Researchers have made significant strides in understanding humpback whale migration patterns along the east coast of Australia through the installation of hydrophones off the New South Wales (NSW) South Coast. Tammy and Michael Bellette, passionate marine guardians from our south coast, deployed the two hydrophones in deep water, with one located close to Batemans Bay. This work is made possible through the Whales and Climate Research Program. Through its use, it hopes to track, study and better understand the habits of these magnificent animals.
Tropical wallabies were a hit with Jakob even while scuba diver Michael Bellette celebrated anchoring the hydrophone in 28 metres of water. The device recorded whale calls and songs non-stop for more than six months, using passive acoustic monitoring to record audio data around the clock. Researchers aimed to make the most of the long recording period. They collected an incredible amount of information on the occurrence and activity of humpback whales throughout the region.
Data Collection and Analysis
After over six months of deployment, the hydrophone was recovered from the ocean floor just south of Batemans Bay. Milly Street, a student at Griffith University, dedicated the past year to analyzing an astounding 11,000 audio files recorded by the hydrophone. Her work informs a more general understanding of how and why migration patterns are changing as people around the world react to environmental changes.
Street’s results show that researchers consistently saw ‘CI skipper’ whales around the south coast. These were reported from April through the end of November, corroborating visual observations. Street commented that her research might change the fate of humpback whales. They could be reaching their important habitats—such as breeding and feeding grounds—sooner or later than they used to.
Bioacoustic recordings from the hydrophone revealed that some female humpback whales are foregoing their entire migration north. Rather, they prefer to remain in sheltered shallower waters when not spawning. We learned that some female humpback whales skip the long migration north when they’re not breeding. Rather, they just want to hang out in the protected calm lower waters, Street replacement.
Implications for Whale Conservation
The result of this analysis of whale sounds has important implications for understanding and protecting these majestic marine mammals. Barry McGovern, a marine biologist, noted that the more whales come back, the harder it is to predict their migration patterns. In the past when there were more whales, there were much more distinct beginning and end markers to the migration. But now, due to the abundance of these same whales, you can get sounds all the time,” he told us.
Street emphasized the importance of using acoustic data to inform conservation efforts: “It’s important that we use this data to understand their migration timing along our east coast to protect them from any potential threats, and to understand when and where they’re in specific areas as well.”
Future Directions
Luckily, this project will be part of a larger, multi-agency effort to study the migration patterns of humpback whales. Our researchers are trying to figure out what’s behind these patterns on Australia’s east coast. This long-term research is designed to continually refine conservation efforts with evidence gained from the evolving science that comes from acoustic monitoring.
Street said we would typically expect a modest reduction in the acoustic presence of humpback whales. This transformation will be happening on the south coast of NSW. The preliminary results indicate a healthy population, with many peaks of acoustical activity observed for the entire period the hydrophone was deployed.
