Patterns of movement and habitat use by leafy seadragons tracked ultrasonically

Abstract

Nine adult leafy seadragons Phycodurus eques were tracked using ultrasonic telemetry for between 2-10 days around West Island, Australia. All fish except one moved within well-defined home ranges of up to 5 ha (using minimum convex polygon method). Short bursts of movement (at average velocities of 2-17 m h1) punctuated long periods (up to 68 h) without movement. The exceptional fish moved almost in a straight line away from its tagging location near the end of the tracking period, at a maximum velocity of 146 m h1. There was no constant diel pattern in movements; some fish moved more at night, others during the day. The time leafy seadragons spent over particular habitats compared to the area of those habitats available at the study site was greater for Posidonia seagrass, about as expected for kelp-covered reefs and bare sand patches, and less than expected for Amphibolis seagrass and boulders covered with brown algae. In searching for tagging effects, a comparison of movement immediately after tagging showed no difference with subsequent movements for most fish. The lack of tagging effect may be because the transmitter can be attached to the bony appendages away from the body of the fish. There was no sign of damage to fish upon removal of transmitters after tracking.