Developed by Oregon State University researchers in partnership with Telonics, Inc., the tag will allow researchers to observe key whale behaviour events, identify important habitat and better understand whales’ response to human activity such as ship traffic or military sonar.
Rising shipping traffic puts whales at an increased risk of being struck by large vessels. The upper 30m of the water column – the vertical expanse from the water’s surface to the ocean floor – is considered the ‘danger zone’ for whales passing through shipping lanes.
“One of the benefits of these new tags is that they give us information about how much time whales are spending within the danger zone throughout their migration,” said Daniel Palacios, endowed associate professor in whale habitats at OSU’s Marine Mammal Institute. “With that information, we can identify areas of higher risk and make more informed decisions to help protect them from the threat of ship strikes.”
The ability to monitor dive behaviour and detect changes could also have applications for measuring how whales respond to sources of loud sound, such as sonar used by the US Navy, he added.
The so-called RDW tag could have further applications for new areas of research, including marine mammal physiology, behaviour, ecology and conservation. The features and benefits of the new tag are described in a paper published in Animal Biotelemetry.
“Whales spend the vast majority of their lives underwater, where we can’t see them,” said paper co-author Ladd Irvine, a senior faculty research assistant with the Marine Mammal Institute, part of OSU’s College of Agricultural Sciences. “They can move more than 100km in a day, so typical methods of observation aren’t reliable for keeping track of where they are going or what they are doing. Tags allow us to ride along with the whales as they go about their lives.”
Previously, technological limitations have prevented long-term tracking of whale feeding behaviour. When lunge-feeding, a whale will dive deeply and consume a large quantity of prey and water, then filter out the water. Previous satellite tracking devices could monitor their horizontal movements, but not their behaviour while diving.
Working with Telonics, Inc., Oregon State researchers developed the new RDW tag to incorporate pressure and accelerometer sensors that will allow them to monitor more of the whales’ movements, including lunge-feeding, via satellite for multiple months.
Software in the tag creates a behaviour summary for every dive and transmits the data via satellite. The software also adapts over time to better detect key events in the accelerometer data.
“This new system allows us to monitor the feeding behaviour of baleen whales over much longer periods of time than was previously possible with other types of tags,” Irvine said in a statement. “In the past we’ve been able to monitor the long-term movements of whales, but this additional information helps us better understand what they are doing in those places in 3D.”
The new tags, which are implanted in the whales’ blubber, were tested on 14 blue and 14 humpback whales off the coast of Southern California. Data collected from the tests was similar to what a simulation produced, confirming their effectiveness.
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