Population dynamics, Anguillicola crassus infection, and feeding selectivity of American eel (Anguilla rostrata ) in tributaries of the Hudson River, New York

This research examined the population dynamics of American eel ( Anguilla rostrata) in tributaries of the Hudson River, New York. Eel density ranged from 0.0 to 155.1 eels/100m2. Increased barrier intensity reduced eel density by at least a factor of 10 and significantly reduced eel condition; however, eel growth was higher above barriers. Although the invasion of Anguillicola crassus is ongoing, prevalence (39%) and intensity (2.4 nematodes/eel) were increased in highly urbanized sites, and were significantly lower upstream of barriers (p < 0.01). Parasite prevalence (39%) and intensity (2.4 nematodes/eel) were increased in highly urbanized sites, but were significantly lower upstream of barriers (p < 0.01). A. crassus invasion is ongoing. Infection with the Anguillicola crassus did not alter prey preferences or yellow-phase eel condition. As eels grew, feeding selectivity changed from smaller softer-bodied prey (e.g. Chironomidae, Baetidae) to larger harder-bodied prey items (e.g. Cambaridae).