Subcutaneous electromagnetic tagging of benthic octopus: a preliminary evaluation

Abstract

Electromagnetic tags were subcutaneously implanted in the dorsal crown of 28 octopus (20 aquarium tagged; and 8 wild octopus tagged in situ) from two species: Octopus tetricus and O. maorum. Laboratory tagged octopus retained tags for the duration of the study (14 months), as did octopus tagged in the wild (13 weeks). No signs of lesions, physical deterioration, or abnormal behaviours were apparent in either laboratory or field tagged octopus. Tagging had no significant effect on growth trajectories. Both laboratory and field tagged octopus appeared healthy, physically vigorous, maintained voracious apetites, and regularly stalked and attacked vigorous prey (laboratory observations only). Subcutaneously implanted electromagnetic tags enabled individuals to be tagged, and tags to be read in situ with minimal disturbance to the animal. Electromagnetic tagging is a potentially invaluable tool in studying benthic octopus and may have similar value in the study of many cephalopods and other soft bodied organisms.