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3 weeks ago
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A new way of keeping tabs on hard-to-track marine species such as orcas has been developed by researchers in the USA – and it puts to good use underwater telecoms cabling that once redundant lies dormant on the seabed.
Two kilometres of fibre-optic cable were specially laid near the San Juan Islands in Puget Sound off Washington state on 10 October to demonstrate the potential of using such installations to monitor endangered marine animals.
Connecting cable from the boat to shore (University of Washington Bothell)The University of Washington Bothell reckons its research project could revolutionise marine conservation. It is based on a technology called Distributed Acoustic Sensing (DAS), originally developed to detect seismic activity but, since proving capable of tracing the presence of marine mammals, now making detailed real-time monitoring of vast ocean areas a possibility.
Ready to use
Thousands of kilometres of underwater cabling around the world lies ready to be used for the purpose, according to Dr Shima Abadi, a professor at Washington Bothell’s School of STEM and at its School of Oceanography.
She and her research team have spent two years monitoring southern resident orcas using tens of kilometres of pre-existing cable near Whidbey Island and Seattle. Where hydrophones, previously used for such research, detect sounds at a single point, DAS transforms fibre-optic cables into receiver arrays that can pick up sounds along their full length.
Anchoring the fibre-optic cable spools from the boat to the bottom of Puget Sound (University of Washington Bothell)
Divers position and check the cable after installation (University of Washington Bothell)The cables are connected to an “interrogator” that sends laser pulses through them and measures when they are affected by vibrations or acoustic energy. The researchers say they can then pinpoint and analyse the precise location and nature of the disturbance.
Earlier warnings
There has been concern that rising sea temperatures, food scarcity and maritime traffic could be disrupting the traditional migration patterns of orcas in the region. Because they spend most of their time beneath the surface, often in poor visibility, sound is the best tool for observing these patterns.
Southern resident orca in Puget Sound (Erik Stockdale)“We hope to show that fibre-optic cables can detect southern resident orca vocalisations, enabling us to triangulate the orcas’ locations and better track them – allowing earlier warnings to vessels to reduce speed or avoid the area,” says Abadi.
“This innovative approach could be a breakthrough in conservation efforts and open new possibilities to expand analysis on a much larger temporal and spatial scale.”
The team, with Abadi third from left (University of Washington Bothell)The DAS project is supported by a $1.5 million grant from Allen Family Philanthropies, and its science director Dr Yuta Masuda says he hopes it will lead to a global monitoring network being created to protect endangered species.
“This research could drastically increase our understanding of marine mammals and complement other technologies being deployed for monitoring human impacts on marine life,” he says.
Over the next two years, Abadi’s team will track data and work alongside local charities such as Beam Reach, which can provide comparative data from its more-traditional hydrophone network.
