Foraging patterns of juvenile western rock lobsters Panulirus cygnus George

Abstract

Foraging patterns of juvenile western rock lobster Panulirus cygnus George were investigated in the field by tracking lobsters with electromagnetic tags for up to 3 wk. Most foraging activity begins in response to changes in light levels associated with dusk and not by diurnal changes in water temperature or currents. Similarly, lobsters return from foraging around dawn when light levels start to increase. Foraging activity was constant throughout the night, and males were more active than females. Lobsters usually moved at a rate of ≈ l m · min −1 at night, although sometimes they travelled up to 18m· min −1 when walking over bare sand. They often lived on one reef but travelled to forage on seagrass beds in front of another reef, sometimes visiting a den on that reef. Some lobsters used several dens on different reefs during the 3 wk of observation. Although lobsters foraged in both of the two main structural varieties of seagrass beds, Amphibolis and Heterozostera with Halophila, they foraged for longer periods in the Heterozostera with Halophila beds. Foraging ranges varied within and between individuals although an individual lobster might forage in the same general area on a few successive nights or even up to several weeks.