Who would have expected that Port-Jackson sharks can travel long distance when seeing these little guys resting in the bottom of New South Wales in Sydney Harbour or Jervis Bay during winter months?
The BEEF lab from Macquarie University led by Prof Culum Brown has been studying these little mysterious creatures, endemic of Aussie waters, for years now and have investigated their long-term movement patterns using acoustic telemetry. Every winter the team went to Jervis Bay where PJs are forming large aggregations and caught sharks to implant them an acoustic transmitter. When the tagged shark passes in proximity of a receiver its identity is recorded allowing to follow them in time and space. The movements of these littles guys can then be tracked along a huge Australian network of receivers.
I was fortunate to participate in this project by analysing the data during my post doc at Culum’s lab last year. And the results are available in a Special Issue of Marine and Freshwater Research.
What the team found was surprising and exciting!!!!
These small benthic sharks not only come to NSW every winter but they were tracked as far as Tasmania, swimming >1,000 km after leaving their mating aggregation in Jervis Bay!
Moreover, they not only conducted long distances but they also came back every single year to exactly the same reef in Jervis Bay after their > 2,000 km travel (round-trip), becoming an astonishing migrating species with strong site fidelity and philopatry!
In summary, they forage in southern Australia and move to NSW to reproduce in winter, with males arriving earlier than females at the mating aggregation sites.
All this little sharks are aggregating in great numbers and are socialising for mating. We are now tracking their interactions and investigating their social network. How? Wait for a few more days as we have a paper accepted for publication on this!
The paper can be found at:
Bass N, Mourier J, Day J, Knott N, Guttridge T, Brown C (2017) Long-term migration patterns and bisexual philopatry in a benthic shark species. Marine and Freshwater Research 68(8): 1414-1421.