Size, Age, and Sex of American Eels in a Georgia River

Abstract

Seasonal collections of American eels Anguilla rostrata were made with baited traps at an estuarine and a freshwater site in the Altamaha River, Georgia. Estuarine animals were on average shorter, lighter, and younger than freshwater animals, although growth was faster in the estuary. Both sites were characterized by greater weight gains in spring through fall and lesser weight gains during late winter. Males constituted 36% of sexually differentiated American eels in the estuarine population but only 6% in the freshwater population. Estuarine males grew more slowly than estuarine females. Males and females differentiated sexually at the same lengths and ages, but matured at younger ages in the estuary. Sexually undifferentiated and differentiated fish overlapped considerably in length, weight, and age at both sites. Glass eels were captured in late winter; they were 49–56 mm long and 250–300 days old. Maturing silver eels were caught during late winter-early spring and were 353–587 mm long and 3–6 years old. In general, American eels from the Altamaha River are smaller, younger, and may mature more rapidly than animals at more northern latitudes. Received February 28, 1983 Accepted December 3, 1983