Activity space and movement patterns of Octopus bimaculatus (Verrill, 1883) around Santa Catalina Island, California

Abstract

The spatial movement and ecology of highly mobile marine predators can strongly influence, and be influenced by, a variety of ecological factors. Octopuses are voracious predators, and their predatory behavior can have significant impacts on the abundance and diversity of their prey communities. Nine Octopus bimaculatus (Verrill, 1883) were tagged and tracked during August 2014 using active tracking techniques. Octopus GPS position was recorded daily over the course of 12.9±5.6days (mean±SD) and continuous movement was tracked for 20.8±5.0h (mean±SD) for each animal. O. bimaculatus occupied an activity space of approximately 6000±3000km2 (mean±SD). Larger animals moved over larger areas, but activity space size was not correlated with octopus sex, habitat location, or time of day. Movement distances and diurnal movement patterns were highly variable for this species, both within and between individual octopuses. O. bimaculatus were highly mobile compared to other octopuses of similar size tracked in a similar way. These results are contradictory to previous estimates of movement and den fidelity for this species in this area, suggesting either a previous underestimate of O. bimaculatus movement, or a change in the way this species moves through its environment. This study pioneered the application of acoustic telemetry to octopuses in California ecosystems, and provides insight into the heterogeneity of octopus behavior and the potential impacts this heterogeneity may have on octopus prey and predator communities.