size, age, and sex of American eels in a Georgia river. Trans. Amer. Fish. Soc. 113: 132-141.
Helfman, G.S., D.E. Facey, L.S. Hales, Jr. & E.L. Bozeman, Jr. 1987. Reproductive ecology of the American eel. Amer. Fish. Soc. Symp. 1: 9-13.
Jessop, B.M. 1987. Migrating American eels in Nova Scotia. Trans. Amer. Fish. Soc. 116: 161-170.
Kleckner, R.C. 1980. Swimbladder wall guanine enhancement related to migratory depth in silver phase Anguilla rostrata. Comp. Biochem. Physiol. A 65: 351-354.
Krueger, W.H. & K. Oliveira. 1997. Sex, size, and gonad morphology of silver American eels Anguilla rostrata. Copeia 1997: 415-420.
Krueger, W.H. & K. Oliveira. 1999. Evidence for environmental sex determination in the American eel, Anguilla rostrata. Env. Biol. Fish. 55: 381-389.
Levesque, J.R. & W.R. Whitworth. 1987. Age class distribution and size of American eel (Anguilla rostrata) in the Shetucket/Thames River, Connecticut. J. Freshw. Ecol. 4: 17-22.
Michener, W.K. & A.G. Eversole. 1983. Age, growth, and sex ratio of American eels in Charleston Harbor, South Carolina. Proc. Annu. Conf. Southeast Assoc. Fish & Wildlife Agencies 37: 422-431.
Naismith, I.A. & B. Knights. 1993. The distribution, density and growth of the European eel, Anguilla anguilla, in the freshwater catchment of the River Thames. J. Fish Biol. 42: 217-226.
Oliveira, K. 1996. Field validation of annular growth rings in the American eel, Anguilla rostrata, using tetracycline-marked otoliths. U.S. Fish. Bull. 94: 186-189.
Oliveira, K. 1997. Movements and growth rates of yellow-phase American eels in the Annaquatucket River, Rhode Island. Trans. Amer. Fish. Soc. 126: 638-646.
Oliveira, K. 1999. Life history characteristics and strategies of the American eel, Anguilla rostrata. Can. J. Fish. Aquat. Sci. 56: 795-802.
Rossi, R. & G. Colombo. 1979. Some observations on age, sex, and growth of silver eels (Anguilla anguillaL.) in north Adriatic lagoons. J. Cons. Int. Explor. Mer 174: 64-69.
Smogor, R.A., P.L. Angermeier & C.K. Gaylord. 1995. Distribution and abundance of American eels in Virginia streams: tests of null models across spatial scales. Trans. Amer. Fish. Soc. 124: 789-803.
Sokal, R.R. & F.J. Rohlf. 1995. Biometry. The principles and practice of statistics in biological research, 3rd ed. Freeman, New York. 887 pp.
Vøllestad, L.A. 1992. Geographic variation in age and length at metamorphosis of maturing European eel: environmental effects and phenotypic plasticity. J. Anim. Ecol. 61: 41-48.
Vøllestad, L.A. & B. Jonsson. 1986. Life-history characteristics of the European eel Anguilla anguillain the Imsa River, Norway. Trans. Amer. Fish. Soc. 115: 864-871.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Oliveira, K., McCleave, J.D. Variation in Population and Life History Traits of the American Eel, Anguilla rostrata, in Four Rivers in Maine. Environmental Biology of Fishes 59, 141–151 (2000). https://doi.org/10.1023/A:1007631108201
Issue Date:
DOI: https://doi.org/10.1023/A:1007631108201