Thousands of sleepy Port Jackson sharks have been spotted by scientists revisiting Beagle Marine Park in central Bass Strait for the first time in six years.
The discovery was made during a two-week survey led by the University of Tasmania Institute for Marine and Antarctic Studies (IMAS), aiming to monitor changes in the park’s condition since its establishment in 2017.
Dr Jacquomo Monk, the voyage leader, said that finding the sharks again was like finding a needle in a haystack.
“It was very exciting when we managed to traverse over a rise in the reef to get a glimpse of the sharks snoozing 65-metres below the vessel in almost the same location as they were six years ago,” Dr Monk said.
“There were thousands of sharks tightly packed like a carpet spread across the seafloor.”
Port Jackson sharks grow to around 1.6 metres in length and are found across southern Australia.
They rest on the ocean floor by day and emerge at night to hunt for food like squids, octopuses and crustaceans.
“One of the interesting things we discovered this time is that the Beagle gathering appears to be only for females,” Dr Monk said.
“This poses more questions than answers for us, but we know that the males and females of this species often live apart, except when mating.
“We don’t know exactly why the females are here. Perhaps they are feasting on the local delicacy doughboy scallops before the long trip north to lay their eggs.”
The scientists hope to learn more about the reasons behind the gathering through ongoing research.
Beagle Marine Park is one of 60 Australian Marine Parks managed by Parks Australia, protecting diverse sponge gardens and serving as an important foraging area for seabirds breeding on nearby islands.
The survey took thousands of underwater images and videos to create an inventory of marine life in different depths and habitats in the park.
These images will help park managers assess how well the area is meeting conservation goals.
The research vessel is scheduled to return to Beauty Point in Tasmania on August 18th.
