Pit stop off the humpback highway: multi agency response to a sub-adult humpback whale Megaptera novaeangliae in Sydney Harbour, Australia

The east coast Australian humpback whale Megaptera novaeangliae population continues to recover post-whaling and is now estimated to be at least 50,000 individuals. The combination of population growth and increased human activities within coastal environments means there is a high likelihood of human interactions with whales. On 16 July 2025, a single sub-adult humpback whale swam up to 7 km into Sydney Harbour, Australia, passing within close proximity to many vessels and other human-made structures. The whale swam into Circular Quay, the busiest central ferry terminal in the harbour, halting peak-time morning vessels with all boat traffic having to shut down as a safety measure. While in the Quay the whale was escorted by authorities to minimise the risk of vessel strike. Over the course of a single day, the whale was documented at 47 separate locations within the harbour by authorities and citizen scientists, through social media posts and reports to local marine organizations. The whale was last seen in the harbour at 17:50 hours that evening, and not sighted inside the harbour again. This short note documents a successful multi-agency response to manage the safety of vessels and of a large and protected marine mammal, and provides a framework for managing similar future occurrences.