CONNECTIVITY STUDIES

Movements of Top Predators

SPOT tag attached to dorsal fin of tiger shark (Jill Zamzow).

Top predators play an important role in ecosystems by shaping communities in the Monument, this role is filled by sharks. Science-based management of the fish resources in the Hawaiian Archipelago requires that we know whether key species are site attached to specific areas and, if not, how frequently and extensively they move. Different management options may be available if the populations of key species are “tied” to individual atolls, rather than if significant numbers of individuals move between atolls or, throughout the Hawaiian Archipelago. This work uses acoustic and satellite telemetry to look at top predators movements between open-ocean and atolls, and to determine habitat use.

A tiger shark is equipped with a transmitter (Luiz Rocha).

There are now a total of 90 receivers that have recorded 514,397 detections of 104 top predators equipped with acoustic transmitters in Monument waters. Results indicate that tiger sharks Galecerdo cuvier are the most wide-ranging top predator in the Monument, and there have been no inter-island movements by ulua or uku (C. ignobilis & Aprion virescens) Both ulua (C. ignobilis) and uku (A. virescens) exhibited well-defined patterns of movement with distinct diel, seasonal & lunar components. In addition we found that individual ulua at FFS return to the same spawning sites in successive years.

For more information visit: http://www.hawaii.edu/HIMB/sharklab/

[ Top of the page ]