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Source: University of Canterbury

23 June 2020

A new international study led by a University of Canterbury scientist has discovered paikea humpback whales stick to old migration routes despite ocean changes associated with climate change.

A new international study led by a University of Canterbury scientist has discovered paikea humpback whales stick to old migration routes despite ocean changes associated with climate change.

Understanding how organisms respond to environmental change is one of the most pressing grand challenges of organismal biology, according to the scientists. In the vast oceans that cover 71% of Earth’s surface, remote sensing technologies have created unprecedented opportunities to create new knowledge and deliver integrated understandings of marine organism-environment interactions via long-term monitoring.

Led by UC environmental scientist Associate Professor Travis Horton, a team of scientists from the United States, New Zealand and Brazil has been tracking whales using both historic Russian whaling logs and satellite tracking.

“One of the things that we’re looking at right now is solving this 3000-year-old mystery of how animals navigate. Our research on humpback whales is shedding some important light on that ancient riddle, so that’s an important outcome,” Associate Professor Horton says.

“Our unique research uses more than 15 years of satellite-monitored data, including paikea humpback whale telemetry, essential oceanographic variables and magnetic field conditions, to demonstrate that humpback whales can find and follow restricted open-ocean migration routes despite changing Earth system conditions.

“We can now predict when and where whales will be located. So the patterns that we see, the reproducibility over decades of data collection, that gives us a predictive model. We can more or less say, with reasonable probability, these humpback whales will be in this part of the ocean at this time of the year. That’s incredibly useful for conservation and identifying areas to protect.  It’s also useful for sustainable ocean science.”

Using historic whaling records and satellite-derived data, the researchers show that movement parameters associated with long-distance humpback whale migrations, including use of a south-southeast directed migratory corridor, migration path straightness, direction, timing and velocity, have not significantly changed during a period of dynamic oceanographic and geomagnetic conditions.

“These findings reveal an apparent paradox: humpback whale migrations do not change in a changing ocean,” Associate Professor Horton says.

“With respect to climate change, if the whales continue to keep going to the same places but those places change due to environmental or climate change, those habitats, those places that the whales are migrating to, may not be able to serve the whales’ needs anymore. The potential here is that the climate change, combined with the fidelity that the whales show to these particular corridors, might actually hurt the whale populations. They might go to places that don’t work anymore.”

Geophysical analyses of the same humpback whale movements demonstrate that these whales maintained prolonged migratory fidelity to a limited suite of spatiotemporal trajectories through gravitational coordinates, raising the possibility that migratory decisions are relatively insensitive to changing oceanographic and geomagnetic conditions, he says.

“Our findings highlight the importance of filling the knowledge-gaps that currently limit our ability to understand and anticipate organismal responses to rapidly changing Earth system conditions.”

Published 24 June in the scientific journal Frontiers in Marine Science, the new study is titled: ‘Multi-Decadal Humpback Whale Migratory Route Fidelity Despite Oceanographic and Geomagnetic Change’.

Watch a video about the research: