Oral Presentation Australian Society for Fish Biology Conference 2017

Navigation and homing ability in a benthic shark (#117)

Sherrie L Chambers 1 , Culum Brown 1 , Catarina Vila Pouca , Nathan Knott
  1. Macquarie University, Sydney, NSW

Many elasmobranchs undertake large-scale migrations to specific locations for events such as mating, pupping or feeding, and return regularly to these places throughout their lives. The Port Jackson shark is a small, benthic species that uses rocky reef habitat in NSW over winter for breeding and egg laying, and exhibits extremely high site fidelity between years. This study investigates homing ability and magnetic navigation in the Port Jackson shark by displacing animals from their ‘home reef’ and examining their movements. Sharks (n = 20) were captured in southern Jervis Bay, acoustically tagged, and translocated ~8kms north, half with strong magnets attached to their heads and half with a sham attachment. The time taken to return ‘home’ ranged from 3 hours to 13 days, with 3 sharks never detected back in the home reef. Whilst there was no significant difference between magnet and control groups, differences were observed based on sex; males returned more quickly than females. These results indicate that Port Jackson sharks have a well-developed homing ability but do not use a magnetic sense to navigate over short distances. This study raises further questions about how the sharks use space and other resources during breeding season, and provides important information on the spatial ecology of benthic sharks.