Diet Patterns of American Eel, Anguilla rostrata, in the James River Drainage, Virginia

ABSTRACT

We examined variation in the diet of inland American eels (Anquilla rostrata) over gradients of eel size, stream size, and physiography. Stomach contents of 367 eels from 21 streams from the James River drainage, Virginia were analyzed. Electrofished eels were grouped into three categories of total length (TL) (100—249 mm TL, 250—374 mm TL, > 374 mm TL), stream size (orders 3—4, 5—6, 7—8), and physiographic region (coastal plain, lower piedmont, upper piedmont). Overall, prey size increased with eel size. Aquatic insects were the major prey of small eels, whereas fish and crayfish were the major prey of large eels. The diet of medium size eels was intermediate between small and large sizes; aquatic insects predominated numerically and fish predominated by weight. Diet did not vary significantly with respect to stream size in the upper piedmont, the only region where we examined a stream size gradient. In both piedmont regions, aquatic insects were the most common prey of small and medium eels, whereas large eels consumed mostly fish and crayfish. In the coastal plain, microcrustaceans and aquatic insects were the major prey of small and medium eels, whereas large eels ate mostly crayfish. Consumption of fish was largely restricted to large eels from the upper piedmont and was not observed for any coastal plain eels.