Thousands of Port Jackson sharks were recently observed in a large aggregation on the seabed of Beagle Marine Park, a protected area in the Bass Strait between mainland Australia and Tasmania. This unique gathering, discovered by researchers from the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS), consisted entirely of female sharks, raising intriguing questions about their behavior.
Port Jackson sharks, scientifically known as Heterodontus portusjacksoni, are a common species in Australia’s southern waters. Easily identifiable by the two prominent ridges extending from their noses to the backs of their heads, these nocturnal sharks can reach lengths of up to 5.5 feet (1.6 meters). They primarily feed on squid, octopuses, and crustaceans. Unlike some shark species, Port Jackson sharks are not considered threatened or endangered.
The Discovery of the Shark Gathering
The IMAS research team, led by senior research fellow Dr. Jacquomo Monk, made the discovery while using a remotely operated underwater vehicle (ROV) to survey the seabed. At a depth of approximately 213 feet (65 meters), the ROV encountered a dense aggregation of sharks, described as being “tightly packed like a carpet spread across the seafloor.”
This wasn’t the first encounter with such a gathering for the IMAS team. Six years prior, during a previous expedition, they observed a similar aggregation in the same marine park. This return visit aimed to assess changes in the park’s conditions over time. Finding the sharks again in the vast 3,000 square kilometer (1,158 square mile) park highlighted the significance of the area for these animals, according to Dr. Monk.
An All-Female Enigma
What surprised the researchers this time was the exclusively female composition of the group. This observation has sparked further inquiries, particularly as male and female Port Jackson sharks typically live separately outside of mating season. The reasons behind this all-female gathering remain a mystery. Dr. Monk suggested that they might be taking advantage of a local food source, such as doughboy scallops, before migrating north for egg-laying.
Harmless to Humans
While the image of a large shark gathering might evoke the recent Netflix film Under Paris, Port Jackson sharks pose no threat to humans. Even in the extremely rare instances of bites, the result is usually limited to a bruise and a torn wetsuit.
The Importance of Beagle Marine Park
The repeated observation of these shark aggregations underscores the importance of Beagle Marine Park as a crucial habitat for Port Jackson sharks. Further research will hopefully shed light on the reasons behind these gatherings and contribute to the ongoing conservation efforts for this fascinating species.
In conclusion, the discovery of this all-female Port Jackson shark gathering presents a captivating puzzle for marine researchers. While the specific reasons for their aggregation remain unknown, the observation highlights the ecological significance of Beagle Marine Park and the need for continued research to understand the behavior and conservation needs of this unique shark species.
