Ultrasonic Telemetry of American Eel Movements in a Tidal Creek

Abstract

Movements and distribution of eight immature American eels Anguilla rostrata were monitored periodically with location-only ultrasonic transmitters for 5 days in Fridaycap Creek, a Georgia estuarine stream. Fish were concentrated within 25 m of the mouths of feeder creeks. Movements were usually with tidal currents and were restricted to 400 m of the 1,000-m study section. Moves greater than 50 m usually involved round trips from and to a point of origin. Limited movements and regions of concentrated activity may be evidence of home ranges within the creek. Daytime movements were restricted to the main creek channel, shorelines being preferred during high tides and the midchannel during low tides. At night, fish were generally near mouths of feeder creeks during low tides; they often moved up feeder creeks and even onto the marsh with a flood tide, returning to the feeder mouth as the tide ebbed. Tendency to move with tidal currents, activity region sizes, and types of habitats frequented were all more variable at night. Our results suggest a basic pattern of nocturnal activity and diurnal inactivity that is modified by tidal flow.